CN100445712C - Temperature measurement circuit with correction by translating a switching reference level - Google Patents

Abstract

The invention discloses a temperature measuring circuit which is provided with a current excitation circuit, a calculation circuit, a correction value generation circuit and an analog-to-digital conversion circuit. The current excitation circuit sequentially applies at least two currents to a thermal sensor, so that the thermal sensor correspondingly generates at least two output signals. In response to the at least two output signals, the computing circuit calculates an analog temperature signal representative of the temperature sensed by the thermal sensor. The analog-to-digital conversion circuit converts the analog temperature signal into a digital temperature signal according to a conversion reference level. The conversion reference level is adjusted in a translation mode according to a correction value generated by the correction value generation circuit.

Description

Temperature measurement circuit for correction by shifting the reference level

technical field

The invention relates to a temperature measurement circuit, in particular to a temperature measurement circuit which realizes error correction function by shifting the conversion reference level of the analog to digital conversion circuit.

Background technique

Since the potential difference between the semiconductor pn junction of the diode component or the semiconductor pn junction between the base and the emitter of the transistor component and the current flowing through it are related to each other and are a function of temperature, in integrated circuit technology This semiconductor pn junction is widely used in the field to detect temperature. FIG. 1 shows a schematic circuit diagram of a conventional temperature measurement circuit 10 . Typically, the temperature measurement circuit 10 is configured to monitor the temperature of an external system 20 . For example, the external system 20 is a computer, an electronic device, or a specific circuit area, in which a thermal sensor 21 that can provide a semiconductor pn junction to detect temperature is provided. As shown in the figure, the thermal sensor 21 is implemented by a pnp bipolar transistor, and the semiconductor pn junction between its base and emitter is used to detect temperature.

In the temperature measurement circuit 10 , the switches S ₁ and S ₂ of the current source circuit 11 are turned on or off by the control circuit 12 to allow different currents I ₁ and I ₂ to be applied to the thermal sensor 21 respectively. Assuming that the potential difference between the base and the emitter caused by the current I ₁ applied to the thermal sensor 21 is V _BE1 and the potential difference between the base and the emitter caused by the current I ₂ applied to the thermal sensor 21 is V _BE2 , then The calculation circuit 13 subtracts the potential differences V _BE1 and V _BE2 from each other to obtain the following equation (1):

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">BE</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; KT</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

where K is the Boltzmann constant, T is the absolute temperature, q is the elementary charge, R _e is the series parasitic resistance of the emitter, R _b is the series parasitic resistance of the base, and β is the gain coefficient of the transistor (gain ). Therefore, the potential difference ΔV _BE generated by the calculation circuit 13 is an analog signal that can represent temperature as it changes with temperature. Then, an analog-to-digital converter (analog-to-digital converter, ADC) 14 converts the analog temperature signal into a digital temperature signal.

It can be known from equation (1) that the series parasitic resistances Re _and R _b of the thermal sensor 21 cause a constant term independent of temperature, ie (I ₁ −I ₂ )( _Re +R _b /β). In order to eliminate the error caused by the series parasitic resistances Re _and R _b , the prior art generally uses three or more different currents to sequentially excite the same thermal sensor 21 in order to achieve accurate temperature measurement results. However, the existing excitation method using three or more different currents not only causes a rapid increase in operating frequency but also causes unnecessary power consumption and temperature variation. Even under the condition that the operating frequency is kept constant, more sequential excitation of different currents will inevitably prolong the time required for each temperature measurement cycle, thereby reducing the response speed of the temperature measurement circuit 10 .

On the other hand, what the temperature measurement circuit 10 actually measures is the temperature of the semiconductor substrate on which the thermal sensor 21 is formed, and the measurement result may be different from the true representative temperature of the external system 20 . For example, when the external system 20 is a computer, people are usually interested in measuring the temperature of the cooling plate 22 of the external system 20 rather than the temperature of the semiconductor substrate on which the thermal sensor 21 is disposed. In this case, the manufacturer of the external system 20 provides the temperature difference data ΔT between the cooling plate 22 and the substrate of the thermal sensor 21 so that the existing temperature measurement circuit 10 can store it in a register 15 . Subsequently, the adding circuit 16 adds the digital output of the analog-to-digital converting circuit 14 and the temperature difference data ΔT in the register 15 to each other to generate a final temperature signal Tmp.

Contents of the invention

In view of the aforementioned problems, the object of the present invention is to provide a temperature measurement circuit, which realizes the error correction function by shifting the conversion reference level of the analog-to-digital conversion circuit.

According to one aspect of the present invention, a temperature measurement circuit is provided, which has a current excitation circuit, a calculation circuit, a correction value generation circuit, and an analog-to-digital conversion circuit. The current excitation circuit sequentially applies at least two currents to a thermal sensor, so that the thermal sensor generates at least two output signals correspondingly. In response to the at least two output signals, the calculation circuit calculates an analog temperature signal representing a temperature detected by the thermal sensor. The correction value generating circuit generates a correction value. The analog-to-digital conversion circuit converts the analog temperature signal into a digital temperature signal according to a conversion reference level. The conversion reference level is shifted and adjusted according to the calibration value.

The thermal sensor has a semiconductor pn junction, so that the at least two currents flow through the semiconductor pn junction in sequence to generate at least two potential differences thereon as the at least two output signals. The correction value is calculated by sequentially applying at least three currents to the thermal sensor through the current excitation circuit, so that the correction value is used to correct a constant term error of the analog temperature signal. The thermal sensor is disposed in a substrate of an external system. The correction value is provided by the external system to correct a difference between the temperature detected by the thermal sensor and a representative temperature of the external system.

According to another aspect of the present invention, a method for measuring temperature is provided, comprising the following steps. Firstly, at least two currents are sequentially applied to a thermal sensor, so that the thermal sensor generates at least two output signals correspondingly. An analog temperature signal representing a temperature detected by the thermal sensor is calculated in response to the at least two output signals. Generate a calibration value. The analog temperature signal is converted into a digital temperature signal according to a conversion reference level. The conversion reference level is shifted and adjusted according to the correction value.

According to another aspect of the present invention, a current excitation circuit for exciting a thermal sensor is provided. The current excitation circuit has a measurement current source circuit, a correction current source circuit, a correction control circuit, and a measurement control circuit. The measurement current source circuit provides a first measurement current and a second measurement current. The correction current source circuit provides a correction current. The calibration control circuit allows the first measurement current, the second measurement current, and the calibration current to be sequentially applied to the thermal sensor for measuring a constant-term error related to the thermal sensor. The measurement control circuit allows the first measurement current and the second measurement current to be sequentially applied to the thermal sensor for measuring a temperature of the thermal sensor. The correction control circuit is activated earlier than the measurement control circuit for the measurement of the constant term error.

Description of drawings

Fig. 1 has shown the circuit composition schematic diagram of existing temperature measurement circuit;

Fig. 2 has shown the circuit composition schematic diagram according to the temperature measurement circuit of the present invention;

Fig. 3 (A) to 3 (C) has shown the operating state chart according to the computing circuit of the present invention;

4 shows a schematic diagram of the operation principle of the translation correction type analog-to-digital conversion circuit according to the present invention; and

FIG. 5 shows a detailed circuit diagram of an example of an analog-to-digital conversion circuit according to the present invention.

Explanation of main component symbols

10. Temperature measurement circuit 11. Current source circuit

12. Control circuit 13. Calculation circuit

14. Analog to digital conversion circuit (ADC) 15. Register

16. Addition circuit 20. External system

21. Thermal sensor 22. Heat sink

30. Temperature measurement circuit 31. Measurement current source circuit

32. Correction current source circuit 33. Measurement control circuit

34. Calibration control circuit 35. Calculation circuit

36. Correction value generating circuit

37. Translation correction type analog to digital conversion circuit (ADC)

41. Multiplier 42. Adder

43. Calibration register 51. Sampling/modulation circuit

52. Clock generator 53. Counter

54. Frequency divider 55. Output register

AM, differential amplifier C _a ~ C _d , capacitance

CF, correction value CLK, clock signal

I ₁ , I ₂ , measuring current I ₃ , correcting current

R _b , Re _e , series parasitic resistance RST, reset signal

S ₁ , S ₂ , S ₃ , S _a ~ S _d , switch Tmp, temperature measurement results

V _BE , potential difference between base and emitter dΔV _BE , constant term error

ΔT, temperature difference data

Detailed ways

The foregoing and other objects, features, and advantages of the present invention will be more apparent from the following description and accompanying drawings. Preferred embodiments according to the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 shows a schematic diagram of the circuit composition of the temperature measurement circuit 30 according to the present invention. In the temperature measurement circuit 30 , a current excitation circuit is composed of a measurement current source circuit 31 , a calibration current source circuit 32 , a measurement control circuit 33 , and a calibration control circuit 34 . The measurement current source circuit 31 has first and second measurement currents I ₁ and I ₂ , which are respectively supplied to the emitter of the thermal sensor 21 via switches S ₁ and S ₂ . The calibration current source circuit 32 has a calibration current I ₃ supplied to the emitter of the thermal sensor 21 via the switch S ₃ . Before the temperature measurement circuit 30 starts to measure the temperature of the thermal sensor 21 , the calibration control circuit 34 must be activated to control the first and second measurement currents I ₁ and I ₂ and the calibration current I ₃ to be sequentially applied to the thermal sensor 21 . Assuming that the potential differences between the base and the emitter caused by the currents I ₁ , I ₂ , and I ₃ for the thermal sensor 21 are V _BE1 , V _BE2 , and V _BE3 , the calculation circuit 35 can calculate an equation (2 ) as shown below:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">V</figure-callout></span><figure-callout\; id="2"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; KT</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="3"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">V</figure-callout></span><figure-callout\; id="3"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; KT</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; )</span>$

$\mathrm{<span\; class="notranslate">\; d\&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; KT</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}}{{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Now assume that the following proportionality condition (3) is satisfied among the currents I ₁ , I ₂ , and I ₃ :

I ₁ : I ₂ : I ₃ = A ² : A : 1 (3)

That is, the first measurement current _I1 is A times the second measurement current _I2 , and the second measurement current _I2 is A times the correction current _I3 , wherein A is greater than zero, then the equation (2) can be further simplified as follows Equation (4) shown:

${\mathrm{<span\; class="notranslate">\; d\&Delta;V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; *</span>{\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}}{\mathrm{<span\; class="notranslate">\; \&beta;</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Therefore, with the help of the correction current I ₃ , the calculating circuit 35 can effectively detect the constant-term error dΔV _BE caused by the series parasitic resistances Re _and R _b . Then, the constant term error dΔV _BE is sent to the correction value generating circuit 36 for generating the correction value CF. In a preferred embodiment, the correction value CF must be pre-determined before any temperature measurement cycle starts, so as to be used for error correction of all subsequent temperature measurement cycles.

3(A) to 3(C) are diagrams showing the operation state of the calculation circuit 35 according to the present invention when detecting the constant term error dΔV _BE . In Figure 3(A), switch S _a is turned on, switch S _b is turned on, switch S _c couples capacitor C _c to the non-inverting input (+) of differential amplifier AM, and switch S _d makes capacitor C _d is coupled to the inverting input (-) of the differential amplifier AM. In addition, the switch S ₁ is turned on and the switches S ₂ and S ₃ are both turned on, so only the first measurement current I ₁ is allowed to be applied to the thermal sensor 21 to generate the first potential difference V _BE1 between the base and the emitter. In this first stage, since the voltages at both the non-inverting (+) and inverting (-) inputs of the differential amplifier AM are zero, the output voltage V _out(1) of the differential amplifier AM is zero. In FIG. 3(B), both switches S _a and S _b become non-conductive. In addition, the switch S ₂ is turned on and the switches S ₁ and S ₃ are both turned on, so only the second measurement current I ₂ is allowed to be applied to the thermal sensor 21 to generate a second potential difference V _BE2 between the base and the emitter. During this second phase, since the voltages at both the non-inverting (+) and inverting (-) inputs of the differential amplifier AM are (V _BE1 -V _BE2 )/2, the differential amplifier AM's The output voltage V _out(2) is (V _BE1 -V _BE2 ). In Figure 3(C), the switch _Sc becomes to couple the capacitor _Cc to the inverting input (-) of the differential amplifier AM, and the switch _Sd becomes to couple the capacitor _Cd to the non-inverting input of the differential amplifier AM. Inverting input (+). In addition, the switch S ₃ is turned on and the switches S ₁ and S ₂ are both turned on, so only the correction current I ₃ is allowed to be applied to the thermal sensor 21 to generate a third potential difference V _BE3 between the base and the emitter. In this third stage, the output voltage V _out(3) of the differential amplifier AM becomes (V _BE1 -V _BE2 )-(V _BE2 -V _BE3 ), that is, the equations (2) and (4) to be detected The constant term error dΔV _BE .

Please note that the correction current source circuit 32 and the correction control circuit 34 in the present invention stop operating after completing the detection procedure of the aforementioned constant term error dΔV _BE and outputting it to the correction value generation circuit 36 . In other words, when performing a temperature measurement cycle, the temperature measurement circuit 30 only uses the measurement control circuit 33 to control the measurement current source circuit 31 to sequentially apply the first and second measurement currents I ₁ and I ₂ to the thermal sensor 21 . Therefore, the operation state of the calculation circuit 35 in the temperature measurement cycle is limited only to FIGS. 3(A) and 3(B). In the case that the proportional condition (3) is satisfied and the error dΔV _BE of the constant term of the equation (4) has been measured, the potential difference ΔV _BE between the base and the emitter obtained by the calculation circuit 35 can be expressed as follows:

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">V</figure-callout></span><figure-callout\; id="2"\; label="V\; BE"\; filenames="C20051011813600161.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; KT</span>}}{\mathrm{<span\; class="notranslate">\; q</span>}}\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}}{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; d\&Delta;</span>}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BE</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

Therefore, according to the present invention, the potential difference ΔV _BE obtained by using the first and second measurement currents I ₁ and I ₂ only needs to be translated and adjusted by the product of a constant term error dΔV _BE and the proportional factor A/(A-1) , to produce correct temperature measurements. Since the constant term error dΔV _BE has been previously detected and stored in the correction value generation circuit 36 with the assistance of the correction current I ₃ , it is not necessary to repeatedly re-detect in each temperature measurement cycle.

In addition to the constant term error dΔV _BE , the correction value generating circuit 36 can also receive the temperature difference data ΔT between the thermal sensor 21 and the cooling plate 22 provided by the external system 20 . Since both the constant term error dΔV _BE and the temperature difference data ΔT are translationally correctable errors, the correction value generating circuit 36 can integrate them into a single correction value CF. Based on this correction value CF, the translation correction type analog-to-digital conversion circuit 37 decides an appropriate conversion reference level. FIG. 4 shows a schematic diagram of the operation principle of the translation correction analog-to-digital conversion circuit 37 according to the present invention. Broadly speaking, the analog-to-digital conversion circuit 37 samples the received analog signal Alg according to a predetermined sampling frequency. Subsequently, the sampled analog result can be regarded as being converted into a digital signal via the digital corresponding axis Dx in a mathematical concept, wherein the actual value of the digital signal depends on the relative position of the conversion reference level REF. For example, as shown in FIG. 4 , the original conversion reference level REF is shifted downward by a correction value CF to form a shifted conversion reference level REF_S. For the original converted reference level REF, the analog samples AS are converted into digital signals Dgtl. Only for the shifted conversion reference level REF_S, the analog samples AS are converted into digital signal Dgt2. Therefore, by translating the reference level REF, the translation correction analog-to-digital conversion circuit 37 can effectively correct the constant term error dΔV _BE and the temperature difference data ΔT during the analog-to-digital conversion process to obtain a correct The temperature measurement result does not require additional learning of the existing addition program.

FIG. 5 shows a detailed circuit diagram of an example of an analog-to-digital conversion circuit 37 according to the present invention. The sampling/modulation circuit 51 samples the potential difference ΔV _BE between the base and the emitter from the calculation circuit 35 according to the clock signal CLK provided by the clock generator 52, and modulates the sampling result into a pulse train signal. For example, the sampling/modulation circuit 51 can be implemented by a Delta-Sigma analog-to-digital modulator, so the pulse train signal is a digital signal corresponding to the analog samples. The pulse train signal from the sampling/modulation circuit 51 is applied to the counter 53 . During a predetermined period, the counter 53 counts the number of pulses in the received pulse train signal. Since the counting mode of the counter 53 is counting upwards from a counting reference value, the effect of adjusting the counting reference value by translation is equal to the counting result calculated by the translation adjustment counter 53, so the inventor applies this technical principle In the correction of the constant term error of the temperature measurement result.

Specifically, the counting reference value of the counter 53 is determined by the correction value CF provided by the correction value generating circuit 36 . In the correction value generation circuit 36, the constant term error dΔV _BE from the calculation circuit 35 is multiplied by the scaling factor A/(A-1) via the multiplier 41, and then is compared with the external system 20 via the adder 42 The temperature difference data ΔT are added together to synthesize the desired single correction value CF and stored in the correction register 43 . In other words, the embodiment shown in FIG. 5 achieves the purpose of shifting and converting the reference level REF in FIG. 4 by shifting and adjusting the counting reference value of the counter 53 . On the other hand, the frequency divider 54 divides the frequency of the clock signal CLK of the clock generator 52 to generate a lower frequency reset signal RST. In one embodiment, the frequency of the reset signal RST generated by the frequency divider 54 is obtained by dividing the frequency of the clock signal CLK of the clock generator 52 by 1024. Therefore, after 1024 cycles of the clock signal CLK, the counter 53 will be reset to the counting reference value, so as to restart counting. Likewise, the counting reference value is determined by the correction value CF provided by the correction value generation circuit 36 . In addition, the result counted by the counter 53 within 1024 cycles of the clock signal CLK is sent to the output register 55 and output to the outside as the temperature measurement result Tmp. The temperature measurement result Tmp is also updated according to the frequency of the reset signal RST.

While the present invention has been described by way of illustration of preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and similar arrangements apparent to those skilled in the art. Accordingly, the scope of the claims should be accorded the broadest interpretation to embrace all such modifications and similar arrangements.

Claims (9)

1, a kind of temperature measuring circuit comprises:

One electric current energizing circuit is used for applying in regular turn at least two electric current to thermal sensors, makes this thermal sensor produce at least two output signals accordingly;

One counting circuit is used for calculating an analog temperature signal in response to these at least two output signals, and it represents the detected temperature of this thermal sensor;

One correction value generating circuit is used to produce a corrected value; And

One analog to digital change-over circuit becomes a digital temperature signal according to a conversion reference level with this analog temperature conversion of signals,

Wherein, this conversion reference level translation adjustment according to this corrected value.

2, temperature measuring circuit as claimed in claim 1, wherein:

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.

3, temperature measuring circuit as claimed in claim 1, wherein:

This corrected value applies at least three electric currents to this thermal sensor in regular turn by this electric current energizing circuit and calculates, and makes this corrected value be used to revise a constant term error of this analog temperature signal.

4, temperature measuring circuit as claimed in claim 3, wherein:

This constant term error is produced by at least one series connection dead resistance of this thermal sensor.

5, temperature measuring circuit as claimed in claim 1, wherein:

This thermal sensor is arranged in the substrate of an ambient systems, and

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.

6, temperature measuring circuit as claimed in claim 1, wherein:

This analog to digital change-over circuit comprises:

One sampling/modulation circuit produces a pulse sequence signal in response to this analog temperature signal, and

One counter produces a count results in response to this pulse sequence signal in a cycle of being scheduled to, it represents the number of the pulse of this pulse sequence signal,

Wherein, this count results increases progressively from a reference value, and this reference value is set by this corrected value.

7, a kind of thermometry comprises:

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; And

According to a conversion reference level this analog temperature conversion of signals is become a digital temperature signal,

Wherein, this conversion reference level translation adjustment according to this corrected value.

8, a kind of electric current energizing circuit in order to excite a thermal sensor, comprises:

One measuring current source circuit is used to provide one first to measure electric current and one second measurement electric current;

One correcting current source circuit is used to provide a correcting current;

One correction control circuit is used to allow this first measurement electric current, this second measurement electric current and this correcting current to be applied to this thermal sensor in regular turn, so that measure the constant term error relevant for this thermal sensor; And

One circuit of measurement and control is used to allow this first measurement electric current and this second measurement electric current to be applied to this thermal sensor in regular turn, so that measure the temperature of this thermal sensor,

Wherein, this correction control circuit is activated carrying out the measurement of this constant term error than this circuit of measurement and control is more Zao, and

After this circuit of measurement and control was activated with the measurement of carrying out this temperature, this correction control circuit was shut-down operation.

9, electric current energizing circuit as claimed in claim 8, wherein:

This first measurement electric current is A a times of this second measurement electric current, and

This second measurement electric current is A a times of this correcting current, and wherein, A is greater than zero.

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