CN211927125U - Temperature measurement circuit, temperature measurement and light measurement circuit, chip, module and electronic equipment - Google Patents

Abstract

The application relates to the field of biological characteristic parameter measurement, in particular to a temperature measurement circuit, a temperature measurement and light measurement circuit, a chip, a module and electronic equipment. The temperature signal is obtained by the first output voltage output by the non-load time difference amplifying circuit at the non-load input end of the differential amplifier, the second output voltage output by the differential amplifying circuit when the non-load input end of the differential amplifier is connected with the first end of the calibration resistor, and the third output voltage output by the time difference amplifying circuit when the non-load input end of the differential amplifier is connected with the first end of the thermistor, so that the accuracy of temperature measurement is improved.

Description

Temperature measurement circuit, temperature measurement and light measurement circuit, chip, module and electronic equipment

Technical Field

The application relates to the field of biological characteristic parameter measurement, in particular to a temperature measurement circuit, a temperature measurement and light measurement circuit, a chip, a module and electronic equipment.

Background

With the increasing demand for biometric parameters, conventional biometric parameter tests have been gradually eliminated, for example, a mercury thermometer is not widely used due to environmental pollution and low test efficiency, and an electronic thermometer is widely used. When a thermistor is used for testing temperature in the prior art, a measurement error is often large, for example, the measurement error may be large due to unstable power supply voltage or an offset voltage, so that the calculated resistance value of the thermistor is inaccurate.

SUMMERY OF THE UTILITY MODEL

To the great problem of temperature measurement error among the prior art, this application embodiment provides a temperature measurement circuit, a temperature measurement photometry circuit, chip, module and electronic equipment.

A first aspect of an embodiment of the present application provides a temperature measurement circuit, which is characterized in that: the circuit comprises a switch circuit, a differential amplification circuit and a conversion circuit; the thermistor and the calibration resistor are connected with a switch circuit, the switch circuit is connected with a differential amplification circuit, and the differential amplification circuit is connected with a conversion circuit; the differential amplifying circuit comprises a differential amplifier; the switch circuit comprises at least one switch unit so that the non-inverting input end of the differential amplifier is unloaded in a first time period, the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor in a second time period, and the non-inverting input end of the differential amplifier is connected with the first end of the thermistor in a third time period; when the non-load of the non-inverting input end of the differential amplifier is carried out, the differential amplifier circuit outputs a first output voltage; when the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor, the differential amplification circuit outputs a second output voltage; when the non-inverting input end of the differential amplifier is connected with the first end of the thermistor, the differential amplifying circuit outputs a third output voltage; the conversion circuit is used for outputting a temperature signal according to the first output voltage, the second output voltage and the third output voltage.

In a possible implementation form according to the first aspect, the conversion circuit comprises a first resistance value determiner and a first temperature determiner; the first resistance value determiner is connected with the first temperature determiner and used for outputting resistance value signals of the thermistor according to the first output voltage, the second output voltage and the third output voltage;

the first temperature determiner is used for converting the resistance value signal into a temperature signal.

In a possible implementation form according to the first aspect, the first resistance value determiner comprises a first subtractor, a first multiplier and a first divider;

the first subtractor is used for calculating a first difference value and a second difference value, wherein the first difference value is a difference value between the second output voltage and the first output voltage, and the second difference value is a difference value between the third output voltage and the first output voltage;

the first multiplier is used for calculating a first product, and the first product is the product of the first difference value and the resistance value of the calibration resistor;

the first divider is used for calculating to obtain a resistance signal, and the resistance signal is the first product divided by the second difference.

According to the first aspect, in a possible implementation manner, the conversion circuit further includes a first analog-to-digital converter, the first analog-to-digital converter is connected with the first resistance value determiner, the first analog-to-digital converter is configured to convert the resistance value signal into a digital resistance value signal, and the first temperature determiner is configured to convert the digital resistance value signal into a temperature signal.

In a possible implementation form according to the first aspect, the conversion circuit comprises a second analog-to-digital conversion circuit and a control circuit; the second analog-to-digital conversion circuit is connected with the control circuit;

the second analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the first output voltage, the second output voltage and the third output voltage to respectively obtain a first digital signal, a second digital signal and a third digital signal;

the control circuit is used for converting the first digital signal, the second digital signal and the third digital signal output by the analog-to-digital conversion circuit into temperature signals.

According to a first aspect, in one possible implementation, a control circuit includes: a second resistance determiner and a second temperature determiner;

the second resistance value determiner is connected with the second temperature determiner and is used for converting the first digital signal, the second digital signal and the third digital signal into a digital resistance value signal of the thermistor;

the second temperature determiner is for converting the digital resistance signal to a temperature signal.

In one possible implementation form according to the first aspect, the second resistance value determiner includes a second subtractor, a second multiplier, and a second divider;

the second subtractor is used for calculating a third difference value and the fourth difference value, wherein the third difference value is the difference value between the second digital signal and the first digital signal, and the fourth difference value is the difference value between the third digital signal and the first digital signal;

the second multiplier is used for calculating a second product, and the second product is the product of the third difference value and the resistance value of the calibration resistor;

the second divider is used for calculating to obtain a digital resistance signal, and the digital resistance signal is the second product divided by the fourth difference.

According to the first aspect, in one possible implementation, the converting circuit outputting the temperature signal according to the first output voltage, the second output voltage, and the third output voltage includes:

determining the resistance value of the thermistor according to the first output voltage, the second output voltage and the third output voltage;

and outputting a temperature signal according to the resistance value of the thermistor.

According to the first aspect, in one possible implementation, determining the resistance value of the thermistor according to the first output voltage, the second output voltage, and the third output voltage includes:

the resistance value of the thermistor is equal to the product of the first difference value and the calibration resistor divided by the second difference value; the first difference is a difference between the second output voltage and the first output voltage, and the second difference is a difference between the third output voltage and the first output voltage.

According to the first aspect, in one possible implementation, the inverting input of the differential amplifier is connected to a first voltage; the second end of the thermistor is connected with a second voltage; the second end of the calibration resistor is connected with a second voltage; the second voltage is greater than or less than the first voltage.

According to the first aspect, in a possible implementation manner, the differential amplifier circuit further includes a feedback resistor, two ends of the feedback resistor are respectively connected to the non-inverting input terminal and the inverting output terminal of the differential amplifier, a resistance value of the calibration resistor is greater than twice a resistance value of the feedback resistor multiplied by a first preset absolute value, and the first preset absolute value is an absolute value of a quotient obtained by dividing a difference value between the first voltage and the second voltage by the power supply voltage.

According to the first aspect, in one possible implementation manner, when the non-load is applied to the non-inverting input terminal of the differential amplifier, the gain of the differential amplification circuit is 0; when the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor, the gain of the differential amplifier circuit is 2 times of the resistance value of the feedback resistor divided by the resistance value of the calibration resistor; when the non-inverting input end of the differential amplifier is connected with the first end of the thermistor, the gain of the differential amplifier circuit is 2 times of the resistance value of the feedback resistor divided by the resistance value of the thermistor.

According to the first aspect, in one possible implementation, the second voltage is a ground voltage; the first voltage is a common mode voltage; the resistance value of the feedback resistor is smaller than that of the calibration resistor.

According to the first aspect, in one possible implementation, the switching circuit includes a first switching unit, a second switching unit;

in a first time period, the first switch unit and the second switch unit are both in an off state, and when the first switch unit and the second switch unit are both in the off state, the non-load of the non-inverting input end of the differential amplifier is enabled, so that the differential amplifier circuit outputs a first output voltage;

in a second time period, the first switch unit is in a closed state, and when the first switch unit is in the closed state, the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor, so that the differential amplification circuit outputs a second output voltage;

in a third time period, the second switch unit is in a closed state; when the second switch unit is in a closed state, the non-inverting input end of the differential amplifier is connected with the first end of the thermistor, so that the differential amplification circuit outputs a third output voltage.

According to the first aspect, in one possible implementation manner, the switch circuit is a one-out-of-three switch circuit, and the one-out-of-three switch circuit is used for switching the connection state of the non-inverting input terminal of the differential amplifier in the first time period, the second time period and the third time period respectively, so that the non-inverting input terminal of the differential amplifier is unloaded or connected with the first end of the calibration resistor or connected with the first end of the thermistor.

According to the first aspect, in one possible implementation, the first time period, the second time period, and the third time period are consecutive in time; the sum of the first time period, the second time period and the third time period is less than or equal to a first preset time length, and the third time period is greater than or equal to a second preset time length.

In a possible implementation manner, according to the first aspect, the first preset time period is 30 microseconds; the second preset time is 1 microsecond.

In a possible implementation manner, the time lengths of the first time period, the second time period and the third time period are all less than or equal to 10 microseconds.

According to the first aspect, in one possible implementation manner, the first time period is earlier than the second time period, and the second time period is earlier than the third time period; or

The second time period is earlier than the third time period, which is earlier than the first time period.

In a possible implementation form according to the first aspect, the feedback resistor and the calibration resistor are non-sensitive resistors.

According to the first aspect, in a possible implementation, the calibration resistor is a precision resistor, the temperature drift of the calibration resistor is less than or equal to 10 ppm/DEG C, and the precision of the calibration resistor is less than or equal to one thousandth.

In a possible implementation form according to the first aspect, the differential amplifying circuit is a differential programmable gain amplifying circuit.

A second aspect of an embodiment of the present application provides a temperature measurement and light measurement circuit, including any one of the temperature measurement circuits in the first aspect; the switching circuit includes at least one switching unit to connect the non-inverting input terminal of the differential amplifier to the front stage of the photodiode for a fourth time period; when the non-inverting input end of the differential amplifier is connected with the front stage of the photodiode, the differential amplifier circuit outputs a fourth output voltage; the conversion circuit outputs a light intensity signal according to the fourth output voltage.

According to the second aspect, in one possible implementation manner, the back stage of the photodiode is connected to a second voltage, and the second voltage is a ground voltage.

According to the second aspect, in one possible implementation manner, the converting circuit outputting the light intensity signal according to the fourth output voltage includes:

determining the current passing through the photodiode according to the fourth output voltage;

and outputting a light intensity signal according to the current passing through the photodiode.

According to the second aspect, in one possible implementation, the determining the magnitude of the current through the photodiode according to the fourth output voltage includes:

the current passing through the photodiode is the fourth output voltage divided by twice the resistance of the feedback resistor.

According to a second aspect, in one possible implementation, the conversion circuit comprises a current determiner and a light intensity determiner; the current determiner is connected with the light intensity determiner;

the current determiner is used for outputting a current signal passing through the photodiode according to the fourth output voltage;

the light intensity determiner is used for outputting a light intensity signal according to the current signal passing through the photodiode.

According to the second aspect, in one possible implementation, the current determiner includes a third divider for calculating a current signal, which is the fourth output voltage divided by twice the resistance value of the feedback resistance.

A third aspect of embodiments of the present application provides a chip, which includes any one of the thermometry circuits in the first aspect or includes any one of the thermometry and photometry circuits in the second aspect.

A fourth aspect of embodiments of the present application provides a module comprising: a substrate, a thermistor, a calibration resistor and a chip in the third aspect, the chip being connected to the substrate.

A fifth aspect of embodiments of the present application provides an electronic device, comprising: a housing and the chip of the third aspect, the chip being disposed within the housing.

Compared with the prior art, the beneficial effects of the embodiment of the application lie in that: the embodiment of the application provides a temperature measurement circuit, temperature measurement and light measurement circuit, chip, module and electronic equipment, when the first output voltage of the non-load time difference of the non-inverting input end through differential amplifier, the first end of calibration resistor is connected to the non-inverting input end of differential amplifier the third output voltage of the first end time difference of the output of thermistor is connected to the non-inverting input end of second output voltage, differential amplifier of differential amplifier output of differential amplifier circuit and obtains temperature signal, has improved the inaccurate problem of temperature measurement among the prior art.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a schematic diagram of a temperature measurement circuit according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 3A is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 3B is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 3C is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 3D is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 3E is a schematic diagram of a second resistance determiner according to an embodiment of the disclosure;

FIG. 3F is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

fig. 4 is a flowchart of a temperature measurement method corresponding to the temperature measurement circuit according to the embodiment of the present disclosure;

FIG. 5A is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

FIG. 5B is a schematic diagram of a first resistance determiner according to an embodiment of the disclosure;

FIG. 5C is a schematic diagram of another temperature measuring circuit according to an embodiment of the present disclosure;

fig. 5D is a flowchart of another temperature measuring method corresponding to the temperature measuring circuit provided in the embodiment of the present application;

FIG. 6 is a flowchart of another temperature measurement method corresponding to the temperature measurement circuit according to the embodiment of the present disclosure;

fig. 7A is a schematic diagram of a temperature measurement and light measurement circuit according to an embodiment of the present disclosure;

fig. 7B is a schematic diagram of another temperature measurement and light measurement circuit provided in the embodiment of the present application;

fig. 8 is a flowchart of a photometry method corresponding to the temperature and light measurement circuit according to the embodiment of the present application;

fig. 9 is a flowchart of another light measuring method corresponding to the temperature measurement light measuring circuit according to the embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, some embodiments of the present application will be described in detail by way of example with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that in the examples, numerous technical details are set forth in order to provide a better understanding of the present application. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.

Referring to the temperature measuring circuit shown in fig. 1, specifically, it may be referred to as a resistance voltage division temperature measuring circuit, the sensitive resistor 100 is used for measuring temperature, specifically, the sensitive resistor 100 may be a thermistor, the thermistor is denoted by RT, the amplifying circuit 101 includes an Amplifier AMP (Amplifier), an inverting input terminal of the Amplifier is connected to an output terminal of the Amplifier, the non-sensitive resistor 102 is denoted by R, the non-sensitive resistor may be a resistor with a fixed resistance value or an adjustable resistance value, it can be understood that the non-sensitive resistor refers to a resistor of which the resistance value hardly changes with environmental factors, the first end of the thermistor and the first end of the non-sensitive resistor are both connected with the non-inverting input end of the amplifier, the second end of the non-sensitive resistor is connected with a supply voltage VCC, the VCC may also be referred to as a supply voltage, and the second end of the thermistor is connected with a ground voltage GND. The Analog-to-Digital Converter circuit 103 is represented by an ADC (Analog-to-Digital Converter), and the controller circuit 104 is represented by an MCU (micro controller Unit). The amplifier AMP may be an operational amplifier, for example, a unity gain amplifier, the power supply voltage VCC is divided by the non-sensitive resistor 102 and the thermistor 100, and then is driven by the unity gain amplifier, the analog-to-digital converter ADC converts the output voltage Vout of the operational amplifier into a digital signal, and the controller circuit 104 performs digital processing on the digital signal to obtain a temperature signal. From fig. 1, the resistance value of the thermistor can be expressed as: RT = Vout × R/(VCC-Vout). The circuit scheme shown in fig. 1 is simple, but if the power supply voltage of the temperature measuring circuit is unstable, since the value of RT is directly related to VCC, the temperature measurement is likely to be inaccurate due to the unstable power supply voltage; in addition, because the offset voltage exists in the amplifying circuit, the resistance value of the thermistor can be calculated inaccurately, so that the temperature measurement is inaccurate; in addition, due to the environmental changes, such as temperature changes, the finally calculated thermistor value may not be accurate due to the temperature drift of the power supply voltage VCC, the resistor R, or the offset voltage of the operational amplifier.

Based on the disclosure of the above embodiments, in the present embodiment, the temperature measuring circuit shown in fig. 2 can be referred to as a constant current source driving temperature measuring circuit, the thermistor 200 is represented by RT, and the calibration resistor 205 is represented by Rc, wherein the calibration resistor is a non-sensitive resistor. VREF may be a voltage provided by a voltage reference source, VREF may be referred to as a voltage reference source voltage, the current regulation resistor 202 is denoted by R, the current regulation resistor 202 is a non-sensitive resistor, the current regulation resistor is used to set a current Iref of the current source circuit 206, the current source circuit may also be referred to as a constant current source circuit, the current source circuit 206 includes an amplifier 207 and a switch circuit 208, the specific switch circuit may include an N-channel enhancement type field effect transistor, and the current provided by the constant current source is Iref = VREF/R; when VREF and the current regulating resistor R are constant, the current Iref is constant. The thermometry circuit of fig. 2 includes a one-out-of-three switch, which may be an analog switch, for example. The one-out-of-three switch comprises contacts 2, 3 and 4, offset voltage Vos of the temperature measurement circuit can be respectively measured through the connection or disconnection of the one-out-of-three switch, the influence of Vos on temperature measurement can be improved through offsetting Vos subsequently, and in addition, the influence of unstable power supply voltage can be avoided through measuring the output voltage of the amplifying circuit 201 under different gains Gain, so that the precision of calculating the thermistor 200 is improved. The amplifying circuit 201 in this embodiment may be a differential amplifying circuit including a differential amplifier.

The circuit shown in fig. 2 adopts a time-sharing sampling mechanism, in this embodiment, sampling may refer to collecting output voltage of the differential amplifier circuit, and specifically, sampling may be performed in three time periods:

in a first time period, the analog switch is switched to the contact 4, that is, at a position of a short circuit where the non-inverting input terminal and the inverting input terminal of the differential amplifier are connected to each other, the amplifying circuit 201 includes an INA (instrumentation amplifier), at this time, the voltages of the non-inverting input terminal and the inverting input terminal of the amplifying circuit 201 are equal, the differential input voltage is 0, and the output of the amplifying circuit 201 is the offset voltage Vos of the circuit; it should be understood that, in this embodiment, for the amplifier, the non-inverting input terminal may also be referred to as a non-inverting input terminal, and the inverting input terminal may also be referred to as a inverting input terminal.

In the second time period, the analog switch is switched to the contact point 2, that is, the analog switch is switched to a position where the non-inverting input terminal and the inverting input terminal of the amplifier are connected to both ends of the calibration resistor 205, at this time, the input voltage between the non-inverting input terminal and the inverting input terminal of the amplifier is Iref Rc, and the output voltage amplified by the differential amplifier circuit 201 is Vc = Iref Rc Gain + Vos.

In the third time period, the analog switch is switched to the contact 3, that is, the analog switch is switched to a position where the non-inverting input terminal and the inverting input terminal of the amplifier are connected to both ends of the thermistor 200, the input voltage of the non-inverting input terminal and the inverting input terminal of the amplifying circuit 201 is Iref RT, and the amplified output voltage of the input voltage of the amplifier is VT = Iref RT Gain + Vos.

Vos, Vc, and VT obtained from the above test of the three periods of time may result in Iref × Gain = (Vc-Vos)/Rc = (VT-Vos)/RT. The size of the thermistor 200 can be determined as RT = (VT-Vos) × Rc/(Vc-Vos). The thermistor size obtained by the constant current source driving temperature measuring circuit shown in fig. 2 is only related to the output of the amplifier and the resistance value of the calibration resistor, and is not related to the power supply voltage VCC, so that even if the power supply voltage VCC is unstable, the accuracy of temperature measurement will not be greatly reduced due to the unstable VCC. Compared with the scheme of fig. 1, the problem of measurement accuracy caused by unstable power supply voltage can be effectively avoided, and in addition, the circuit shown in fig. 2 has a constant current source circuit, so that the cost and the volume of the circuit are large. It should be noted that the sequence of the three time periods does not necessarily need to be the sequence of the first time period, the second time period, and the third time period, and may also be other sequences, for example, the analog switch may contact the contact 2 first, then contact the contact 3, and finally contact the contact 4; or contact 3, contact 4 and contact 2; the present embodiment does not limit the order of turning on the analog switch. In addition, the first time period, the second time period and the third time period can be set to be shorter, for example, in a short time of a microsecond level, because the temperature generally does not change instantaneously, parameters in the circuit also do not change basically, for example, the resistance value of the calibration resistor and the offset voltage Vos do not change basically, and therefore the thermistor obtained through testing is more accurate.

Based on the disclosure of the above embodiments, the present embodiment provides a temperature measurement circuit, which uses fewer components, can effectively reduce the cost and volume of the circuit, and can improve the problem of inaccurate temperature measurement.

The thermometric circuit shown in fig. 3A includes a switching circuit 310, a Differential Amplifier (DA) circuit 301, and a conversion circuit 308, in which the switching circuit 310 is connected to the Differential Amplifier circuit 301, and the Differential Amplifier circuit 301 is connected to the conversion circuit 308. In the present embodiment, the differential Amplifier circuit 301 includes a PGA (differential Programmable Gain Amplifier) for example. Thermistor 300 is represented by RT, calibration resistor 305 by Rc, feedback resistor 306 by Rf, and feedback resistor 306 and calibration resistor 305 are non-sensitive resistors. The differential amplifying circuit 301 includes a differential amplifier 307. The switch circuit 310 includes at least one switch unit, and the switch circuit 310 can set different gains Gain of the temperature measuring circuit to obtain the resistance value of the thermistor 300. When the contact of the switching unit is connected to the contact 3, the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the thermistor 300; when the contact of the switching unit is connected to the contact 2, the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the calibration resistor 305; when the contact of the switching unit is connected to the contact 1, the non-inverting input terminal of the differential amplifier 307 can be made idle. Specifically, the switch unit makes the non-load of the non-inverting input end of the differential amplifier in a first time period, and at the time, the differential amplification circuit outputs a first output voltage; the switch unit enables the non-inverting input end of the differential amplifier to be connected with the first end of the calibration resistor in a second time period, and at the moment, the differential amplifier circuit outputs a second output voltage; the switch unit enables the non-inverting input end of the differential amplifier to be connected with the first end of the thermistor in a third time period, at the moment, the differential amplification circuit outputs a third output voltage, and the conversion circuit is used for outputting a temperature signal according to the first output voltage, the second output voltage and the third output voltage. Referring to fig. 4, the corresponding temperature measuring method for the temperature measuring circuit includes the following steps:

s401: in a first time period, the non-load of the non-inverting input end of the differential amplifier is carried out;

in step S401, when the non-load is applied to the non-inverting input terminal of the differential amplifier 307, the output voltage of the differential amplifier circuit 301 is the first output voltage, and at this time, the first output voltage may also be referred to as an offset voltage Vos, and it can be understood that, in the first period, the non-load is applied to the non-inverting input terminal of the differential amplifier, and the voltage of the non-inverting input terminal of the differential amplifier is equal to the voltage of the inverting input terminal of the differential amplifier, so that the differential input voltage of the differential amplifier in the first period is 0V, and ideally, the output voltage of the differential amplifier circuit is also 0V, but in an actual circuit, due to the presence of the offset voltage, the output of the differential amplifier circuit in the first period may not be 0V. Therefore, the offset voltage Vos of the circuit can be tested, so that the accuracy of temperature measurement can be improved according to the offset voltage. It should be understood that the offset voltage of this embodiment may also be referred to as an input offset voltage, which refers to the difference between the dc voltages applied to the two input terminals in the differential amplifier or the differential input operational amplifier in order to obtain a constant zero voltage output at the output terminal.

S402: in a second time period, the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor;

in step S402, when the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the calibration resistor 305, the output voltage of the differential amplifier circuit 301 is the second output voltage, which may be denoted as Vc for convenience of description, the second terminal of the calibration resistor 305 is connected to the second voltage VSS, and the inverting input terminal of the differential amplifier 307 is connected to the first voltage VDD, so that the differential input voltage of the differential amplifier 307 is (VSS-VDD), and in the second time period, the Gain of the differential amplifier circuit 301 is 2Rf/Rc, and thus, the second output voltage Vc = (VSS-VDD) × 2Rf/Rc + Vos can be obtained; wherein, Rf is a feedback resistance between the non-inverting input terminal and the inverting output terminal of the amplifier. It should be noted that, at both ends of the differential amplifier, a feedback resistor Rf and a feedback capacitor Cf may be arranged in parallel, and the following description will be given by taking an example in which the feedback resistor Rf is arranged between the non-inverting input terminal and the inverting output terminal.

S403: in a third time period, the non-inverting input end of the differential amplifier is connected with the first end of the thermistor;

in step S403, when the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the thermistor RT, the output voltage of the differential amplifier circuit 301 is the third output voltage, for convenience of description, the third output voltage is denoted as VT, the second terminal of the calibration resistor is connected to the second voltage VSS, and the inverting input terminal of the differential amplifier 307 is connected to the first voltage VDD, so that the differential input voltage of the differential amplifier 307 in the third time period is (VSS-VDD), and the Gain of the differential amplifier circuit 301 is 2Rf/RT, and therefore, the third output voltage VT = (VSS-VDD) × 2Rf/RT + Vos can be obtained.

Fig. 4 only illustrates the sequence of steps S401, S402, and S403, but does not limit the sequence of steps S401, S402, and S403, that is, does not limit the sequence of the first time period, the second time period, and the third time period. Specifically, the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the thermistor 300 to obtain the third output voltage VT, the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the calibration resistor 305 to obtain the second output voltage Vc, and the non-inverting input terminal of the differential amplifier may be unloaded to obtain the first output voltage Vos (i.e., the execution sequence is S403-S402-S401); or the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the thermistor 300 to obtain the third output voltage VT, the non-load of the non-inverting input terminal of the differential amplifier 307 may be further performed to obtain the first output voltage Vos, and finally the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the calibration resistor 305 to obtain the second output voltage Vc (i.e., the execution sequence is S403-S401-S402); or the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the calibration resistor 305 to obtain the second output voltage Vc, the non-inverting input terminal of the differential amplifier 307 is unloaded to obtain the first output voltage Vos, and the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the thermistor 300 to obtain the third output voltage VT (i.e., the execution sequence is S402-S401-S403); or the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the calibration resistor 305 to obtain the second output voltage Vc, the non-inverting input terminal of the differential amplifier 307 may be connected to the first terminal of the thermistor 300 to obtain the third output voltage VT, and the non-inverting input terminal of the differential amplifier 307 may be unloaded to obtain the first output voltage Vos (i.e., the execution sequence is S402-S403-S401); alternatively, the non-load of the non-inverting input terminal of the differential amplifier 307 is performed to obtain the first output voltage Vos, the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the thermistor 300 to obtain the third output voltage VT, and the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the calibration resistor 305 to obtain the second output voltage Vc (i.e., the execution sequence is: S401-S403-S402).

After the first output voltage Vos, the second output voltage Vc, and the third output voltage VT are obtained through the test, step S404 may be executed;

s404: the conversion circuit outputs a temperature signal according to the first output voltage, the second output voltage and the third output voltage.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 5A, the converting circuit 58 may include a first resistance value determiner 53 and a first temperature determiner 54, where the first resistance value determiner 53 is connected to the first temperature determiner 54. The first resistance determiner is used for outputting resistance signals of the thermistor according to the first output voltage, the second output voltage and the third output voltage, and the first temperature determiner is used for converting the resistance signals into temperature signals. In this embodiment, the switch circuit 51, the differential amplifier circuit 52, the differential amplifier 57, the feedback resistor 56, the conversion circuit 58, the thermistor 50, and the calibration resistor 55 are the same as or similar to those in the previous embodiments, and are not described herein again.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 5B, the first resistance value determiner 53 may include a first subtractor 531, a first multiplier 532 and a first divider 533. The first subtractor is used for calculating a first difference value and a second difference value, wherein the first difference value is the difference value between the second output voltage Vc and the first output voltage Vos, and the second difference value is the difference value between the third output voltage VT and the first output voltage Vos; the first multiplier is used for calculating a first product, and the first product is the product of the first difference value (Vc-Vos) and the resistance value of the calibration resistor Rc; the first divider is used for calculating a resistance signal, and the resistance signal is a first product (Vc-Vos) × Rc divided by a second difference (VT-Vos). Fig. 5B shows only the structure of the first resistance value determiner 53, and it is understood that the first subtractor is connected to the differential amplifying circuit 52 and the first divider is connected to the first temperature determiner. Specifically, the first temperature determiner may include an MCU, for example, the MCU may convert the resistance value signal into a temperature signal according to a corresponding relationship between the resistance value of the thermistor RT and the temperature. In addition, the thermometry circuit may also include one or more registers to store the calculated parameters.

Based on the disclosure of the above embodiment, in this embodiment, referring to fig. 5C, the conversion circuit further includes a first analog-to-digital converter 59, the first analog-to-digital converter 59 is connected to the first resistance value determiner 53, the first analog-to-digital converter is configured to convert the resistance value signal into a digital resistance value signal, the digital resistance value signal can be understood as an expression form of a digital signal of the resistance value of the thermistor, the first analog-to-digital converter is further connected to the first temperature determiner 54, and the first temperature determiner 54 is configured to convert the digital resistance value signal into a temperature signal. Specifically, the first analog-to-digital converter may be connected to the first divider, and is configured to convert the resistance signal obtained by the divider into a digital resistance signal, where the digital resistance signal may be understood as a resistance value of the digital thermistor. Based on the disclosure of the above embodiments, in this embodiment, referring to fig. 5D, the step of outputting the temperature signal by the conversion circuit according to the first output voltage, the second output voltage and the third output voltage may include the following steps:

s504: determining the resistance value of the thermistor according to the first output voltage, the second output voltage and the third output voltage;

s505: and outputting a temperature signal according to the resistance value of the thermistor.

Steps S501 to S503 are the same as or similar to steps S401 to S403 in the foregoing embodiment, and are not described herein again. In the foregoing steps S401 to S403, the first output voltage Vos has been obtained, and the magnitude relationship between the second output voltage Vc and the first voltage, the second voltage, the resistance value of the feedback resistor, the resistance value of the calibration resistor, and the first output voltage Vos has been clarified, and the magnitude relationship between the third output voltage VT and the first voltage, the second voltage, the resistance value of the feedback resistor, the resistance value of the thermistor, and the first output voltage Vos has been clarified, whereby the resistance value of the thermistor can be determined. Specifically, the resistance value of the thermistor RT may be determined according to the first output voltage Vos, the second output voltage Vc, the third output voltage VT, and the resistance value of the calibration resistor Rc. After the resistance value of the thermistor RT is determined, the temperature can be determined according to the resistance value of the thermistor RT, and then a temperature signal is output, specifically, the temperature measuring circuit can further include an output circuit, the control circuit can be connected with the output circuit, the output circuit can be used for displaying the temperature, for example, the output circuit can include a display screen, and the output form of the temperature signal can be displayed on the display screen, for example, or output in the form of voice. It is understood that the resistance value of the thermistor RT varies with the temperature, and the resistance value of the thermistor RT has a correspondence with the temperature, and thus, after the resistance value of the thermistor RT is determined, the temperature is also determined. In addition, the user can select a proper thermistor according to the temperature measurement range and select the temperature drift and the precision of the thermistor.

Based on the disclosure of the above embodiment, in this embodiment, the temperature measuring circuit may include a thermistor and a calibration resistor, that is, the thermistor and the calibration resistor may be on one chip with the switch circuit, the differential amplifier circuit and the conversion circuit, and in addition, the temperature measuring circuit may not include the thermistor and the calibration resistor, that is, the thermistor and the calibration resistor may be connected to the temperature measuring circuit as an external device, so that a user may select the thermistor and the calibration resistor according to a requirement, and select the thermistor and the calibration resistor suitable for the requirement to be connected to the temperature measuring circuit, so as to meet different requirements.

Based on the disclosure of the above embodiments, in the present embodiment, determining the resistance value of the thermistor RT according to the first output voltage Vos, the second output voltage Vc, and the third output voltage VT includes that the resistance value of the thermistor RT is equal to the product of the first difference and the calibration resistance Rc divided by the second difference; the first difference is a difference between the second output voltage Vc and the first output voltage Vos, and the second difference is a difference between the third output voltage VT and the first output voltage Vos. Specifically, since Vc = (VSS-VDD) × 2Rf/Rc + Vos, VT = (VSS-VDD) × 2Rf/RT + Vos, (VSS-VDD) × 2Rf = (Vc-Vos) × Rc = (VT-Vos) × RT, RT = (Vc-Vos) × Rc/(VT-Vos) can be obtained, and the magnitude of the resistance value of the thermistor RT is related to the first output voltage Vos, the second output voltage Vc, the third output voltage VT, and the resistance value of the calibration resistor Rc.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 3A, an inverting input terminal of the differential amplifier 307 is connected to the first voltage VDD; the second end of the thermistor RT is connected with a second voltage VSS; the second end of the calibration resistor Rc is connected with a second voltage VSS; the second voltage VSS is not equal to the first voltage VDD; the first voltage VDD may be greater than the ground voltage and less than the power supply voltage. The second voltage VSS may be greater than or equal to the ground voltage and less than the power supply voltage. In this embodiment, if the first voltage VDD is equal to the second voltage VSS, the differential input voltage of the differential amplifier 307 is 0, and the output voltages of the differential amplifier 307 in the first time period, the second time period and the third time period are all the offset voltage Vos, so that, in order to accurately test the temperature, the first voltage VDD is not equal to the second voltage VSS, that is, the first voltage is greater than or less than the second voltage.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 3A, the differential amplifying circuit 301 further includes a feedback resistor 306, that is, the amplifying circuit 301 includes an amplifier 307 and the feedback resistor 306. Two ends of the feedback resistor 306 are respectively connected with the non-inverting input end and the inverting output end of the differential amplifier 307; in this embodiment, the inverting output terminal may also be referred to as a negative phase output terminal, and the non-inverting output terminal may also be referred to as a non-inverting output terminal. In order to avoid saturation of the amplifier as much as possible, in the first period, the second period, and the third period, the output of the differential amplifying circuit 301 is less than the power supply voltage VCC, for a second time period, Vc = [ (VSS-VDD) × 2Rf/Rc + Vos ] < VCC, since VSS-VDD may be positive or negative, and correspondingly, the second output voltage Vc may also be positive or negative, since the first output voltage Vos is generally small, if the first output voltage Vos is ignored, Rc > 2Rf | (VSS-VDD)/VCC |, the resistance value Rc of the calibration resistor is larger than the resistance value of the feedback resistor multiplied by a first preset absolute value, and the first preset absolute value | (VSS-VDD)/VCC | is the absolute value of the quotient of the difference value of the first voltage VSS and the second voltage VDD divided by the power supply voltage VCC; in addition, assuming that the influence of Vos is not ignored, Rc > 2Rf | (VSS-VDD)/(VCC-Vos) |, i.e. the resistance Rc of the calibration resistor is greater than twice the resistance of the feedback resistor multiplied by a second predetermined absolute value, | (VSS-VDD)/(VCC-Vos) |, which is the absolute value of the quotient of the difference between the first voltage VSS and the second voltage VDD divided by the difference between the power supply voltage VCC and the first output voltage Vos.

Based on the disclosure of the above embodiment, in this embodiment, when the non-load is applied to the non-load input terminal of the differential amplifier 307 in the first time period, the gain of the differential amplifier circuit is 0; in the second time period, when the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the calibration resistor, the Gain of the differential amplifier circuit is 2 times of the resistance value of the feedback resistor divided by the resistance value of the calibration resistor, that is, Gain =2 × Rf/Rc; in the third time period, when the non-inverting input terminal of the differential amplifier 307 is connected to the first terminal of the thermistor, the Gain of the differential amplifier circuit is 2 times the resistance value of the feedback resistor divided by the resistance value of the thermistor, that is, Gain =2 × Rf/RT.

Based on the disclosure of the above embodiments, referring to fig. 3B, in the embodiment, the first voltage VDD may be a common mode voltage Vcm, Vcm = VCC/2, and since a voltage source of the common mode voltage is generally set in the circuit, when the first voltage is the common mode voltage, it is not necessary to additionally set a VDD generation circuit, which can reduce the cost and the circuit volume. Further, in order to avoid saturation of the amplifier as much as possible so that the amplifier can ensure normal operation, 2 × Rf/RT < VCC/Vcm =2, and in addition, 2 × Rf/Rc < VCC/Vcm =2, that is, the resistance value of the calibration resistor Rc is greater than that of the feedback resistor Rf, or the resistance value of the feedback resistor Rf is smaller than that of the calibration resistor Rc. For example, the feedback resistance Rf =10k Ω and the calibration resistance Rc =30k ohms. At least making the resistance value of the feedback resistor Rf smaller than that of the calibration resistor Rc can improve the stability of the circuit to make the measurement result more accurate. In addition, since the ground voltage is generally set in the circuit, the second voltage can be the ground voltage, so that a second voltage generating circuit is not needed to be additionally arranged, the cost can be reduced, and the circuit size can also be reduced.

Based on the disclosure of the above embodiments, in this embodiment, the switch circuit may be a one-out-of-three switch circuit, that is, the switch unit is a one-out-of-three switch circuit for switching the connection state of the non-inverting input terminal of the differential amplifier in the first time period, the second time period and the third time period, specifically, referring to fig. 3A, the one-out-of-three switch circuit may include contacts 1, 2 and 3. The output under the offset voltage Vos and the different gains Gain of the circuit can be respectively measured through the connection state of the contact and the contact of the three-out-of-one switching circuit, so that the influence of unstable power supply voltage on the accuracy of the measurement result is avoided, and the precision of calculating the thermistor is improved. The one-out-of-three switch circuit may be an analog switch, the temperature measuring circuit adopts a time-sharing sampling mechanism, specifically, the first voltage is a common-mode voltage Vcm, the second voltage is GND for example, referring to fig. 6, the temperature measuring method corresponding to the temperature measuring circuit may include the following steps:

s601: in the first time period, the one-out-of-three switching circuit is switched to a position where the non-inverting input terminal of the differential amplifier is disconnected. That is, the contact of the one-out-of-three switch contacts the contact 1, at this time, the non-load of the non-inverting input end of the differential amplifier 301, and the output Vout of the differential amplifier circuit is the offset voltage Vos of the amplifier circuit;

s602: in the second period, the one-out-of-three switch circuit is switched to a position such that the non-inverting input terminal of the differential amplifier is connected to the calibration resistance Rc. Specifically, the non-inverting input terminal of the differential amplifier is connected to the first end of the calibration resistor Rc, i.e., the contact point 2 of the one-out-of-three switch, the non-inverting input terminal of the differential amplifier is connected to the first end of the calibration resistor Rc, the Gain of the differential amplification circuit 301 is determined by the feedback resistor 306 and the calibration resistor 305, specifically, Gain of the differential amplification circuit is 2 × Rf/Rc, and therefore, the output voltage of the differential amplification circuit is Vc = Vcm × 2Rf/Rc + Vos;

s603: in a third time period, the one-out-of-three switch circuit is switched to a position such that the non-inverting input terminal of the differential amplifier is connected to the thermistor. Specifically, the non-inverting input terminal of the differential amplifier is connected to the first terminal of the thermistor RT, that is, the contact 3 of the one-out-of-three switch, the Gain of the differential amplifier circuit 301 is determined by the feedback resistor 306 and the thermistor 300, specifically, Gain of the differential amplifier circuit is 2 × Rf/RT, and the output voltage after passing through the differential amplifier circuit is VT = Vcm × 2Rf/RT + Vos.

Therefore, from the above two formulas, Vcm = (Vc-Vos) × Rc = (VT-Vos) × RT, that is, the size of the thermistor RT can be obtained as RT = (Vc-Vos) × Rc/(VT-Vos). The size of the thermistor RT obtained by the temperature measurement circuit shown in fig. 3A and 3B is only related to the output of the differential amplifier circuit and the resistance value of the calibration resistor, and compared with the scheme shown in fig. 1, the problem of low temperature measurement accuracy caused by unstable power supply voltage can be effectively avoided.

Based on the disclosure of the above embodiments, in the present embodiment, the switch circuit 310 may include a first switch unit and a second switch unit, please refer to fig. 3C, when the first switch unit 10 and the second switch unit 20 are both in the off state in the first time period, the non-load of the non-inverting input terminal of the differential amplifier is no-load, so that the differential amplifier circuit intermittently outputs the first output voltage Vos in the first time period;

in a second time period, the first switch unit 10 is in a closed state, and the non-inverting input terminal of the differential amplifier is connected to the first terminal of the calibration resistor, so that the differential amplifier circuit outputs a second output voltage Vc in the second time period; when the first switching unit 10 is in the closed state, the second switching unit 20 is in the open state.

In a third time period, the second switching unit 20 is in a closed state, and the non-inverting input terminal of the differential amplifier is connected to the first terminal of the thermistor, so that the differential amplifying circuit outputs a third output voltage VT in the third time period; when the second switching unit 20 is in the closed state, the first switching unit 10 is in the open state.

Based on the disclosure of the above embodiments, in the present embodiment, please refer to fig. 3B or 3C, the conversion circuit includes a second analog-to-digital conversion circuit 303 and a control circuit 304.

The analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the first output voltage, the second output voltage and the third output voltage of the differential amplification circuit to respectively obtain a first digital signal, a second digital signal and a third digital signal; it is understood that the first digital signal is a representation of the first output voltage in the form of a digital signal, the second digital signal is a representation of the second output voltage in the form of a digital signal, and the third digital signal is a representation of the third output voltage in the form of a digital signal.

The control circuit 304 is used for converting the first digital signal, the second digital signal and the third digital signal output by the analog-to-digital conversion circuit into a temperature signal.

Specifically, in this embodiment, the analog-to-digital conversion circuit performs analog-to-digital conversion on the first output voltage, the second output voltage, and the third output voltage of the differential amplification circuit, the first output voltage, the second output voltage, and the third output voltage after analog-to-digital conversion are digital signals, and the control circuit processes the digital signals to obtain temperature signals, in a processing manner, referring to the method for obtaining the thermistor resistance value mentioned in the above embodiment, and then obtains the temperature signals according to the corresponding relationship between the thermistor resistance value and the temperature.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 3D, the control circuit 304 includes a second resistance value determiner 341 and a second temperature determiner 342, the second resistance value determiner is connected to the second temperature determiner, and the second resistance value determiner is configured to convert the first digital signal, the second digital signal, and the third digital signal into digital resistance value signals; the second resistance value determiner is connected with the second analog-to-digital converter, and the second temperature determiner is used for converting the digital resistance value signal into a temperature signal.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 3E, the second resistance value determiner includes a second subtractor 343, a second multiplier 344, and a second divider 345;

the second subtracter is used for calculating a third difference value and a fourth difference value, wherein the third difference value is the difference value (Vc-Vos) between the second digital signal and the first digital signal, and the fourth difference value is the difference value (VT-Vos) between the third digital signal and the first digital signal;

the second multiplier is used for calculating a second product, and the second product is the product (Vc-Vos) Rc of the third difference value and the resistance value of the calibration resistor;

the second divider is used for calculating to obtain a digital resistance signal, and the digital resistance signal is the second product divided by the fourth difference (Vc-Vos) × Rc/(VT-Vos).

Based on the disclosure of the above embodiments, in this embodiment, the first time period, the second time period and the third time period are consecutive in time, that is, three time periods are immediately adjacent to one another, for example, the first time period is immediately adjacent to the second time period, a time interval between the first time period and the second time period is 0, and the third time period may be immediately adjacent to the first time period, or may be immediately adjacent to the second time period, a time interval between the third time period and the first time period is 0, or a time interval between the third time period and the second time period is 0, so as to implement that the test is completed in consecutive time, so as to avoid the problem that the test time is too long due to the existence of a time interval between the test times of the first output voltage, the second output voltage and the third output voltage, and in the case of the test time, the actual temperature may change too long to cause inaccurate measurement, or offset voltage variations can also result in reduced measurement accuracy. It can be understood that the shorter the test time is, the higher the accuracy of the test result is and in addition, the better the real-time performance of the test result is because the circuit parameters basically cannot change in a short time; in addition, the first time period, the second time period and the third time period are all less than or equal to 10 microseconds, the test can be completed within about 30 microseconds, and the temperature generally does not change instantaneously within a short time in the order of microseconds, so that parameters in the circuit are basically kept unchanged even if a temperature drift phenomenon exists, for example, the resistance value of the calibration resistor Rc and the offset voltage Vos are basically unchanged.

Based on the disclosure of the above embodiments, in this embodiment, the sum of the first time period, the second time period and the third time period is less than or equal to the first preset time period, and in addition, the third time period is greater than or equal to the second preset time period. In this embodiment, the first preset time period may be 50us, or 30us, or 20us, and the shorter the first preset time period is, the shorter the time period is, the temperature measurement can be completed. In addition, the third period of time is greater than or equal to a second preset period of time, which may be 0.5us, 1us, 5us, or 10us, it being understood that the third period of time cannot be too short, and if the third period of time is too short, since a period of time is required for the thermistor to respond to the temperature, the result may have been output without the resistance value of the thermistor having sufficiently changed in accordance with the change in the ambient temperature, so that the measurement is inaccurate.

Based on the disclosure of the above embodiments, in this embodiment, the first time period is earlier than the second time period, and the second time period is earlier than the third time period. First testing to obtain a first output voltage Vos, then testing to obtain a second output voltage, and finally testing to obtain a third output voltage. In this embodiment, the test of the second output voltage Vc is next to the test of the third output voltage VT, so as to avoid measurement errors caused by changes in the resistance values of the first voltage VDD, the second voltage VSS, and the feedback resistor Rf when the second output voltage Vc and the third output voltage VT are tested. In particular, if the first time period, the second time period and the third time period are consecutive in time, and the second time period is next to the third time period, the accuracy of the second output voltage and the third output voltage can be further improved, and thus the temperature obtained by the test is more accurate. In addition, the first time period is set to be earlier than the second time period, and the second time period is earlier than the third time period, so that the second time period is only next to the third time period, the third output voltage VT can be finally output, and the real-time performance of temperature measurement is better.

Based on the disclosure of the above embodiments, in this embodiment, the differential amplifier circuit may be a differential programmable gain amplifier circuit, in this embodiment, the size of the feedback resistor Rf may be changed, that is, the size of the feedback resistor Rf may be programmed, so that the gain of the differential amplifier circuit is variable. Since the calibration resistor is related to the size of the feedback resistor, it is easy to integrate the calibration resistor, and the feedback resistor is adjustable, i.e. a differential programmable gain amplifier is used, so that the user can configure the feedback resistor Rf according to the selected calibration resistor, and accordingly, the size Rf of the feedback resistor Rf is configured to be Rf < Rc | VCC/(VSS-VDD) |/2, assuming that the first output voltage Vos is ignored.

Based on the disclosure of the above embodiments, in this embodiment, the differential amplifier circuit may be a TIA (trans-impedance amplifier) circuit.

Based on the disclosure of the above embodiments, in this embodiment, the calibration resistor may be a precision resistor, for example, the calibration resistor may have a precision smaller than or equal to one thousandth, or a precision smaller than or equal to one ten thousandth. Additionally, the calibration resistor may have a temperature drift of less than or equal to 10 ppm/deg.C, with 10 ppm/deg.C representing a 10ppm (parts per million) precision change per 1 deg.C change in temperature, where parts per million (ppm) represents 10^ C^(-6). As another example, the temperature drift can be equal to or less than 1 ppm/deg.C. Referring to the foregoing embodiment, since the magnitude of the resistance value of the thermistor is related to the resistance value of the calibration resistor, and the test value of the thermistor is most accurate when the calibration resistor is not changed in the second and third time periods, it is possible to set the calibration resistor as a precision resistor, andthe temperature drift and the precision of the thermistor are limited so as to improve the test accuracy of the thermistor and further improve the temperature test accuracy.

Based on the disclosure of the above embodiments, in the present embodiment, as shown in fig. 3A, the first voltage VDD is provided by the differential amplifier circuit 301, and it can be understood that the differential amplifier 307 can provide the first voltage VDD, so that the first voltage VDD can be provided to the inverting input terminal of the amplifier circuit. In addition, referring to fig. 3F, the first voltage VDD may also be provided by the first voltage generating circuit 309. In addition, the second voltage VSS may also be provided by a second voltage generating circuit, or a power module is provided, which may be used for generating the first voltage and the second voltage, and is not described herein again. The temperature measuring circuit provided by this embodiment may also be referred to as a constant voltage driving temperature measuring circuit, and the constant voltage source may provide a first voltage, for example, a common mode voltage, by adopting a constant voltage source driving manner. In this embodiment, the input signals of the differential amplifier are differential signals Vin and Vip, and the output signals are differential signals Von and Vop, where Vin is the first voltage VDD.

Based on the disclosure of the foregoing embodiments, this embodiment further provides a temperature measurement and light measurement circuit, please refer to fig. 7A, where the temperature measurement and light measurement circuit includes any one of the temperature measurement circuits in the foregoing embodiments, and in addition, may further include a PD (photo diode), specifically, may also include a plurality of photodiodes 711, where a current flowing through the photodiodes is represented by Ipd, the plurality of photodiodes 711 may be arranged in series or in parallel, and the temperature measurement and light measurement circuit may also not include a Photodiode, that is, the photodiodes may be connected to the temperature measurement and light measurement circuit as an external device, so that a user may select a Photodiode to be connected to the temperature measurement and light measurement circuit according to a requirement. The switch circuit 710 includes at least one switch unit so that the non-inverting input terminal of the differential amplifier 707 is connected to the front stage of the photodiode 711 for a fourth time period, at which time the differential amplifier circuit 701 outputs a fourth output voltage, and then the conversion circuit 708 may output a light intensity signal according to the fourth output voltage. Specifically, when the contact of the switching circuit 710 is connected to the contact 4, the front stage of the photodiode is connected to the non-inverting input terminal of the differential amplifier, and the fourth output voltage Vout of the output after Ipd is amplified by the differential amplifier is assumed to be Vp, Vp = Ipd × 2Rf, where 2Rf is the amplification factor of the differential amplifier circuit for the current Ipd, and the conversion circuit can calculate the light intensity according to the magnitude of Vp. Similarly, the analog-to-digital converter 703 converts the Vout into a digital signal, and the control circuit 704 processes the digital signal to obtain a light intensity signal, and then outputs the light intensity signal to the display screen for displaying. The thermistor 700, the calibration resistor 705, the differential amplifier circuit 701, the analog-to-digital conversion circuit 703 and the control circuit 704 in this embodiment are the same as or similar to those in the previous embodiments, and are not described herein again. It can be understood that, in this embodiment, the temperature may be tested first, the light intensity may also be tested first, or the temperature may also be tested after the light intensity is tested first, which physical quantity is specifically tested and how often the test is performed is determined by the user's requirement, in addition, the control circuit MCU may further process the light intensity signal obtained by the test to obtain the heart rate signal or the blood oxygen signal, and finally the output circuit outputs the heart rate signal or the blood oxygen signal, and the output circuit may be connected with the control circuit, the conversion circuit may include that the output circuit is specific, and the output circuit may be connected with the MCU, and the output circuit may include a display screen and/or a voice output circuit. The temperature measurement and light measurement circuit that this application embodiment provided can realize measuring temperature and light intensity with less components and parts, and when testing temperature, switch circuit, difference amplifier circuit and converting circuit can be used for testing temperature, and when testing light intensity, switch circuit, difference amplifier circuit and converting circuit can be used for testing light intensity, and it can be understood that test temperature and test light intensity have multiplexed partly circuit to make cost greatly reduced.

Based on the disclosure of the above embodiments, in this embodiment, the control circuit 704 may further be connected to the switch circuit 710, and is configured to control on and off of the switch unit in the switch circuit 710, so as to implement temperature measurement. Or an additional switch control circuit can be arranged and connected with the switch circuit to control the on and off time sequence of the switch circuit, so as to realize temperature measurement.

Based on the disclosure of the above embodiments, in the present embodiment, as shown in fig. 7A, the second voltage Vss is connected to the subsequent stage of the photodiode 711, and specifically, the second voltage may also be GND.

Based on the disclosure of the above embodiments, in the present embodiment, referring to fig. 7B, the converting circuit 708 includes a current determiner 713 and a light intensity determiner 712, the current determiner 713 is connected to the light intensity determiner 712;

the current determiner 713 is configured to output a current signal through the photodiode according to the fourth output voltage; the light intensity determiner 712 is configured to output a light intensity signal based on the current signal through the photodiode. In this embodiment, the current determiner may directly process the fourth output voltage, or, in combination with the foregoing embodiments, the control circuit 704 may include a current determiner 713 and an optical intensity determiner 712, the analog-to-digital conversion circuit 703 may be connected to the current determiner 713, and the current determiner may process the fourth output voltage converted by the analog-to-digital conversion circuit, for example, if the analog-to-digital conversion circuit 703 converts the fourth output voltage into a fourth output signal, the current determiner 713 may process the fourth output signal to obtain a current signal passing through the photodiode, and the optical intensity determiner outputs an optical intensity signal according to the current signal passing through the photodiode. In addition, the analog-to-digital conversion circuit 703 may also be disposed between the current determiner and the light intensity determiner, specifically, the current determiner outputs a current signal passing through the photodiode according to the fourth output voltage, the current signal is subjected to digital-to-analog conversion by the analog-to-digital converter to form a digital current signal, and the light intensity determiner is configured to process the digital current signal to output a light intensity signal.

Based on the disclosure of the above embodiments, in this embodiment, the current determiner includes a third divider, and the third divider is configured to calculate the current signal as the fourth output voltage divided by twice the resistance value of the feedback resistor. In this embodiment, the current determiner may further include a third multiplier for calculating a resistance value of the double feedback resistor.

Based on the disclosure of the above embodiments, in this embodiment, as shown in fig. 8, the light measuring method corresponding to the temperature measurement and light measurement circuit includes the following steps:

s801: in a fourth time period, the non-inverting input end of the differential amplifier is connected with the front stage of the photodiode so that the differential amplifying circuit outputs a fourth output voltage in the fourth time period;

s802: the conversion circuit outputs a light intensity signal according to the fourth output voltage.

Based on the disclosure of the above embodiments, in this embodiment, further referring to fig. 9, the determining the magnitude of the current passing through the photodiode according to the fourth output voltage may include the following steps:

s901: determining the current passing through the photodiode according to the fourth output voltage;

s902: and outputting a light intensity signal according to the current passing through the photodiode.

Based on the disclosure of the above embodiments, in the present embodiment, determining the magnitude of the current passing through the photodiode according to the fourth output voltage includes: the current passing through the photodiode is the fourth output voltage divided by twice the resistance of the feedback resistor. According to the content of the foregoing embodiment, since Vp = Ipd × 2Rf, Ipd = Vp/(2 × Rf) can be obtained.

The present embodiment further provides a chip, which includes the temperature measurement circuit in the foregoing embodiment or the temperature measurement and light measurement circuit in the foregoing embodiment. According to the chip provided by the embodiment, the temperature signal is obtained by the first output voltage output by the no-load time difference amplifying circuit at the non-inverting input end of the differential amplifier, the second output voltage output by the time difference amplifying circuit at the first end of the calibration resistor connected to the non-inverting input end of the differential amplifier, and the third output voltage output by the time difference amplifying circuit at the first end of the thermistor connected to the non-inverting input end of the differential amplifier, so that the problem of inaccurate temperature measurement in the prior art is solved.

The present embodiment further provides a module, which includes a chip in the foregoing embodiments, the chip is connected to a substrate, and the substrate may be a Printed Circuit Board (PCB) or a Flexible Printed Circuit Board (FPC). In addition, the module also comprises a thermistor and a calibration resistor, and in addition, the module also can comprise a photodiode. The module provided by this embodiment obtains a temperature signal by the first output voltage output by the non-load time difference amplification circuit at the non-inverting input end of the differential amplifier, the second output voltage output by the first end time difference amplification circuit when the non-inverting input end of the differential amplifier is connected to the calibration resistor, and the third output voltage output by the first end time difference amplification circuit when the non-inverting input end of the differential amplifier is connected to the thermistor, so that the problem of inaccurate temperature measurement in the prior art is solved.

This embodiment still provides an electronic equipment, including shell and the chip of the aforesaid embodiment, the chip sets up in the shell, and is specific, this electronic equipment includes portable equipment such as bracelet, wrist-watch, cell-phone, electronic thermometer. In the electronic device provided in this embodiment, the temperature signal is obtained by the first output voltage output by the no-load time difference amplification circuit at the non-inverting input end of the differential amplifier, the second output voltage output by the first end time difference amplification circuit when the non-inverting input end of the differential amplifier is connected to the calibration resistor, and the third output voltage output by the first end time difference amplification circuit when the non-inverting input end of the differential amplifier is connected to the thermistor.

It should be noted that the above method embodiments of the present application may be applied to or implemented by a processor. The processor may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method embodiments may be performed by integrated logic circuits of hardware in a processor or instructions in the form of software. The processor may be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, or discrete hardware components. The various methods, steps, and logic blocks disclosed in the embodiments of the present application may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in ram, flash memory, rom, prom, or eprom, registers, etc. storage media as is well known in the art. The storage medium is located in a memory, and a processor reads information in the memory and completes the steps of the method in combination with hardware of the processor.

It will be appreciated that the memory in the embodiments of the subject application can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. The non-volatile memory may be a read-only memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an electrically Erasable EPROM (EEPROM), or a flash memory. Volatile memory can be Random Access Memory (RAM), which acts as external cache memory. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), double data rate SDRAM, enhanced SDRAM, SLDRAM, Synchronous Link DRAM (SLDRAM), and direct rambus RAM (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

It should be understood that in the embodiment of the present application, "B corresponding to a" means that B is associated with a, from which B can be determined. It should also be understood that determining B from a does not mean determining B from a alone, but may also be determined from a and/or other information.

In addition, the term "and/or" herein is only one kind of association relationship describing an associated object, and means that there may be three kinds of relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a read-only memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (27)

1. A temperature measurement circuit is characterized in that: the circuit comprises a switch circuit, a differential amplification circuit and a conversion circuit;

the thermistor and the calibration resistor are connected with the switch circuit, the switch circuit is connected with the differential amplification circuit, and the differential amplification circuit is connected with the conversion circuit;

the differential amplification circuit comprises a differential amplifier;

the switch circuit comprises at least one switch unit so that the non-inverting input end of the differential amplifier is unloaded in a first time period, the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor in a second time period, and the non-inverting input end of the differential amplifier is connected with the first end of the thermistor in a third time period;

when the non-load of the non-inverting input end of the differential amplifier is carried out, the differential amplifier circuit outputs a first output voltage; when the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor, the differential amplification circuit outputs a second output voltage; when the non-inverting input end of the differential amplifier is connected with the first end of the thermistor, the differential amplifier circuit outputs a third output voltage;

the conversion circuit is used for outputting temperature signals according to the first output voltage, the second output voltage and the third output voltage.

2. The thermometric circuit of claim 1, wherein the switching circuit comprises a first resistance determiner and a first temperature determiner; the first resistance value determiner is connected with the first temperature determiner and is used for outputting resistance value signals of the thermistor according to the first output voltage, the second output voltage and the third output voltage;

the first temperature determiner is configured to convert the resistance signal into the temperature signal.

3. The thermometric circuit of claim 2, wherein the first resistance determiner comprises a first subtractor, a first multiplier, and a first divider;

the first subtractor is configured to calculate a first difference and a second difference, where the first difference is a difference between the second output voltage and the first output voltage, and the second difference is a difference between the third output voltage and the first output voltage;

the first multiplier is used for calculating a first product, and the first product is the product of the first difference value and the resistance value of the calibration resistor;

the first divider is used for calculating to obtain the resistance value signal, and the resistance value signal is the first product divided by the second difference.

4. The temperature measuring circuit of claim 2, wherein the conversion circuit further comprises a first analog-to-digital converter, the first analog-to-digital converter being coupled to the first resistance value determiner, the first analog-to-digital converter being configured to convert the resistance value signal into a digital resistance value signal, and the first temperature determiner being configured to convert the digital resistance value signal into the temperature signal.

5. The thermometric circuit of claim 1, wherein the conversion circuit comprises a second analog-to-digital conversion circuit and a control circuit; the second analog-to-digital conversion circuit is connected with the control circuit;

the second analog-to-digital conversion circuit is used for performing analog-to-digital conversion on the first output voltage, the second output voltage and the third output voltage to respectively obtain a first digital signal, a second digital signal and a third digital signal;

the control circuit is configured to convert the first digital signal, the second digital signal, and the third digital signal into a temperature signal.

6. The thermometric circuit of claim 5, wherein the control circuit comprises: a second resistance determiner and a second temperature determiner;

the second resistance determiner is connected with the second temperature determiner and is used for converting the first digital signal, the second digital signal and the third digital signal into a digital resistance signal of the thermistor;

the second temperature determiner is configured to convert the digital resistance signal into the temperature signal.

7. The thermometric circuit of claim 6, wherein the second resistance determiner comprises a second subtractor, a second multiplier, and a second divider;

the second subtractor is configured to calculate a third difference and a fourth difference, where the third difference is a difference between the second digital signal and the first digital signal, and the fourth difference is a difference between the third digital signal and the first digital signal;

the second multiplier is used for calculating a second product, and the second product is the product of the third difference value and the resistance value of the calibration resistor;

the second divider is used for calculating to obtain the digital resistance signal, and the digital resistance signal is the second product divided by the fourth difference.

8. The thermometric circuit according to any one of claims 1 to 7, wherein the inverting input terminal of the differential amplifier is connected to a first voltage; the second end of the thermistor is connected with a second voltage; the second end of the calibration resistor is connected with the second voltage; the second voltage is greater than or less than the first voltage.

9. The temperature measurement circuit of claim 8, wherein the differential amplifier circuit further comprises a feedback resistor, two ends of the feedback resistor are respectively connected to the non-inverting input terminal and the inverting output terminal of the differential amplifier, the resistance value of the calibration resistor is greater than twice the resistance value of the feedback resistor multiplied by a first preset absolute value, and the first preset absolute value is an absolute value of a quotient obtained by dividing a difference value between the first voltage and the second voltage by a power supply voltage; the feedback resistor is a non-sensitive resistor.

10. The temperature measuring circuit according to claim 9, wherein when the non-load input terminal of the differential amplifier is no-load, the gain of the differential amplifier circuit is 0; when the non-inverting input end of the differential amplifier is connected with the first end of the calibration resistor, the gain of the differential amplifier circuit is 2 times of the resistance value of the feedback resistor divided by the resistance value of the calibration resistor; when the non-inverting input end of the differential amplifier is connected with the first end of the thermistor, the gain of the differential amplifier circuit is 2 times of the resistance value of the feedback resistor divided by the resistance value of the thermistor.

11. The thermometric circuit of claim 9, wherein said second voltage is ground; the first voltage is a common mode voltage; the resistance value of the feedback resistor is smaller than that of the calibration resistor.

12. The temperature measurement circuit according to any one of claims 1 to 7, wherein the switching circuit comprises a first switching unit, a second switching unit;

during the first period of time, the first switch unit and the second switch unit are both in an off state; when the first switch unit and the second switch unit are both in an off state, the non-load input end of the differential amplifier is in no-load state, so that the differential amplification circuit outputs the first output voltage;

in the second time period, the first switch unit is in a closed state; when the first switch unit is in a closed state, the non-inverting input terminal of the differential amplifier is connected with the first end of the calibration resistor, so that the differential amplification circuit outputs the second output voltage;

in the third time period, the second switch unit is in a closed state; when the second switch unit is in a closed state, the non-inverting input terminal of the differential amplifier is connected to the first terminal of the thermistor, so that the differential amplifier circuit outputs the third output voltage.

13. The temperature measurement circuit according to any one of claims 1 to 7, wherein the switch circuit is a one-out-of-three switch circuit, and the one-out-of-three switch circuit is configured to switch the connection state of the non-inverting input terminal of the differential amplifier in the first time period, the second time period and the third time period, respectively, so that the non-inverting input terminal of the differential amplifier is unloaded or connected to the first terminal of the calibration resistor or connected to the first terminal of the thermistor.

14. The thermometric circuit of any of claims 1-7, wherein the first time period, the second time period, and the third time period are consecutive in time; the sum of the first time period, the second time period and the third time period is less than or equal to a first preset time length; the third time period is greater than or equal to a second preset time period.

15. The thermometric circuit of claim 14, wherein the first predetermined duration is 30 microseconds; the second preset time is 1 microsecond.

16. The thermometric circuit of any of claims 1-7, wherein the first time period, the second time period, and the third time period are each less than or equal to 10 microseconds in length.

17. The thermometric circuit of any of claims 1-7, wherein the first time period is earlier than the second time period, which is earlier than the third time period; or

The second time period is earlier than the third time period, which is earlier than the first time period.

18. The thermometric circuit of any of claims 1-7, wherein the calibration resistor is a non-sensitive resistor.

19. The thermometric circuit according to any one of claims 1-7, wherein the calibration resistor is a precision resistor, the temperature drift of the calibration resistor is less than or equal to 10ppm/° C, and the precision of the calibration resistor is less than or equal to one thousandth.

20. The thermometric circuit of any one of claims 1-7, wherein the differential amplification circuit is a differential programmable gain amplification circuit.

21. A temperature measurement and light measurement circuit, characterized by comprising the temperature measurement circuit according to any one of claims 1 to 20;

the switching circuit includes at least one switching unit to connect a non-inverting input terminal of the differential amplifier to a previous stage of the photodiode for a fourth time period; when the non-inverting input end of the differential amplifier is connected with the front stage of the photodiode, the differential amplification circuit outputs a fourth output voltage;

and the conversion circuit outputs a light intensity signal according to the fourth output voltage.

22. The temperature-measuring and light-measuring circuit according to claim 21, wherein a second voltage is connected to a subsequent stage of the photodiode; the second voltage is a ground voltage.

23. The temperature-measuring and light-measuring circuit according to claim 21 or 22, wherein the conversion circuit includes a current determiner and a light intensity determiner; the current determiner is connected with the light intensity determiner;

the current determiner is used for outputting a current signal passing through the photodiode according to the fourth output voltage;

the light intensity determiner is used for outputting the light intensity signal according to the current signal passing through the photodiode.

24. The thermometric light measuring circuit of claim 23, wherein the current determiner comprises a third divider configured to calculate the current signal as the fourth output voltage divided by twice the resistance of the feedback resistor.

25. A chip comprising the thermometry circuit of any one of claims 1 to 20 or comprising the thermometry photometry circuit of any one of claims 21 to 24.

26. A module, comprising: a substrate, the thermistor, the calibration resistor and the chip of claim 25; the chip is connected with the substrate.

27. An electronic device, comprising: a housing and a chip as claimed in claim 25, said chip being disposed within said housing.

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