CN203298898U - Temperature calibration device for CMOS temperature sensors - Google Patents

Abstract

The utility model discloses a temperature calibration device for CMOS temperature sensors. The temperature calibration device comprises a CMOS temperature sensing circuit, a data processing unit, a slope register, an intercept register, a temperature value register and a standard thermometer. The temperature calibration device for CMOS temperature sensors can calibrate a temperature sensor to a precision of +/-0.2 DEC C with only two temperature testing points and without the need for an external voltage source, the calibration speed is high, no peripheral circuit is added, and the testing cost is greatly reduced.

Description

Temperature correction device for the CMOS temperature sensor

Technical field

The utility model relates to the CMOS temperature sensor, more specifically, is a kind of device of temperature correction for the CMOS temperature sensor.

Background technology

The integrated CMOS temperature sensor utilizes the parasitic PNP triode in CMOS technique to produce V as temperature-sensing element _BEWith Δ V _BETwo voltage signals with temperature correlation, wherein V _BEVoltage raises and reduces with temperature, Δ V _BEVoltage raises and increases with temperature.The readout of temperature can be with a variable α Δ V relevant to temperature linearity _BE(V _PTAT) a relative temperature independent constant α Δ V _BE+ V _BE(V _REF) proportionate relationship try to achieve, specifically as shown in Figure 1.

V _BEAt 25 ℃ of temperatures coefficient, be about-2mV/ ℃ Δ V _BEAt the temperatures coefficient of 25 ℃, depend on the current ratio of two PNP triodes, if adopt 1; 5 current ratios, Δ V _BEAt the about 0.14mV/ ℃ of the temperature coefficient of 25 ℃, so α=14 o'clock can obtain the V irrelevant with temperature variation at-55 ℃～125 ℃ _REF, wherein,

V _REF=α Δ V _BE+ V _BE(formula 1)

With ratio value μ as variable, wherein,

$\mathrm{\μ}=\frac{\mathrm{\α\Δ}{V}_{\mathrm{BE}}}{\mathrm{\α\Δ}{V}_{\mathrm{BE}}+V_{\mathrm{BE}}};$ (formula 2)

By following linear equation, can obtain the temperature readout:

T _OUT=A. μ+B (formula 3)

Wherein A ≈ 680, B ≈ 280, T _OUTIt is the temperature readout.

Process drift and chip package thereof can cause V _BEThe variation with temperature rate changes, thereby causes temperature readout T _OUTThe variation with temperature slope departs from ideal value 1.Fig. 2 shows temperature readout T in-55 ℃～125 ℃ temperature ranges _OUTVariation with temperature rate and V _BEVary with temperature the relation of rate.Work as V _BEWhen the absolute value of temperature variant straight slope is less than normal, T _OUTTemperature variant straight slope is bigger than normal; Work as V _BEWhen the absolute value of temperature variant straight slope is bigger than normal, T _OUTTemperature variant straight slope is less than normal.In Fig. 2, dash area represents T _OUTVary with temperature the scope of straight slope, as seen from the figure, the deviation of straight slope can reduce temperature sensing actuator temperature readout T _OUTPrecision.

The utility model content

In order to solve temperature readout T _OUTThe variation with temperature slope departs from ideal value and the problem that causes precision to reduce, the utility model proposes a kind of device of temperature correction for the CMOS temperature sensor.This device comprises CMOS temperature-sensitive circuit, data processing unit, slope register, intercept register, temperature value registers and standard thermo detector, wherein:

This CMOS temperature-sensitive circuit is connected with this data processing unit, and it has a temperature and characterizes predetermined variable, and the output temperature readout, and this temperature readout and this predetermined temperature sign amount are the preset lines sexual intercourse;

This slope register is connected with this data processing unit, be used to depositing slope default value or slope calibration value;

This intercept register is connected with this data processing unit, be used to depositing intercept default value or intercept calibration value;

This standard thermo detector is connected with this data processing unit, for determining two points for measuring temperature;

This temperature value registers is connected with this data processing unit, be used to being deposited with two temperature readouts of this CMOS temperature-sensitive circuit that these two points for measuring temperature are corresponding;

This data processing unit is for exporting and this preset lines sexual intercourse according to these two actual temperatures, determine two corresponding temperature sign amount output valves, and according to these two points for measuring temperature and these two temperature sign amount output valves, carry out actual line sexual intercourse match, determine this slope calibration value and this intercept calibration value.

Preferably, described data processing unit is microprocessor.

Temperature correction for CMOS temperature sensor device of the present utility model, do not need the impressed voltage source, only utilize two temperature test points just can in-55 ℃～125 ℃ temperature ranges, temperature sensor be calibrated to ± precision of 0.2 ℃, calibration speed is fast, do not increase peripheral circuit, therefore greatly reduce testing cost.

The accompanying drawing explanation

Fig. 1 is the linear relationship schematic diagram of output signal and the temperature of temperature-sensing element;

Fig. 2 is the schematic diagram that shows the linear relationship skew of CMOS temperature sensor output signal and readout;

Fig. 3 is the composition schematic diagram of the device of the temperature correction for the CMOS temperature sensor of the present utility model;

Fig. 4 utilizes temperature correction device in Fig. 3 to carry out the flow process signal intention of the method for temperature correction.

Embodiment

Below in conjunction with the drawings and specific embodiments, composition structure and the principle of work of the device of the temperature correction for the CMOS temperature sensor of the present utility model is elaborated.

As shown in Figure 3, for the composition schematic diagram of the device of the temperature correction for the CMOS temperature sensor of the present utility model, it comprises CMOS temperature-sensitive circuit 110, data processing unit 140, slope register 120, intercept register 130, temperature value registers 150 and standard thermo detector 160.

More specifically, CMOS temperature-sensitive circuit 110 is connected with data processing unit 140, and it has a temperature and characterizes predetermined variable, and the output temperature readout, and this temperature readout and this predetermined temperature sign amount are the preset lines sexual intercourse.As mentioned above, this temperature characterize predetermined variable be one with interior two the voltage signal V of CMOS temperature-sensitive circuit 110 _BEWith Δ V _BERelevant variable μ (as shown in Equation 2), and this variable and temperature readout linear (as shown in Equation 3).

In this embodiment, CMOS temperature-sensitive circuit 110 can be the integrated CMOS temperature-sensitive circuit that the conventional parasitic PNP triode by in CMOS technique forms as temperature-sensing element.And data processing unit 140 can be any treating apparatus that can carry out linear relationship computing and output, comprises central processing unit, digital signal processor, Special Purpose Programmable logic chip etc.In this embodiment, data processing unit 140 is microprocessor.

Slope register 120 is connected with data processing unit 140, be used to depositing slope default value or slope calibration value.Intercept register 130 is connected with data processing unit 140, be used to depositing intercept default value or intercept calibration value.

As mentioned above, above-mentioned preset lines sexual intercourse (formula 3), determined by slope default value A and intercept default value B, before calibrating, this slope default value A and intercept default value B can be pre-deposited in corresponding slope register 120 and intercept register 130.And after calibrating, slope register 120 can be used for depositing the slope calibration value through calibration, and intercept register 130 can be used for depositing the intercept calibration value through calibration.

Standard thermo detector 160 is connected with data processing unit 140, for determining two points for measuring temperature.Standard thermo detector 160 can adopt conventional standard thermometer, accurately to determine point for measuring temperature.In this utility model, need be at least to two point for measuring temperature T _W1, T _W2Determine, to carry out the linear relationship calibration.

Temperature value registers 150 is connected with data processing unit 140, be used to being deposited with two temperature readout T1, T2 of the CMOS temperature-sensitive circuit 110 that these two points for measuring temperature are corresponding.At two actual point for measuring temperature T _W1, T _W2Under, CMOS temperature-sensitive circuit 110 calculates via data processing unit 140, according to linear relationship, can produce two temperature readouts, and these two temperature readouts can be deposited with in temperature value registers 150 with the calibration process for follow-up.

This data processing unit 140, for according to two actual temperature output T1, T2 and this preset lines sexual intercourse (formula 3), is determined two corresponding temperature sign amount output valve μ ₁, μ ₂, and according to two point for measuring temperature T _W1, T _W2With two temperature sign amount output valve μ ₁, μ ₂, carry out actual line sexual intercourse match, determine this slope calibration value and this intercept calibration value.Thus, complete the calibration to linear relationship.Concrete data handling procedure will be described in more detail hereinafter.

Below the method for utilizing this calibrating installation to calibrate is described.As shown in Figure 4, be the process flow diagram of the method, the method comprises step S100-S400 generally.Below in conjunction with Fig. 3,4, each step is specifically described.

In step S100, determine that the temperature of this CMOS temperature sensor characterizes the preset lines sexual intercourse of predetermined variable and temperature readout variable, this preset lines sexual intercourse comprises slope default value and intercept default value.

As shown in above-mentioned formula 3, the preset lines sexual intercourse is:

T _OUT＝A.μ+B；

Wherein, T _OUTFor temperature readout variable, μ is that temperature characterizes predetermined variable, and A is the slope default value, and B is the intercept default value.

As can be seen from above, T _OUTBy A, B determines with the preset lines sexual intercourse of μ, and A, B value can be default values arbitrarily, but for calibration conveniently, slope default value and intercept default value can be set as the circuit simulation value.As mentioned above, slope default value and intercept default value can be deposited with respectively in slope register 120 and intercept register 130.

S200, under two points for measuring temperature, utilize two temperature readouts of CMOS temperature sensor, and, according to this preset lines sexual intercourse, determine two corresponding temperature sign amount output valves.

These two point for measuring temperature T _W1, T _W2Can be any two temperature values in the effective output temperature of CMOS temperature sensor, example is T as shown in Figure 2 _W1=-55 ℃ and T _W2=125 ℃.And, according to the slope default value A in preset lines sexual intercourse in formula 3 and intercept default value B, calculate two temperature sign amount output valves under these two points for measuring temperature.

Two temperature sign amount output valves specifically are calculated as follows:

T1=A μ ₁+ B; (formula 4)

T2＝Aμ ₂+B

Thereby draw:

μ ₁=(T1-B)/A; (formula 5)

μ ₂＝(T2-B)/A

In formula 4,5, μ ₁, μ ₂Be respectively described two temperature characterization value output valves, T1, T2 are respectively two temperature readouts under described two points for measuring temperature.This calculating can complete in data processing unit 140.

At step S300, according to two point for measuring temperature T _W1, T _W2With these two temperature sign amount output valve μ ₁, μ ₂, carry out actual line sexual intercourse match, determine slope calibration value and intercept calibration value.

This calculating can complete in data processing unit.Particularly, determine that the computing formula of slope calibration value and intercept calibration value is as follows:

At first, each point for measuring temperature and corresponding temperature sign amount output are carried out to actual line sexual intercourse match:

T _W1=A _cμ ₁+ B; (formula 6)

T _W2＝A _cμ ₂+B

And then draw:

A _c=(T _W2-T _W1)/(μ ₂-μ ₁); (formula 7)

B _c＝-(Aμ ₂-TW ₂)

Wherein, A _CFor slope calibration value, B _CFor intercept calibration value, T _W1, T _W2For described two points for measuring temperature.

Then, can be by the slope calibration value A that calculates _CWith intercept calibration value B _CInsert respectively slope register 120 and intercept register 130, thereby complete the calibration to the CMOS temperature sensor.

In sum, calibrating installation of the present utility model, do not need the impressed voltage source, only need two points for measuring temperature can complete the temperature correction of in certain temperature range (as-55 ℃～125 ℃), thereby the precision of CMOS temperature sensor can be increased to ± precision of 0.2 ℃, and this calibrating installation calibration speed is fast, does not increase peripheral circuit, thereby greatly reduces testing cost.

Claims (2)

1. the device of the temperature correction for the CMOS temperature sensor, is characterized in that, comprises CMOS temperature-sensitive circuit, data processing unit, slope register, intercept register, temperature value registers and standard thermo detector, wherein:

This CMOS temperature-sensitive circuit is connected with this data processing unit, and it has a temperature and characterizes predetermined variable, and the output temperature readout, and this temperature readout and this predetermined temperature sign amount are the preset lines sexual intercourse;

This slope register is connected with this data processing unit, be used to depositing slope default value or slope calibration value;

This intercept register is connected with this data processing unit, be used to depositing intercept default value or intercept calibration value;

This standard thermo detector is connected with this data processing unit, for determining two points for measuring temperature;

This temperature value registers is connected with this data processing unit, be used to being deposited with two temperature readouts of this CMOS temperature-sensitive circuit that these two points for measuring temperature are corresponding;

This data processing unit is for exporting and this preset lines sexual intercourse according to these two actual temperatures, determine two corresponding temperature sign amount output valves, and according to these two points for measuring temperature and these two temperature sign amount output valves, carry out actual line sexual intercourse match, determine this slope calibration value and this intercept calibration value.

2. the device of the temperature correction for the CMOS temperature sensor according to claim 1, is characterized in that, described data processing unit is microprocessor.

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