By the temperature measuring circuit of translation conversion reference level to proofread and correct
Technical field
The present invention system relates to a kind of temperature measuring circuit, relates in particular to the temperature measuring circuit that a kind of conversion reference level by translation analog to digital change-over circuit is realized error correcting function.
Background technology
Because the semiconductor pn of diode assembly meets the base stage of face or transistor component and the semiconductor pn between emitter-base bandgap grading and connects be relative to each other connection and be the function of temperature of potential difference (PD) that the face two ends are presented and therebetween the electric current of flowing through, and comes detected temperatures so extensively utilize this semiconductor pn to connect face in technical field of integrated circuits.Fig. 1 has shown the circuit composition synoptic diagram of existing temperature measuring circuit 10.Typically, temperature measuring circuit 10 is provided to monitor the temperature of ambient systems 20.For example, ambient systems 20 is a computing machine, electronic installation or specific circuit region, and wherein being provided with to provide semiconductor pn to connect the thermal sensor 21 of face with detected temperatures.As shown in the figure, thermal sensor 21 is implemented by a pnp two-carrier transistor, and the semiconductor pn between its base stage and emitter-base bandgap grading connects face in order to detected temperatures.
In temperature measuring circuit 10, the switch S of current source circuit 11
1With S
2By control circuit 12 decision conductings and not conducting, so that allow different electric current I respectively
1With I
2Be applied to thermal sensor 21.Suppose electric current I
1Being applied to base stage and the potential difference (PD) between emitter-base bandgap grading that thermal sensor 21 caused is V
BE1And electric current I
2Being applied to base stage and the potential difference (PD) between emitter-base bandgap grading that thermal sensor 21 caused is V
BE2, then counting circuit 13 makes potential difference (PD) V
BE1With V
BE2Can obtain following equation (1) after subtracting each other each other:
Wherein K is that Bo Ziman (Boltzmann) constant, T are that absolute temperature, q are elementary charge, R
eSeries connection dead resistance, R for emitter-base bandgap grading
bFor the series connection dead resistance and the β of base stage is transistorized gain coefficient (gain).Therefore, the potential difference (PD) Δ V that produced of counting circuit 13
BEBut be one to vary with temperature and the simulating signal of representation temperature.Subsequently, (analog-to-digital converter ADC) 14 makes this analog temperature conversion of signals become a digital temperature signal to the analog to digital change-over circuit.
From equation (1) as can be known, the series connection dead resistance R of thermal sensor 21
eWith R
bCause a temperature independent constant term, that is (I
1-I
2) (R
e+ R
b/ β).In order to eliminate this kind series connection dead resistance R
eWith R
bThe error that is caused, prior art are used three kinds or more kinds of different electric current usually, excite identical thermal sensor 21 in regular turn, realize temperature measurement result accurately with expectation.Yet, use the existing mode of excitation of three kinds or more kinds of different electric current not only to cause operating frequency to increase rapidly but also more cause unnecessary energy consumption and temperature change.Even keep under the fixing condition at operating frequency, the mode of excitation in regular turn of more kinds of different electric currents will prolong each required time of temperature survey circulation inevitably, thereby reduce the reaction velocity of temperature measuring circuit 10.
On the other hand, what temperature measuring circuit 10 was in fact measured is the temperature that is formed with the semiconductor substrate of thermal sensor 21 on it, and this measurement result may be also inequality with the authentic representative of ambient systems 20 degree warm in nature.For example, when ambient systems 20 is a computing machine, the temperature of the heat sink of normally measuring ambient systems 20 22 that people are interested in, but not be provided with the temperature of the semiconductor substrate of thermal sensor 21.In this case, the manufacturer of ambient systems 20 provides the temperature contrast data Δ that exists between the substrate of relevant heat sink 22 and thermal sensor 21 T, so that existing temperature measuring circuit 10 is stored in it in buffer 15.Subsequently, adding circuit 16 is with the numeral output of analog to digital change-over circuit 14 and the temperature contrast data Δ T addition each other in the buffer 15, so that produce a final temperature signal Tmp.
Summary of the invention
Because foregoing problems the object of the present invention is to provide a kind of temperature measuring circuit, realize error correcting function by the conversion reference level of translation analog to digital change-over circuit.
According to an aspect of of the present present invention, a kind of temperature measuring circuit is provided, have an electric current energizing circuit, a counting circuit, a correction value generating circuit and an analog to digital change-over circuit.The electric current energizing circuit applies at least two electric current to thermal sensors in regular turn, makes this thermal sensor produce at least two output signals accordingly.In response to these at least two output signals, counting circuit calculates an analog temperature signal, and it represents the detected temperature of this thermal sensor.Correction value generating circuit produces a corrected value.The analog to digital change-over circuit becomes a digital temperature signal according to a conversion reference level with this analog temperature conversion of signals.The translation adjustment of this conversion reference level according to this corrected value.
This thermal sensor has semiconductor pn and connects face, makes these at least two electric currents to flow through in regular turn this semiconductor pn connects face and produce at least two potential difference (PD) thereon respectively, as these at least two output signals.This corrected value is to apply at least three electric currents to this thermal sensor in regular turn by this electric current energizing circuit to calculate, and makes this corrected value in order to revise a constant term error of this analog temperature signal.This thermal sensor system is arranged in the substrate of an ambient systems.This corrected value is provided by this ambient systems, with the difference between the representative temperature of revising detected this temperature of this thermal sensor and this ambient systems.
According to another aspect of the present invention, a kind of thermometry is provided, have the following step.At first, apply at least two electric current to thermal sensors in regular turn, make this thermal sensor produce at least two output signals accordingly.Calculate an analog temperature signal in response to these at least two output signals, it represents the detected temperature of this thermal sensor.Produce a corrected value.According to a conversion reference level this analog temperature conversion of signals is become a digital temperature signal.The translation adjustment of this conversion reference level according to this corrected value.
According to another aspect of the present invention, provide a kind of electric current energizing circuit, in order to excite a thermal sensor.This electric current energizing circuit has a measuring current source circuit, a correcting current source circuit, a correction control circuit and a circuit of measurement and control.The measuring current source circuit provides one first to measure electric current and one second measurement electric current.The correcting current source circuit provides a correcting current.Correction control circuit allows this first measurement electric current, this second measurement electric current, is applied to this thermal sensor in regular turn with this correcting current, in order to measure the constant term error relevant for this thermal sensor.Circuit of measurement and control allows this first measurement electric current and this second measurement electric current to be applied to this thermal sensor in regular turn, in order to measure a temperature of this thermal sensor.This correction control circuit is activated to carry out the measurement of this constant term error than this circuit of measurement and control is more Zao.
Description of drawings
Fig. 1 has shown the circuit composition synoptic diagram of existing temperature measuring circuit;
Fig. 2 has shown the circuit composition synoptic diagram according to temperature measuring circuit of the present invention;
Fig. 3 (A) has shown the mode of operation figure of foundation counting circuit of the present invention to 3 (C);
Fig. 4 has shown the principle of operation synoptic diagram according to translation correction type analog to digital change-over circuit of the present invention; And
Fig. 5 shows according to the detailed circuit diagram of example of analog to digital change-over circuit of the present invention.
The primary clustering symbol description
10, temperature measuring circuit 11, current source circuit
12, control circuit 13, counting circuit
14, analog to digital change-over circuit (ADC) 15, buffer
16, adding circuit 20, ambient systems
21, thermal sensor 22, heat sink
30, temperature measuring circuit 31, measuring current source circuit
32, correcting current source circuit 33, circuit of measurement and control
34, correction control circuit 35, counting circuit
36, correction value generating circuit
37, translation correction type analog to digital change-over circuit (ADC)
41, multiplier 42, totalizer
43, proofread and correct buffer 51, sampling/modulation circuit
52, clock pulse generator 53, counter
54, frequency eliminator 55, output state
AM, differential amplifier C
a~C
d, electric capacity
CF, corrected value CLK, clock signal
I
1, I
2, measure electric current I
3, correcting current
R
b, R
e, series connection dead resistance RST, reset signal
S
1, S
2, S
3, S
a~S
d, switch Tmp, temperature measurement result
V
BE, the potential difference (PD) d Δ V between base stage and emitter-base bandgap grading
BE, the constant term error
Δ T, temperature contrast data
Embodiment
Explanation hereinafter and accompanying drawing will make aforementioned and other purpose of the present invention, feature, more obvious with advantage.Now describe in detail according to preferred embodiment of the present invention with reference to the accompanying drawings.
Fig. 2 has shown the circuit composition synoptic diagram according to temperature measuring circuit 30 of the present invention.In temperature measuring circuit 30, a kind of electric current energizing circuit is made of jointly a measuring current source circuit 31, a correcting current source circuit 32, a circuit of measurement and control 33 and 34 of correction control circuits.Measuring current source circuit 31 has first and second and measures electric current I
1With I
2, respectively via switch S
1With S
2And be supplied to the emitter-base bandgap grading of thermal sensor 21.Correcting current source circuit 32 has a correcting current I
3, via switch S
3And be supplied to the emitter-base bandgap grading of thermal sensor 21.Before temperature measuring circuit 30 began to measure the temperature of thermal sensor 21, correction control circuit 34 must be activated earlier and measure electric current I to control first and second
1With I
2And correcting current I
3Be applied to thermal sensor 21 in regular turn.Suppose electric current I
1, I
2, and I
3Base stage that is caused for thermal sensor 21 and the potential difference (PD) between emitter-base bandgap grading are respectively V
BE1, V
BE2, and V
BE3, then counting circuit 35 can calculate shown in an equation (2) descends:
Suppose electric current I now again
1, I
2, and I
3Between satisfy following ratio condition (3):
I
1∶I
2∶I
3=A
2∶A∶1 (3)
Promptly first measure electric current I
1It is the second measurement electric current I
2A doubly, and second measure electric current I
2Be correcting current I
3A doubly, wherein A is greater than zero, then equation (2) can further be simplified to equation as follows (4):
Therefore, by correcting current I
3Help, counting circuit 35 can detect effectively by series connection dead resistance R
eWith R
bThe constant term error d Δ V that is caused
BESubsequently, this constant term error d Δ V
BEBe sent to correction value generating circuit 36 in order to produce corrected value CF.In a preferred embodiment, this corrected value CF must measure appropriately before any temperature survey circulation beginning in advance, used so that follow-up all temperature survey round-robin error corrections to be provided.
Fig. 3 (A) shows that to 3 (C) foundation counting circuit 35 of the present invention is detecting constant term error d Δ V
BEThe time mode of operation figure.In Fig. 3 (A), switch S
aConducting, switch S
bConducting, switch S
cMake capacitor C
cBe coupled to non-inverting input (+) and the switch S of differential amplifier A M
dMake capacitor C
dBe coupled to the inverting input (-) of differential amplifier A M.In addition, switch S
1Conducting and switch S
2With S
3Not conductings, thereby only allow first to measure electric current I
1Be applied to thermal sensor 21 and produce the first potential difference (PD) V between base stage and emitter-base bandgap grading
BE1In this phase one, because the voltage that the non-inverting input (+) of differential amplifier A M and inverting input (-) are located all is zero, so the output voltage V of differential amplifier A M
Out (1)Be zero.In Fig. 3 (B), switch S
aWith S
bAll become not conducting.In addition, switch S
2Conducting and switch S
1With S
3Not conductings, thereby only allow second to measure electric current I
2Be applied to thermal sensor 21 and produce the second potential difference (PD) V between base stage and emitter-base bandgap grading
BE2In this subordinate phase, because the voltage that the non-inverting input (+) of differential amplifier A M and inverting input (-) are located all is (V
BE1-V
BE2So)/2 are the output voltage V of differential amplifier A M
Out (2)Be (V
BE1-V
BE2).In Fig. 3 (C), switch S
cBecome and make capacitor C
cBe coupled to the inverting input (-) of differential amplifier A M, and switch S
dBecome and make capacitor C
dBe coupled to the non-inverting input (+) of differential amplifier A M.In addition, switch S
3Conducting and switch S
1With S
2Not conductings, thereby only allow correcting current I
3Be applied to thermal sensor 21 and produce the 3rd potential difference (PD) V between base stage and emitter-base bandgap grading
BE3In this phase III, the output voltage V of differential amplifier A M
Out (3)Become (V
BE1-V
BE2)-(V
BE2-V
BE3), i.e. the equation (2) of institute's desire detection and the constant term error d Δ V of (4)
BE
Please note according to correcting current source circuit among the present invention 32 and correction control circuit 34 and finish aforesaid constant term error d Δ V
BEThe detection measuring program and export correction value generating circuit 36 to after, i.e. shut-down operation.In other words, carrying out the temperature survey circulation time, temperature measuring circuit 30 only uses circuit of measurement and control 33 control survey current source circuits 31 to apply first and second in regular turn and measures electric current I
1With I
2To thermal sensor 21.Therefore, the mode of operation of counting circuit 35 in the temperature survey circulation only is confined to Fig. 3 (A) and 3 (B).Satisfy ratio condition (3) and recording the constant term error d Δ V of equation (4)
BESituation under, base stage that counting circuit 35 is obtained and the potential difference (PD) Δ V between emitter-base bandgap grading
BECan be expressed as follows:
Therefore, in the present invention, utilize first and second to measure electric current I
1With I
2The potential difference (PD) Δ V that is obtained
BEAs long as adjusted a constant term error d Δ V by translation
BEWith the product of scale factor A/ (A-1), can produce correct temperature measurement result.Because this constant term error d Δ V
BEIn advance via correcting current I
3Assistance and detect and be stored in correction value generating circuit 36, so need not in each temperature survey circulation, to detect again repeatedly again.
Except constant term error d Δ V
BEOutside, the temperature contrast data Δ T of 22 of the relevant thermal sensor 21 that provided by ambient systems 20 and heat sinks also can be provided correction value generating circuit 36.Because constant term error d Δ V
BEBut all belong to the error that translation is proofreaied and correct with temperature contrast data Δ T, so correction value generating circuit 36 can be integrated into it single corrected value CF.Based on this corrected value CF, the suitable conversion reference level of translation correction type analog to digital change-over circuit 37 decisions.Fig. 4 shows the principle of operation synoptic diagram according to translation correction type analog to digital change-over circuit 37 of the present invention.Broadly, analog to digital change-over circuit 37 is taken a sample for the simulating signal Alg that is received according to a predetermined sampling frequency.Subsequently, take a sample and analog result on mathematical concept, can be considered via digital respective shaft Dx and convert a digital signal to, wherein the actual value of this digital signal depends on the relative position of conversion reference level REF.For example, as shown in Figure 4, original conversion reference level REF translation downwards behind the one corrected value CF and form conversion reference level REF_S after the translation.For original conversion reference level REF, analog sample AS converts digital signal Dgtl to.Have only for the conversion reference level REF_S after the translation, analog sample AS converts digital signal Dgt2 to.Therefore, by the mode of translation conversion reference level REF, translation correction type analog to digital change-over circuit 37 can carry out constant term error d Δ V effectively in the transfer process of analog to digital
BEObtain a correct temperature measurement result with the correction of temperature contrast data Δ T, need not additionally to practise existing additive operation program.
Fig. 5 shows the detailed circuit diagram according to the example of analog to digital change-over circuit 37 of the present invention.Sampling/modulation circuit 51 is according to clock signal CLK that clock pulse generator 52 provided and for from counting circuit 35 and base stage of coming and the potential difference (PD) Δ V between emitter-base bandgap grading
BETake a sample, and the sampling result modulation is become a pulse sequence signal.For example, sampling/modulation circuit 51 must be implemented by a Delta-Sigma analog to digital modulator, thereby this pulse sequence signal is the pairing digital signal of analog sample.The pulse sequence signal that comes from sampling/modulation circuit 51 is applied to counter 53.In a cycle of being scheduled to, the pulse number that counter 53 is counted in the received pulse sequence signal.Because the counting mode of counter 53 is upwards to increase progressively counting since a counting reference value, so translation adjusts that effect of this counting reference value is equal to promptly that translation adjusts that counter 53 calculates count results, so the inventor is applied to this know-why in the constant term error correction of temperature measurement result.
Particularly, the counting reference value of counter 53 is determined by the corrected value CF that correction value generating circuit 36 is provided.In correction value generating circuit 36, the constant term error d Δ V that comes from counting circuit 35
BEBe multiplied by scale factor A/ (A-1) via multiplier 41, and subsequently via totalizer 42 with the temperature contrast data Δ T addition that comes from ambient systems 20, with synthetic desired single corrected value CF and be stored in and proofread and correct in the buffer 43.In other words, the embodiment shown in Figure 5 counting reference value of adjusting counter 53 by translation realizes the purpose of the translation conversion reference level REF of Fig. 4.On the other hand, frequency eliminator 54 is the clock signal CLK frequency elimination of clock pulse generator 52, resets signal RST with what produce a lower frequency.In one embodiment, the frequency of reseting signal RST that produced of frequency eliminator 54 gets the frequency of the clock signal CLK of clock pulse generator 52 divided by 1024.Therefore, through 1024 all after dates, counter 53 can be reset gets back to the counting reference value at clock signal CLK, so that restart counting.Similarly, this counting reference value is determined by the corrected value CF that correction value generating circuit 36 is provided.In addition, counter 53 in 1024 cycles of clock signal CLK, count and the result be sent to output state 55, export the external world to as temperature measurement result Tmp.This temperature measurement result Tmp also upgrades according to reseting the frequency of signal RST.
Though the present invention is illustrated as illustration by means of preferred embodiment, should understand: the invention is not restricted to this disclosed embodiments.On the contrary, this invention is intended to contain tangible for those of ordinary skills various modifications and similar configuration.Therefore, the scope of claim should be according to the widest annotation, and this type of is revised and similar configuration to contain all.