CN113758606A - Temperature sensor and temperature measuring equipment - Google Patents
Temperature sensor and temperature measuring equipment Download PDFInfo
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- CN113758606A CN113758606A CN202111197789.0A CN202111197789A CN113758606A CN 113758606 A CN113758606 A CN 113758606A CN 202111197789 A CN202111197789 A CN 202111197789A CN 113758606 A CN113758606 A CN 113758606A
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K13/00—Thermometers specially adapted for specific purposes
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
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Abstract
The invention provides a temperature sensor which comprises a self-detection unit, a current source unit and an analog-to-digital conversion unit, wherein the current source unit is connected with the analog-to-digital conversion unit; the self-detection unit is connected with the current source unit through the self-detection switch and comprises a first self-detection current source and a second self-detection current source, the first self-detection current source and the second self-detection current source are used for enabling the analog-to-digital conversion unit to output a second quantized output value, and the second quantized output value is used for detecting whether the temperature sensor fails or not. The self-detection unit is arranged, the self-detection function of the current type temperature sensor is realized, the self-detection unit is simple in structure, small in occupied chip area, low in cost, high in self-detection accuracy and high in stability. The self-detection unit is accurate and stable in self-detection of the temperature sensor, and accuracy of the self-detection of the temperature sensor is improved. The invention also provides temperature measuring equipment comprising the temperature sensor.
Description
Technical Field
The invention relates to the technical field of temperature detection, in particular to a temperature sensor and temperature measuring equipment.
Background
With the development of integrated circuit technology, the process feature size is continuously reduced, the chip integration level is continuously improved, the chip power density is higher and higher, and besides the emphasis on heat dissipation and low power consumption design, temperature monitoring also becomes an indispensable basic function. For analog circuits, many circuit blocks and functions are more sensitive to temperature changes, so the operation configuration needs to be changed in real time according to the temperature change of the chip. In addition, in an application scenario with a high requirement on reliability, the temperature sensor circuit is also required to have a self-detection function to detect whether the temperature sensor itself fails. And when the circuit failure is detected, feeding back the result in time.
The temperature range detected by the temperature sensor is large, usually-40-155 ℃, and the self-detection of the temperature sensor is required to confirm whether the working state of the temperature sensor is normal under an unknown temperature condition. This requires that the temperature sensor output a quantized output value that is not correlated with temperature changes during the self-test mode, and that the temperature sensor be deemed to be currently in a normal operating state if the quantized output value is within an expected range, and that the temperature sensor be deemed to be currently in a failed state otherwise. Therefore, the fixed quantized output value in the self-test mode is required to fall within the expected range as stably as possible, and the expected value range should be as small as possible, and the requirement for the quantized output value is particularly high in the self-test of the high-precision temperature sensor.
In the prior art, an additional detection circuit or a detection device is added to detect whether the temperature sensor fails, so that the cost is high.
The invention patent with publication number CN 105651416a discloses a current type temperature sensor circuit, which adopts a current mode to convert the negative temperature coefficient voltage outputted by a reference into a negative temperature coefficient current, performs proportional integration with the positive temperature coefficient current generated by the reference, compares the voltage value after integration with the reference voltage in a comparator and generates a digital signal, samples the generated digital signal by a digital clock and outputs the digital signal, and simultaneously feeds back and controls the integral coefficient of the proportional integration, and can calculate the current temperature by calculating the number of high levels or low levels in unit time of the sampling output. The integrated circuit is charged and discharged by skillfully utilizing the positive temperature coefficient current and the negative temperature coefficient circuit, the testing requirements of different use environments, different parameters of the circuit or different temperature detection ranges are met by adjusting the proportional coefficient of the integrated circuit and the operation combination of the positive temperature coefficient current and the negative temperature coefficient current, the whole circuit is simple, the physical examination is small, and the multi-point testing requirements can be met. However, the current type temperature sensor circuit is not provided with a detection circuit, so that the current type temperature sensor circuit does not have a self-checking function, and whether the current type temperature sensor fails or not cannot be judged.
Therefore, it is necessary to provide a temperature sensor and a temperature measuring device to solve the above problems in the prior art.
Disclosure of Invention
The invention aims to provide a temperature sensor and temperature measuring equipment, and aims to solve the problem that the temperature sensor in the prior art has no self-checking circuit or the self-checking circuit is high in cost.
In order to achieve the above object, the temperature sensor of the present invention includes a self-detection unit, a current source unit and an analog-to-digital conversion unit, wherein the current source unit is connected to the analog-to-digital conversion unit;
the analog-to-digital conversion unit comprises an integrator, a quantizer and a filter, wherein the output end of the current source unit is connected with the input end of the integrator, the output end of the integrator is connected with the input end of the quantizer, and the output end of the quantizer is connected with the input end of the filter;
the self-checking unit with the current source unit is connected through the self-checking switch, the self-checking unit includes first self-checking current source and second self-checking current source, the positive pole of first self-checking current source is connected the negative pole of second self-checking current source, the anodal ground connection of second self-checking current source, first self-checking current source with second self-checking current source is used for making analog-to-digital conversion unit output second quantization output value, second quantization output value is used for detecting whether temperature sensor is inefficacy.
The temperature sensor has the advantages that:
a self-detection unit is arranged and comprises a first self-detection current source and a second self-detection current source, the first self-detection current source and the second self-detection current source are used for enabling the analog-to-digital conversion unit to output a second quantized output value, and the second quantized output value is used for detecting whether the temperature sensor fails or not, so that the self-detection function of the current type temperature sensor is realized. The self-detection unit has the advantages of simple structure, small occupied chip area, low cost, high self-detection accuracy and high stability. The self-detection unit is accurate and stable in self-detection of the temperature sensor, and accuracy of self-detection of the temperature sensor is improved.
Preferably, the current source unit includes a first current source, a first control switch, a second control switch and a second current source, an anode of the first current source is sequentially connected to the first control switch, the second control switch and a cathode of the second current source, an anode of the second current source is grounded, and a node between the first control switch and the second control switch is connected to an input end of the integrator.
Further preferably, a node between the first control switch and the second control switch is further connected to one end of the self-checking switch, and the other end of the self-checking switch is connected to a node between the first self-checking current source and the second self-checking current source.
Preferably, when the self-checking switch is turned off, the temperature sensor enters a temperature detection mode;
after the temperature sensor enters a temperature detection mode, the first current source outputs a first temperature current and the second current source outputs a second temperature current to the analog-to-digital conversion unit;
the analog-to-digital conversion unit receives the first temperature current and the second temperature current, and then quantizes the first temperature current and the second temperature current to obtain a first quantized output value, wherein the first quantized output value is related to both the first temperature current and the second temperature current. The temperature sensor has the advantages that when the temperature sensor detects the temperature, the self-checking switch is switched off, so that the first self-checking current source and the second self-checking current source cannot influence the detection process and result of the temperature sensor, and the stable temperature detection process of the temperature sensor is ensured.
Preferably, when the self-checking switch is closed, the temperature sensor enters a self-checking mode;
after the temperature sensor enters a self-test mode, the first self-test current source outputs the first self-test current, the second self-test current source outputs the second self-test current, the first current source outputs a first temperature current, and the second current source outputs a second temperature current to the analog-to-digital conversion unit;
after receiving the first self-detection current, the second self-detection current, the first temperature current and the second temperature current, the analog-to-digital conversion unit performs quantization processing on the first self-detection current, the second self-detection current, the first temperature current and the second temperature current to obtain a second quantized output value;
when the second quantized output value is not related to the first temperature current or the second temperature current, judging that the temperature sensor is effective;
determining that the temperature sensor is disabled when the second quantized output value is related to either of the first temperature current and the second temperature current. The temperature detection device has the advantages that the temperature detection mode or the self-checking mode of the temperature sensor can be flexibly switched according to the requirement, and when the temperature is required to be detected, the self-checking switch is switched off; when self-checking is needed, the self-checking switch is closed, so that the temperature sensor enters a self-checking mode, the mode is switched simply and quickly, and the self-checking efficiency of the temperature sensor is improved. And whether the temperature sensor fails or not is judged through the second quantitative output value, the judging method is quick and effective, the efficiency of judging whether the temperature sensor fails or not is improved, and the self-checking efficiency of the temperature sensor is further improved.
Further preferably, the first self-checking current is the second temperature current
The second self-checking current is the first temperature current
Multiple, N is a real number other than 0 and 1.
Preferably, the quantizer includes a comparator, a first feedback signal line, a second feedback signal line and an inverter, an output terminal of the comparator is connected to the second control switch through the first feedback signal line, a node on the first feedback signal line is connected to an input terminal of the inverter, and an output terminal of the inverter is connected to the first control switch through the second feedback signal line;
and the comparator outputs a result and feeds the result back to the second control switch and the first control switch so as to respectively control the second control switch and the first control switch.
Preferably, the integrator includes an operational amplifier, a capacitor and a reset switch, a negative input end of the operational amplifier is connected to a node between the first control switch and the second control switch, a positive input end of the operational amplifier is connected to a positive input end of the comparator, and an output end of the operational amplifier is connected to a negative input end of the comparator;
the two ends of the reset switch are respectively connected with the negative input end of the operational amplifier and the output end of the operational amplifier, and the capacitor is connected with the reset switch in parallel.
Further preferably, the integrator further includes a voltage source, an anode of the voltage source is connected to the positive input end of the operational amplifier and the positive input end of the comparator, and a cathode of the voltage source is grounded.
The invention also provides temperature measuring equipment comprising the temperature sensor.
The temperature measuring equipment has the beneficial effects that:
the temperature measuring equipment comprises the temperature sensor, and the self-detection function of the current type temperature sensor is realized.
Drawings
FIG. 1 is a circuit diagram of a temperature sensor according to an embodiment of the present invention;
fig. 2 is a circuit diagram of a bandgap reference voltage source according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. As used herein, the word "comprising" and similar words are intended to mean that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items.
In order to solve the problems in the prior art, embodiments of the present invention provide a temperature sensor and a temperature measuring device.
Fig. 1 is a circuit diagram of a temperature sensor according to the present invention, and referring to fig. 1, the temperature sensor according to the present invention includes a self-detection unit 2, a current source unit 3, and an analog-to-digital conversion unit 1, where the current source unit 3 is connected to the analog-to-digital conversion unit 1;
the analog-to-digital conversion unit 1 comprises an integrator 4, a quantizer 5 and a filter 6, wherein the output end of the current source unit 3 is connected with the input end of the integrator 4, the output end of the integrator 4 is connected with the input end of the quantizer 5, and the output end of the quantizer 5 is connected with the input end of the filter 6;
in some embodiments, filter 1 may be a down-sampling filter.
The self-detection unit 2 is connected with the current source unit 3 through a self-detection switch 22, the self-detection unit 2 includes a first self-detection current source 20 and a second self-detection current source 21, the anode of the first self-detection current source 20 is connected with the cathode of the second self-detection current source 21, the anode of the second self-detection current source 21 is grounded, the first self-detection current source 20 and the second self-detection current source 21 are used for enabling the analog-to-digital conversion unit 1 to output a second quantized output value, and the second quantized output value is used for detecting whether the temperature sensor fails or not.
The temperature sensor of the invention has the advantages that:
the self-detection unit 2 is arranged and comprises a first self-detection current source 20 and a second self-detection current source 21, the first self-detection current source 20 and the second self-detection current source 21 are used for enabling the analog-to-digital conversion unit 1 to output a second quantized output value, and the second quantized output value is used for detecting whether the temperature sensor fails or not, so that the self-detection function of the current type temperature sensor is achieved. The self-detection unit 2 has the advantages of simple structure, small occupied chip area, low cost, high self-detection accuracy and high stability. The self-detection unit 2 is accurate and stable in self-detection of the temperature sensor, and accuracy of the self-detection of the temperature sensor is improved.
As a preferred embodiment of the present invention, the current source unit 3 includes a first current source 30, a first control switch 31, a first control switch 32, and a second current source 33, wherein the positive electrode of the first current source 30 is connected to the negative electrodes of the first control switch 31, the first control switch 32, and the second current source 33 in this order, the positive electrode of the second current source 33 is grounded, and the node between the first control switch 31 and the first control switch 32 is connected to the input terminal of the integrator 4.
In a preferred embodiment of the present invention, the node between the first control switch 31 and the first control switch 32 is further connected to one end of the self-test switch 22, and the other end of the self-test switch 22 is connected to the node between the first self-test current source 20 and the second self-test current source 21.
As a preferred embodiment of the present invention, when the self-test switch 22 is turned off, the temperature sensor enters a temperature detection mode;
after the temperature sensor enters the temperature detection mode, the first current source 30 outputs a first temperature current and the second current source 33 outputs a second temperature current to the analog-to-digital conversion unit 1; the current value of the first temperature current is IPTATSecond temperature ofThe current value of the current is ICTAT；
The analog-to-digital conversion unit 1 receives the first temperature current and the second temperature current, and then performs quantization processing on the first temperature current and the second temperature current to obtain a first quantized output value. The first quantized output value μ is expressed as
From the above expression of the first quantized output value μ, the first quantized output value μ and the first temperature current IPTATAnd the second temperature current.
The advantage is that when the temperature sensor detects the temperature, the self-checking switch 22 is turned off, so that the first self-checking current source 20 and the second self-checking current source 21 do not affect the detection process and result of the temperature sensor, and the stable temperature detection process of the temperature sensor is ensured.
As a preferred embodiment of the present invention, when the self-test switch 22 is closed, the temperature sensor enters the self-test mode;
after the temperature sensor enters the self-test mode, the first self-test current source 20 outputs a first self-test current, the second self-test current source 21 outputs a second self-test current, the first current source 30 outputs a first temperature current, and the second current source 33 outputs a second temperature current to the analog-to-digital conversion unit 1;
after receiving the first self-detection current, the second self-detection current, the first temperature current and the second temperature current, the analog-to-digital conversion unit 1 quantizes the first self-detection current, the second self-detection current, the first temperature current and the second temperature current to obtain a second quantized output value;
when the second quantized output value is not related to the first temperature current and the second temperature current, the temperature sensor is judged to be effective;
and when the second quantized output value is related to any one of the first temperature current and the second temperature current, determining that the temperature sensor is failed. The temperature detection device has the advantages that the temperature detection mode or the self-detection mode of the temperature sensor can be flexibly switched according to the requirement, and when the temperature is required to be detected, the self-detection switch 22 is switched off; when self-checking is needed, the self-checking switch 22 is closed, so that the temperature sensor enters a self-checking mode, the mode is switched simply and quickly, and the self-checking efficiency of the temperature sensor is improved. And whether the temperature sensor fails or not is judged through the second quantitative output value, the judging method is quick and effective, the efficiency of judging whether the temperature sensor fails or not is improved, and the self-checking efficiency of the temperature sensor is improved.
In a preferred embodiment of the present invention, the first self-test current is a second temperature current
The second self-checking current being the first temperature current
Multiple, N is a real number other than 0 and 1.
The advantages are that: outputs a first self-test current through a first self-test current source 20
The second self-test current source 21 outputs a second self-test current
Therefore, the temperature sensor outputs a quantized output value irrelevant to the temperature current, and the self-detection function of the temperature sensor is realized.
In some embodiments, after the temperature sensor enters the self-test mode, the first current source 30 outputs a first temperature current having a current value IPTATThe second current source 33 outputs a second temperature current with a current value ICTATThe first self-test current source 20 outputs a first self-test current having a current value of
The second self-test current source 21 outputs a second self-test current having a current value of
N is a real number other than 0 and 1. The temperature sensor outputs a second quantized output value, which is expressed as
The right-hand side score of the above expression of the quantized output value is simplified by the numerator denominator,
obtaining the second quantized output value μ' and the first temperature current ICTATAnd a second temperature current ICTATAll are irrelevant, thereby realizing the self-detection function of the temperature sensor.
Referring to fig. 1, a quantizer 5 according to a preferred embodiment of the present invention includes a comparator 50, a first feedback signal line 51, a second feedback signal line 52, and an inverter 53, wherein an output terminal of the comparator 50 is connected to the second control switch 32 through the first feedback signal line 51, a node on the first feedback signal line 51 is connected to an input terminal of the inverter 53, and an output terminal of the inverter 53 is connected to the first control switch 31 through the second feedback signal line 52;
the comparator 50 outputs the result and feeds the result back to the second control switch 32 and the first control switch 31 to control the second control switch 32 and the first control switch 31, respectively.
Referring to fig. 1, the integrator 4 includes an operational amplifier 40, a capacitor 41 and a reset switch 42, a negative input terminal of the operational amplifier 40 is connected to a node between the first control switch 31 and the second control switch 32, the capacitor 41 is connected in series between the negative input terminal of the operational amplifier 40 and an output terminal of the operational amplifier 40, a positive input terminal of the operational amplifier 40 is connected to a positive input terminal of the comparator 50, an output terminal of the operational amplifier 40 is connected to the negative input terminal of the comparator 50, and the capacitor 41 is connected in parallel to the reset switch 42.
Referring to fig. 1, the integrator 4 further includes a voltage source 43, a positive pole of the voltage source 43 is connected to the positive input terminal of the operational amplifier 40 and the positive input terminal of the comparator 50, and a negative pole of the voltage source 43 is grounded.
To better understand the working principle of the temperature sensor of the present invention, the working principle of the temperature sensor of the present invention is explained below in conjunction with the working principles of the voltage-type temperature sensor and the current-type temperature sensor.
To better understand the working principle of the self-detecting current-mode temperature sensor of the present invention, the working principle of the self-detecting current-mode temperature sensor of the present invention is explained below in conjunction with the working principles of the voltage-mode temperature sensor and the current-mode temperature sensor.
The voltage type temperature sensor comprises a band gap reference voltage source and an analog-to-digital converter, wherein the band gap reference voltage source is connected with the analog-to-digital converter and used for providing voltage for the analog-to-digital converter, and the analog-to-digital converter is used for outputting a quantized output value which is in direct proportion to temperature. Fig. 2 is a circuit diagram of a bandgap reference voltage source, and as shown in fig. 2, the bandgap reference voltage source 8 includes a start circuit 80, an output terminal of the start circuit 80 is connected to a drain of a first PMOS transistor PM1 and a first resistor R1, a first end of a first resistor R1 is connected to a drain of a first PMOS transistor PM1, a second end of the first resistor R1 is connected to an emitter of a first triode Q1, a collector of the first triode Q1 is connected to a common ground terminal VSS, and a base of the first triode Q1 is shorted with the collector; the source electrode of the first PMOS tube PM1 is connected with a power voltage end VDD, and the grid electrode of the first PMOS tube PM1 is connected with the grid electrode of the second PMOS tube PM 2;
the source electrode of the second PMOS pipe PM2 is connected with a power supply voltage end VDD, the drain electrode of the second PMOS pipe PM2 is connected with the emitting electrode of a second triode Q2, the collector electrode of the second triode Q2 is connected with a common ground terminal VSS, and the base electrode of the second triode Q2 is in short circuit with the collector electrode;
a node x between the first end of the first resistor R1 and the drain of the first PMOS transistor PM1 is further connected to the positive input terminal of the first operational amplifier 81, the negative input terminal of the first operational amplifier 81 is connected to a node y between the drain of the second PMOS transistor PM2 and the emitter of the second transistor Q2, and the first operational amplifierThe output end of the operational amplifier 81 is connected with the grid of the first PMOS tube PM1 and the grid of the second PMOS tube PM2, the output end of the operational amplifier 81 is further connected with the grid of the third PMOS tube PM3 and the grid of the fourth PMOS tube PM4, the source of the third PMOS tube PM3 and the source of the fourth PMOS tube PM4 are both connected with a power voltage end VDD, and the drain of the second PMOS tube PM2, the drain of the third PMOS tube PM3 and the drain of the fourth PMOS tube PM4 are all used for outputting current IPTAT；
The drain electrode of the third PMOS tube PM3 is connected with the first end of the second resistor R2, the voltage output end VREF is connected between the drain electrode of the third PMOS tube PM3 and the first end of the second resistor R2, the second end of the second resistor R2 is connected with the emitter electrode of the third triode Q3, the collector electrode of the third triode Q3 is connected with the common ground terminal VSS, and the base electrode of the third triode Q3 is in short circuit with the collector electrode; the second end of the second resistor R2 and the emitter of the third transistor Q3 are connected to the positive input end of the second operational amplifier 82, the negative input end of the second operational amplifier 82 is connected to the first end of the third resistor R3, the second end of the third resistor R3 is connected to the common ground terminal VSS, the output end of the second operational amplifier 82 is connected to the gate of the NMOS transistor NM1, the source of the NMOS transistor NM1 is connected to the first end of the third resistor R3 and the negative input end of the second operational amplifier 82, and the drain of the NMOS transistor NM1 outputs a current ICTAT. Since the operation principle of the bandgap reference voltage source 8 is a common technical means in the art, it is not described herein again.
Output voltage V of band-gap reference voltage source 8REFThe expression of (a) is as follows:
ΔVBE＝VTln (N)
wherein, VREFIs the output voltage of the voltage output terminal VREF, i.e. the output voltage of the bandgap reference voltage source 8, VBEIs the emitter voltage, Δ V, of the third transistor Q3BEFor negative temperature coefficient characteristics, R1Is the resistance value of the first resistor R12Is the resistance value, V, of the second resistor R2TThe thermal voltage has positive temperature coefficient characteristic, N is the ratio of the number of the first transistor Q1 to the number of the second transistor Q2, VPTATThe input signal voltage provided to the analog-to-digital converter is a bandgap reference voltage source. In the above expression, the superposition of the negative temperature coefficient and the positive temperature coefficient characteristic voltage is used to generate the output voltage V with the approximate zero temperature coefficientREF。
The voltage V of the band gap reference voltage source is measuredPTATAs input signal to the analog-to-digital converter, voltage VPTATProportional to absolute temperature. The output voltage V of the voltage output terminal is measuredREFAs a reference voltage of the analog-to-digital converter, the output voltage VREFNear zero temperature coefficient characteristics. The expression of the quantization result of the analog-to-digital converter is:
therefore, a quantized output value mu is obtained, and the quantized output value mu is in direct proportion to the temperature, so that the temperature detection function of the temperature sensor is realized.
The expression pair of the output voltage of the band gap reference voltage source 8 according to the above
And (3) performing deformation processing, wherein the expression after deformation is as follows:
make it
The numerator and denominator of the fraction on the right side of the expression are both divided by R3，R3For the resistance value corresponding to the third resistor R3, an expression is obtained:
let R3＝R2To obtain
Then, according to ohm's law, it can be obtained
Wherein, IPTATThe first temperature current generated by the bandgap reference voltage source 8, i.e. the current output by the drain of the fourth PMOS transistor PM4, is used as the first input current of the analog-to-digital converter; i isCTATThe second temperature current generated by the bandgap reference voltage source 8, i.e. the current output from the drain of the NMOS transistor NM1, is used as the second input current of the analog-to-digital converter.
Will be provided with
Substitution into
Obtaining an expression:
can see, it is right
Converting the relation between the quantized output value and the voltage into the relation between the quantized output value and the current, i.e. converting the input of the analog-to-digital converter fromConverting the voltage signal into a current signal to obtain an expression of the quantized output value of the current-mode temperature sensor
Referring to fig. 1, the operating principle of the temperature sensor of the present invention is as follows:
(1) when the temperature sensor is in the temperature detection mode, the self-detection switch 22 is turned off, the first control switch 31 is turned on, and the second control switch 32 is turned off, the first current source 30 outputs a first temperature current to the integrator 4, and the current value of the first temperature current is IPTAT(ii) a When the first control switch 31 is turned off and the second control switch 32 is turned on, the second current source 33 outputs a second temperature current to the integrator 4, and the current value of the second temperature current is ICTAT；
It can be said that the first temperature current IPTATAnd a second temperature current ICTATMay be provided by the bandgap reference voltage source described above.
After receiving the first temperature current and the second temperature current, the integrator 4 performs an integration operation on the first temperature current and the second temperature current to obtain an integration voltage, and outputs the integration voltage to the comparator 50;
the comparator 50 performs comparison operation on the integrated voltage and a preset reference voltage, and the comparator 50 outputs a logic value "1" or "0" to the filter 6 according to the comparison operation result;
the filter 6 counts the number of the logical values "1" in a preset time period, calculates the ratio of the number of the logical values "1" in all the logical values received by the filter 6 in the time region, and outputs the digital word code according to the ratio of the number of the logical values "1". The output digital word is the first quantized output value, the first quantized output value and the first temperature current IPTATAnd a second temperature current ICTATAre all correlated, the first quantized output value is proportional to the detected temperature. In the temperature detection mode, the expression of the first quantized output value μ of the temperature sensor is
It can be noted that, since the output terminal of the comparator 50 is further connected to the first control switch 31 and the second control switch 32 through the feedback module 7, when the comparator 50 outputs the logic value "1" or "0" to the filter 6, the comparator 50 further feeds back the logic value "1" or "0" to the first control switch 31 and the second control switch 32 to control the on/off of the first control switch 31 and the second control switch 32.
Specifically, when the comparator 50 outputs the logic value "1", the logic value "1" is transmitted to the second control switch 32 through the first feedback signal line 51, and after the second control switch 32 receives the logic value "1", the second control switch 32 is turned on; after the logic value "1" on the first feedback signal line 51 is input into the inverter 53, the inverter 53 outputs the logic value "0", and transmits the logic value "0" to the first control switch 31 through the second feedback signal line 52, and after the first control switch 31 receives the logic value "0", the first control switch 31 is turned off;
when the comparator 50 outputs the logic value "0", the second control switch 32 is turned off after the second control switch 32 receives the logic value "0"; the first control switch 31 receives the logic value "1" output from the inverter 53, and the first control switch 31 is closed and turned on.
It is supplementary that in the temperature detection mode or the self-detection mode, the switching states of the first control switch 31 and the second control switch 32 of the current-type temperature sensor are always opposite, that is, when the first control switch 31 is closed, the second control switch 32 is opened; when the first control switch 31 is open, the second control switch 32 is closed.
(2) The self-detection unit 2 is configured to detect whether the current-mode temperature sensor circuit can normally operate, and assume that the current ambient temperature is an unknown temperature in the self-detection mode, that is, in the self-detection mode, the output of the current-mode temperature sensor capable of normally detecting the temperature should not be affected by the temperature factor, so that the quantized output value output by the current-mode temperature sensor must be a predetermined value unrelated to the temperature, and is used to determine that the current-mode temperature sensor is not failed.
The self-checking working principle of the temperature sensor is as follows:
when the temperature sensor is in the self-checking mode, the self-checking switch 22 is closed, so that the first self-checking current source 20 and the second self-checking current source 21 are connected to a current type temperature sensor circuit, and the temperature sensor enters the self-checking mode;
the self-test switch 22 is closed, and the first self-test current source 20 outputs a first self-test current to the integrator 4, the current value of the first self-test current is
The second self-test current source 21 outputs a second self-test current having a current value of
When the first control switch 31 is closed and the second control switch 32 is open, the first current source 30 outputs a first temperature current to the integrator 4, and the current value of the first temperature current is IPTAT(ii) a When the first control switch 31 is turned off and the second control switch 32 is turned on, the second current source 33 outputs a second temperature current to the integrator 4, and the current value of the second temperature current is ICTAT；
After receiving the first temperature current, the second temperature current, the first self-checking current and the second self-checking current, the integrator 4 performs an integration operation on the first temperature current, the second temperature current, the first self-checking current and the second self-checking current to obtain an integration voltage, and outputs the integration voltage to the comparator 50;
the comparator 50 performs a comparison operation on the integrated voltage and a preset reference voltage, and the comparator 50 outputs a logic value "1" or "0" to the filter 6 according to the comparison operation result. The filter 6 counts the number of the logical values "1" in a preset time period, calculates the ratio of the number of the logical values "1" in all the logical values received by the filter 6 in the time region, and outputs the digital word code according to the ratio. The output digital word is the quantized output value.
In the self-test mode of the temperature sensor, the expression of the second quantized output value mu' of the temperature sensor is
Where N is a real number other than 0 and 1.
Simplifying the expression to obtain
As can be seen from the above expression of the second quantized output value, when the temperature sensor is active, the second quantized output value μ' is expressed
With a first temperature current IPTATAnd a second temperature current ICTATAll the signals are irrelevant, so that a fixed second quantized output value irrelevant to the temperature is obtained, and the self-detection function of the temperature sensor is realized.
It will be appreciated by those skilled in the art that the embodiments described herein are provided to assist the reader in understanding the principles of the invention. Numerous and varied other modifications and combinations can be devised by those skilled in the art based on the teachings herein without departing from the spirit and scope of the invention.
It can be stated that any output current value I based on a positive and negative temperature current source, e.g. with a positive temperature current sourcePTATOutput current value I of negative temperature current sourceCTATThe current type temperature sensor for inputting signals can be matched with the design of the invention to realize the function of self-detection. Including without limitation ramp type temperature sensors or high order multi-bit quantized Delta Sigma modulators, etc.
The invention also provides temperature measuring equipment comprising the temperature sensor.
The temperature measuring equipment has the advantages that:
the temperature sensor is arranged on the temperature measuring equipment, the structure is simple, the temperature current in the quantized output value output by the current type temperature sensor is eliminated through the current output by the self-checking current source, so that the current type temperature sensor outputs a quantized output value irrelevant to the temperature current, the purpose of self-detection of the temperature sensor is achieved, the self-detection of the temperature type sensor is completed, and the self-detection function of the temperature sensor is realized.
The temperature sensor and the temperature measuring equipment provided by the invention can be used for detecting whether the temperature sensor circuit is invalid or not, and can be used in application scenes with high reliability requirements, such as military industry, vehicle-mounted scenes and the like.
Although the embodiments of the present invention have been described in detail hereinabove, it is apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it is to be understood that such modifications and variations are within the scope and spirit of the present invention as set forth in the following claims. Moreover, the invention as described herein is capable of other embodiments and of being practiced or of being carried out in various ways.
Claims (10)
1. The temperature sensor is characterized by comprising a self-detection unit, a current source unit and an analog-to-digital conversion unit, wherein the current source unit is connected with the analog-to-digital conversion unit;
the analog-to-digital conversion unit comprises an integrator, a quantizer and a filter, wherein the output end of the current source unit is connected with the input end of the integrator, the output end of the integrator is connected with the input end of the quantizer, and the output end of the quantizer is connected with the input end of the filter;
the self-checking unit with the current source unit is connected through the self-checking switch, the self-checking unit includes first self-checking current source and second self-checking current source, the positive pole of first self-checking current source is connected the negative pole of second self-checking current source, the anodal ground connection of second self-checking current source, first self-checking current source with second self-checking current source is used for making analog-to-digital conversion unit output second quantization output value, second quantization output value is used for detecting whether temperature sensor is inefficacy.
2. The temperature sensor according to claim 1, wherein the current source unit comprises a first current source, a first control switch, a second control switch and a second current source, wherein an anode of the first current source is connected to a cathode of the first control switch, the second control switch and a cathode of the second current source in sequence, an anode of the second current source is grounded, and a node between the first control switch and the second control switch is connected to an input terminal of the integrator.
3. The temperature sensor according to claim 2, wherein the node between the first control switch and the second control switch is further connected to one end of the self-test switch, and the other end of the self-test switch is connected to the node between the first self-test current source and the second self-test current source.
4. The temperature sensor according to claim 2, wherein the temperature sensor enters a temperature detection mode when the self-test switch is turned off;
after the temperature sensor enters a temperature detection mode, the first current source outputs a first temperature current and the second current source outputs a second temperature current to the analog-to-digital conversion unit;
the analog-to-digital conversion unit receives the first temperature current and the second temperature current, and then quantizes the first temperature current and the second temperature current to obtain a first quantized output value, wherein the first quantized output value is related to both the first temperature current and the second temperature current.
5. The temperature sensor of claim 4, wherein when the self-test switch is closed, the temperature sensor enters a self-test mode;
after the temperature sensor enters a self-test mode, the first self-test current source outputs the first self-test current, the second self-test current source outputs the second self-test current, the first current source outputs a first temperature current, and the second current source outputs a second temperature current to the analog-to-digital conversion unit;
after receiving the first self-detection current, the second self-detection current, the first temperature current and the second temperature current, the analog-to-digital conversion unit performs quantization processing on the first self-detection current, the second self-detection current, the first temperature current and the second temperature current to obtain a second quantized output value;
when the second quantized output value is not related to the first temperature current or the second temperature current, judging that the temperature sensor is effective;
determining that the temperature sensor is disabled when the second quantized output value is related to either of the first temperature current and the second temperature current.
6. The temperature sensor of claim 5, wherein the first self-test current is of the second temperature current
The second self-checking current is the first temperature current
Multiple, N is a real number other than 0 and 1.
7. The temperature sensor according to claim 2, wherein the quantizer includes a comparator, a first feedback signal line, a second feedback signal line, and an inverter, an output terminal of the comparator being connected to the second control switch through the first feedback signal line, a node on the first feedback signal line being connected to an input terminal of the inverter, an output terminal of the inverter being connected to the first control switch through the second feedback signal line;
and the comparator outputs a result and feeds the result back to the second control switch and the first control switch so as to respectively control the second control switch and the first control switch.
8. The temperature sensor according to claim 7, wherein the integrator comprises an operational amplifier, a capacitor and a reset switch, a negative input terminal of the operational amplifier is connected to a node between the first control switch and the second control switch, a positive input terminal of the operational amplifier is connected to a positive input terminal of the comparator, and an output terminal of the operational amplifier is connected to a negative input terminal of the comparator;
the two ends of the reset switch are respectively connected with the negative input end of the operational amplifier and the output end of the operational amplifier, and the capacitor is connected with the reset switch in parallel.
9. The temperature sensor of claim 8, wherein the integrator further comprises a voltage source having a positive terminal connected to the positive input of the operational amplifier and the positive input of the comparator, and a negative terminal connected to ground.
10. A thermometric apparatus comprising a temperature sensor according to any one of claims 1 to 9.
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