JP5440521B2 - Sensitivity temperature compensation circuit - Google Patents

Description

  The present invention relates to a sensitivity temperature special correction circuit that corrects a sensitivity temperature coefficient of a sensor unit that outputs a detection signal corresponding to a physical quantity.

  Conventionally, as a sensitivity temperature special correction circuit for correcting a sensitivity temperature coefficient of a sensor unit that outputs a detection signal corresponding to a physical quantity, a circuit including a sensitivity temperature special adjustment unit having an operational amplifier and a resistor has been disclosed (for example, , See Patent Document 1).

  Specifically, in the sensitivity temperature special adjustment unit in the sensitivity temperature special correction circuit, an input resistor and a feedback resistor are connected to the operational amplifier, and the input temperature and the feedback resistor have different resistance temperature coefficients. That is, the resistance temperature coefficient of the sensitivity temperature special correction circuit (sensitivity temperature special adjustment unit) is expressed as (TCRi−TCRf), where TCRi is the resistance temperature coefficient of the input resistance and TCRf is the resistance temperature coefficient of the feedback resistance.

  Therefore, in such a sensitivity temperature special correction circuit, the sensitivity temperature coefficient of the output signal to be output is reduced by appropriately selecting the resistance temperature coefficient of the input resistance and the feedback resistance in consideration of the sensitivity temperature coefficient of the sensor unit. be able to. For example, when the sensitivity temperature coefficient of the sensor unit (detection signal of the sensor unit) is 500 ppm / ° C., the resistance temperature coefficient TCRi of the input resistance is set to 800 ppm / ° C., and the resistance temperature coefficient TCRf of the feedback resistor is set to 1200 pppm / ° C. As a result, the sensitivity temperature coefficient of the sensitivity temperature special correction circuit becomes −400 ppm / ° C., so that the sensitivity temperature coefficient of the output signal output from the sensitivity temperature special correction circuit can be reduced to 100 ppm / ° C.

JP 2003-42870 A

  However, such a sensitivity temperature special correction circuit has a problem that the sensitivity temperature coefficient cannot be corrected more than the difference between the input resistance and the feedback resistance with respect to the sensitivity temperature coefficient of the sensor unit. That is, as described above, when the resistance temperature coefficient TCRi of the input resistance is 800 ppm / ° C. and the resistance temperature coefficient TCRf of the feedback resistance is 1200 pppm / ° C., the sensitivity temperature coefficient of the sensor unit (detection signal of the sensor unit) It can only be reduced to -400 ppm / ° C. At present, a sensitivity temperature special correction circuit that can further reduce the sensitivity temperature coefficient of the output signal is desired.

  The present invention has been made in view of the above points, and an object thereof is to provide a sensitivity temperature special correction circuit capable of reducing the sensitivity temperature coefficient of an output signal.

  In order to achieve the above object, according to the first aspect of the present invention, a first operational amplifier in which a detection signal corresponding to a physical quantity is input from the sensor unit (30) and a reference voltage is input via a variable resistor (R2). (1), and a first sensitivity temperature special adjustment unit (10) configured by connecting the variable resistor (R2) and the variable resistor (R1) as a feedback resistor having a different resistance temperature coefficient to the first operational amplifier (1). ), And a feedback resistor (R3) having a second operational amplifier (2) to which the output signal outputted from the first sensitivity temperature special adjustment unit (10) is inputted, and connected to the second operational amplifier (2), A variable resistor having a resistance temperature coefficient different from that of the feedback resistor (R3) connected to the input terminal of the second operational amplifier (2) and the output terminal of the first operational amplifier (1) and connected to the second operational amplifier (2). (R4) and a second sensitivity temperature characteristic It is characterized in that it comprises settling section (20), the.

  Such a sensitivity temperature special correction circuit includes a first sensitivity temperature special adjustment unit (10) and a second sensitivity temperature special adjustment unit (20) configured as described above. That is, the first and second sensitivity temperature special adjustment units (10, 20) are different from the conventional sensitivity temperature special correction circuit in which the sensitivity temperature coefficient of the output signal is corrected only by the first sensitivity temperature special adjustment unit (10). Can correct the sensitivity temperature characteristic coefficient. Therefore, by appropriately selecting the resistance temperature coefficient of the variable resistors (R1, R2, R4), the resistance values of the variable resistors (R1, R2, R4) and the resistor (R3), the detection signal of the sensor unit (30) The sensitivity temperature coefficient of the output signal output from the second operational amplifier (2) is made smaller than the value obtained by subtracting the difference between the resistance temperature coefficients of the variable resistors (R1, R2) connected to the first operational amplifier (1) from the sensitivity temperature coefficient. can do.

  Further, as in the invention described in claim 2, the second operational amplifier (2) is a variable resistor (R5) having the same resistance temperature coefficient as the feedback resistor (R3) connected to the second operational amplifier (2) at the inverting input terminal. ) And the detection signal of the sensor unit (30) is input to the inverting input terminal via the variable resistor (R5), and the output signal of the first sensitivity temperature special adjustment unit (10) is input to the inverting input terminal. Can be.

  According to this, since the electric signal from the sensor unit (30) is input to the second operational amplifier (2) through the variable resistor (R5) having the same resistance temperature coefficient as the feedback resistor (R3), the variable resistor ( By appropriately selecting R5), it is possible to suppress variation in the amplification factor at room temperature of the sensitivity temperature special correction circuit from product to product.

  Then, as in the third aspect of the invention, the electric signal from the sensor unit (3) via the third operational amplifier (3) constituting the voltage follower in the first operational amplifier (1) and the second operational amplifier (2). Can be entered.

  Further, as in the fourth aspect of the invention, the electric signal from the sensor unit (30) can be input to the non-inverting input terminal of the first operational amplifier (1).

  Further, as in the invention described in claim 5, the first sensitivity temperature special adjustment unit (10) is used as a feedback resistor having a reference voltage inputted through a variable resistor and having a resistance temperature coefficient different from that of the variable resistor. The fourth operational amplifier having a variable resistor is provided, and the inverting input terminal of the second operational amplifier (2) can be connected to the output terminal of the first operational amplifier (2) through the fourth operational amplifier.

  Further, as in the invention described in claim 6, the first sensitivity temperature special adjustment unit (1) is added to the first operational amplifier (1), and the reference voltage is inputted through the variable resistor (R7) and the variable. The fourth operational amplifier (4) for inverting provided with a variable resistor (R6) as a feedback resistor having a resistance temperature coefficient different from that of the resistor (R7) can be provided. The electric signal from the sensor unit (30) is input to the inverting input terminal to the first operational amplifier (1), and the electric signal from the first operational amplifier (1) is input to the inverting input terminal to the fourth operational amplifier (4). Thus, the inverting input terminal of the second operational amplifier (2) can be connected to the output terminal of the first operational amplifier (2) through the fourth operational amplifier (4).

  Thus, the detection signal from the sensor unit (30) can be input to the inverting input terminal of the first operational amplifier (1).

  And like invention of Claim 7, a variable resistance can be comprised by one resistance selectively connected from the some resistance via the switching element.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a circuit diagram of the sensitivity temperature characteristic correction circuit in 1st Embodiment of this invention. It is a circuit diagram of the sensitivity temperature characteristic correction circuit in other embodiment of this invention.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a sensitivity temperature special correction circuit in the present embodiment.

  As shown in FIG. 1, the sensitivity temperature special correction circuit 100 includes a first sensitivity temperature special adjustment unit 10 having a first operational amplifier 1, a second sensitivity temperature special adjustment unit 20 having a second operational amplifier 2, and a voltage follower. It is set as the structure provided with the 3rd operational amplifier 3 which comprises. The sensor unit 30 and the CV conversion circuit 31 are connected.

  The sensor unit 30 has a sensitivity temperature coefficient, for example, an acceleration sensor that includes a movable electrode and a fixed electrode, and changes the capacitance between the movable electrode and the fixed electrode according to the applied acceleration. It is done. Of course, the sensor unit 30 is not limited to this, and may be, for example, a pressure sensor, an angular velocity sensor, a humidity sensor, or the like.

  The first sensitivity temperature special adjustment unit 10 includes a first operational amplifier 1 and variable resistors R1 and R2. The non-inverting input terminal of the first operational amplifier 1 is connected to the output terminal of the third operational amplifier 3, and the detection signal from the sensor unit 30 is input via the third operational amplifier 3. The inverting input terminal of the first operational amplifier 1 is connected to the output terminal via a variable resistor R1 as a feedback resistor, and the reference voltage Vref is input via the variable resistor R2. The variable resistors R1 and R2 have different resistance temperature coefficients.

  Note that the variable resistors R1 and R2 are configured by one resistor selectively connected from a plurality of resistors having different resistance temperature coefficients through a switching element, although not particularly illustrated. The plurality of resistors having different resistance temperature coefficients are, for example, a resistor formed of chrome silicon, a diffused resistor, a resistor formed of polysilicon, an ON resistance of a transistor, and the like.

  The second sensitivity temperature special adjustment unit 20 includes a second operational amplifier 2, a resistor R3, and variable resistors R4 and R5. The inverting input terminal of the second operational amplifier 2 is connected to the output terminal via a feedback resistor (hereinafter simply referred to as a resistor) R3. The inverting input terminal is connected to the output terminal of the first operational amplifier 1 through the variable resistor R4, and the output of the third operational amplifier 3 through the variable resistor R5 having the same resistance temperature coefficient as the resistor R3. Connected to the terminal. The reference voltage Vref is input to the non-inverting input terminal of the second operational amplifier 2.

  The variable resistor R4, like the variable resistors R1 and R2, is not particularly illustrated, but is composed of one resistor selectively connected from a plurality of resistors having different resistance temperature coefficients via a switching element. Yes.

  Similarly to the variable resistors R1, R2, and R4, the variable resistor R5 includes one resistor that is selectively connected from among a plurality of resistors via a switching element. The resistance temperature coefficient of each of the resistors is equal to that of the resistor R3. That is, only the resistance values of the resistors constituting the variable resistor R5 are different from each other. This is due to the following reason.

  That is, the variable resistors R1, R2, and R4 connected to the first operational amplifier 1 are configured by one resistor selectively connected from a plurality of resistors having different resistance temperature coefficients as described above, and depending on the selected resistor. Resistance value is different. In this case, when the variable resistor R5 having the same resistance temperature coefficient as the resistor R3 is not provided, the amplification factor at room temperature of the sensitivity temperature special correction circuit 100 varies depending on the resistance values of the resistors configuring the variable resistors R1, R2, and R4. End up. Therefore, by appropriately adjusting the variable resistor R5, the amplification factor at room temperature of the sensitivity temperature special correction circuit 100 can be set to a desired value. That is, the variable resistor R5 functions to suppress variations in the amplification factor of the sensitivity temperature special correction circuit 100.

  The third operational amplifier 3 constitutes a voltage follower, and is connected to the sensor unit 30 via the CV conversion circuit 31. And the detection signal of the sensor part 30 input via the CV conversion circuit 31 is converted into a low impedance and output.

  Next, the operation of the sensitivity temperature special correction circuit 100 will be described with reference to FIG. Hereinafter, the sensitivity temperature special correction circuit 100 will be described in which the resistance temperature coefficients of the variable resistors R1, R3, and R5 are equal and the resistance temperature coefficients of the variable resistors R2 and R4 are equal.

  First, the detection signal input to the third operational amplifier 3 is Vin, the sensitivity temperature coefficient of the detection signal Vin is α, the resistance temperature coefficient of the variable resistors R1, R3, R5 is β, the resistance temperature of the variable resistors R2, R4 It is assumed that the coefficient is γ and the reference voltage Vref has no temperature coefficient. In the present embodiment, the detection signal input to the third operational amplifier 3 is a detection signal from the sensor unit 30 input via the CV conversion circuit 31, and the sensitivity temperature coefficient of the detection signal Vin. In other words, it is the sensitivity temperature coefficient of the sensor unit 30.

  In this case, if the temperature characteristics of the resistors R1 to R5 and the detection signal Vin are not considered, the output signal V1 from the third operational amplifier 3, the output signal V2 from the first operational amplifier 1, and the output signal V0 from the second operational amplifier 2 are respectively It becomes like the following formula.

次に、数式３に数式１および２を代入し、検出信号Ｖｉｎの感度温度係数、抵抗Ｒ１〜Ｒ５の抵抗温度係数を考慮すると、上記数式３は次式のようになる。

Next, when Expressions 1 and 2 are substituted into Expression 3, and the sensitivity temperature coefficient of the detection signal Vin and the resistance temperature coefficients of the resistors R1 to R5 are taken into consideration, the above Expression 3 becomes as follows.

上記数式４において、Ｔｅｍｐはセンサ部３０の周囲の温度、２５は室温であり、（Ｔｅｍｐ−２５）はセンサ部３０の周囲の温度変化を示している。この数式４より、抵抗Ｒ１〜Ｒ５の抵抗値、抵抗Ｒ１〜Ｒ５の抵抗温度係数を適宜選択することにより、第２オペアンプ２から出力される出力信号の感度温度係数を所望の値にすることができることが理解できる。

In Equation 4, Temp is the ambient temperature of the sensor unit 30, 25 is room temperature, and (Temp-25) indicates a change in the ambient temperature of the sensor unit 30. By appropriately selecting the resistance values of the resistors R1 to R5 and the resistance temperature coefficients of the resistors R1 to R5 from Equation 4, the sensitivity temperature coefficient of the output signal output from the second operational amplifier 2 can be set to a desired value. I understand what I can do.

  Next, specific effects will be described. Hereinafter, a case where the reference voltage Vref = 2.5 V and the temperature around the sensor unit 30 is changed from room temperature (25 ° C.) to 85 ° C. will be described as an example.

  For example, the resistance value of the variable resistor R1 = 10 kΩ, the resistance value of the variable resistor R2 = 10 kΩ, the resistance value of the resistor R3 10 kΩ, the resistance value of the variable resistor R4 = 25 kΩ, the resistance value of the variable resistor R5 = 50 kΩ, and the sensitivity of the detection signal Vin It is assumed that the temperature coefficient α = 2400 ppm / ° C., the resistance temperature coefficient β of the variable resistors R1, R3, and R5 = 100 ppm / ° C., and the resistance temperature coefficient γ of the variable resistors R2, R4 = 1300 ppm / ° C. The detection signal Vin is assumed to be 2 V to 3 V within a range from room temperature (25 ° C.) to 85 ° C.

  In this case, when the detection signal Vin is 2V, the output signal V0 output from the second operational amplifier 2 is 2.695V when the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient are substituted into Equation 4. When the detection signal Vin is 3V, the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient are substituted into Equation 4 to obtain 1.641V. That is, the output signal output from the second operational amplifier 2 (sensitivity temperature characteristic correction circuit 100) has a voltage difference of 1.054V when 2V is input as the detection signal Vin and when 3V is input. Yes. That is, by selecting the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient as described above, the sensitivity temperature coefficient of the output signal output from the sensitivity temperature special correction circuit 100 can be reduced to 900 ppm / ° C.

  For example, the resistance value of the resistor R1 = 30 kΩ, the resistance value of the resistor R2 = 10 kΩ, the resistance value of the resistor R3 10 kΩ, the resistance value of the resistor R4 = 50 kΩ, the resistance value of the resistor R5 = 50 kΩ, and the sensitivity temperature coefficient α of Vin = It is assumed that the resistance temperature coefficient β of the variable resistance R1, the resistance R3, and the variable resistance R5 is 100 ppm / ° C., and the resistance temperature coefficient γ of the variable resistances R2 and R4 is 1300 ppm / ° C. The detection signal Vin is assumed to be 2 V to 3 V within a range from room temperature (25 ° C.) to 85 ° C.

  In this case, when the detection signal Vin is 2V, the output signal V0 output from the second operational amplifier 2 is 2.693V when the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient are substituted into Equation 4. When the detection signal Vin is 3V, the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient are substituted into Equation 4 to obtain 1.653V. In other words, the output signal output from the second operational amplifier 2 (sensitivity temperature characteristic correction circuit 100) has a voltage difference of 1.040V when 2V is input as the detection signal Vin and when 3V is input. Yes. That is, by selecting the resistance value, the resistance temperature coefficient, and the sensitivity temperature coefficient as described above, the sensitivity temperature coefficient of the output signal output from the sensitivity temperature special correction circuit 100 can be reduced to 667 ppm / ° C.

  As described above, according to the sensitivity temperature characteristic correction circuit 100 of the present embodiment, the resistance temperature coefficient of the variable resistors R1, R2, and R4 and the resistance values of the variable resistors R1, R2, R4, R5, and the resistor R3 are appropriately selected. By doing so, the sensitivity temperature coefficient of the output signal can be corrected more than the difference between the resistance temperature coefficients of the variable resistor R1 and the variable resistor R2 connected to the first operational amplifier 1. That is, in the above example, the difference in resistance temperature coefficient between the variable resistor R1 and the variable resistor R2 is 1200 ppm / ° C. Therefore, in the conventional sensitivity temperature special correction circuit, the sensitivity temperature coefficient of the detection signal Vin is 2400 ppm / ° C. In this case, the sensitivity temperature coefficient of the output signal can be reduced only to 1200 ppm / ° C. However, in the sensitivity temperature special correction circuit 100 of the present embodiment, as described above, the sensitivity temperature coefficient of the output signal can be reduced to 900 ° C./ppm or 667 ppm / ° C., and the resistances of the variable resistors R1, R2, and R4. The sensitivity temperature coefficient of the output signal can be further reduced by appropriately selecting the temperature coefficient and the resistance values of the variable resistors R1, R2, R4, R5 and the resistor R3.

Next, an actual adjustment procedure will be described. In such a sensitivity temperature characteristic correction circuit 100, an operator first selectively turns on any switching element connected to the variable resistors R1, R2, R4, and R5. The resistance temperature coefficient of the sensitivity temperature special correction circuit 100 is set to zero. Then, it connects with the sensor part 30 and the sensitivity temperature coefficient of the sensor part 30 is measured. That is, it is measured how the sensitivity of the sensor unit 30 changes when the temperature is changed. Next, the resistance temperature coefficients of the variable resistors R1, R2, and R4 are selected so as to cancel the measured sensitivity temperature coefficient of the sensor unit 30, and the amplification factor of the sensitivity temperature special correction circuit 100 is set to a desired value. The resistance value of the variable resistor R5 is selected.

  As described above, the sensitivity temperature special correction circuit 100 of the present embodiment includes the first sensitivity temperature special adjustment unit 10 and the second sensitivity temperature special adjustment unit 20 having the above-described configuration. For this reason, the resistance temperature coefficient of the variable resistors R1, R2, R4 and the resistance values of the variable resistors R1, R2, R4, R5 and the resistor R3 are appropriately selected to obtain the first from the sensitivity temperature coefficient of the detection signal of the sensor unit 30. The sensitivity temperature coefficient of the output signal output from the second operational amplifier 2 (sensitivity temperature special correction circuit 100) can be made smaller than the value obtained by subtracting the difference between the resistance temperature coefficients of the variable resistors R1 and R2 connected to the operational amplifier 1. .

  A detection signal from the third operational amplifier 3 is input to the inverting input terminal of the second operational amplifier 2 through a variable resistor R5 having the same resistance temperature coefficient as the resistor R3. Therefore, by adjusting the resistance value of the variable resistor R5, it is possible to adjust the amplification factor at room temperature of the sensitivity temperature special correction circuit 100, and it is possible to suppress the variation of the amplification factor for each product.

(Other embodiments)
Although the first embodiment has been described as having the third operational amplifier 3 constituting the voltage follower, the third operational amplifier 3 may not be provided. That is, the detection signal from the sensor unit 30 may be directly input to the first operational amplifier 1 and the second operational amplifier 2.

  In the first embodiment, the case where the resistance temperature coefficients of the variable resistors R1, R3, and R5 are equal and the resistance temperature coefficients of the variable resistors R2 and R4 are equal is described. The resistance temperature coefficient of R3 may be different, and the resistance temperature coefficients of the variable resistance R2 and the variable resistance R4 may be different.

  Furthermore, in the first embodiment, the example in which the non-inverting input terminal of the first operational amplifier 1 is connected to the output terminal of the third operational amplifier 1 has been described. However, the inverting input terminal of the first operational amplifier 1 is the output of the third operational amplifier 1. It can also be connected to a terminal. In this case, since the output of the first operational amplifier 1 is inverted, it may be configured to include an operational amplifier that further inverts the output of the first operational amplifier 1. FIG. 2 is a circuit diagram of a sensitivity temperature characteristic correction circuit 100 according to another embodiment.

  As shown in FIG. 2, the first sensitivity temperature special adjustment unit 10 includes an inversion fourth operational amplifier 4 in addition to the first operational amplifier 1. The inverting input terminal of the first operational amplifier 1 is connected to the output terminal of the third operational amplifier, the non-inverting input terminal is connected to the output terminal via the variable resistor R1, and the reference voltage via the variable resistor R2. Vref is input. Further, the inverting input terminal of the fourth operational amplifier 4 is connected to the output terminal of the first operational amplifier 1, and the non-inverting input terminal is connected to the output terminal via the variable resistor R6 and is also connected to the reference via the variable resistor R7. The voltage Vref is input. Note that the variable resistors R6 and R7 have different resistance temperature coefficients.

  As described above, when the inverting input terminal of the first operational amplifier 1 is connected to the output terminal of the third operational amplifier 3, the signal output from the output terminal of the first operational amplifier 1 becomes an inverted signal. The special adjustment unit 10 may be provided with a fourth operational amplifier 4 for inversion. That is, when the inverting input terminal of the first operational amplifier 1 is connected to the output terminal of the third operational amplifier 3, the number of operational amplifiers including the first operational amplifier 1 is an even number in the first sensitivity temperature special adjustment unit 10. In this way, the signal output from each operational amplifier may be an inverted signal. In addition, by configuring the first sensitivity temperature special adjustment unit 10 with a plurality of operational amplifiers, the sensitivity temperature coefficient of the output signal can be further reduced.

  Furthermore, also in the said 1st Embodiment, the 1st sensitivity temperature special adjustment part 10 can also be set as the structure which has several operational amplifier. That is, for example, the first sensitivity temperature special adjusting unit 10 is variable as a feedback resistor having a reference temperature input to the first operational amplifier 1 and the inverting input terminal via a variable resistor and having a variable temperature coefficient of resistance with the variable resistor. The fourth operational amplifier 4 may be configured to include a resistor and to which the inverting input terminal and the output terminal of the first operational amplifier 1 are connected. Then, the inverting input terminal of the second operational amplifier 10 can be connected to the output terminal of the first operational amplifier 1 through the fourth operational amplifier 4.

  In the first embodiment, the example in which the output signal from the third operational amplifier 3 is input to the second operational amplifier 2 via the variable resistor R5 has been described. However, the output from the third operational amplifier 3 is input to the second operational amplifier 2. A configuration in which no signal is input may be employed. Even in such a configuration, the first and second sensitivity temperature special adjustment units 10 are different from the conventional sensitivity temperature special correction circuit in which the sensitivity temperature coefficient of the output signal is corrected only by the first sensitivity temperature special adjustment unit 10. , 20 can correct the sensitivity temperature coefficient of the output signal, so that the sensitivity temperature coefficient of the output signal can be reduced.

DESCRIPTION OF SYMBOLS 1 1st operational amplifier 2 2nd operational amplifier 3 3rd operational amplifier 10 1st sensitivity temperature special adjustment part 20 2nd sensitivity temperature special adjustment part R1 Variable resistance R2 Variable resistance R3 Resistance R4 Variable resistance R5 Variable resistance 30 Sensor part

Claims (7)

The first operational amplifier (1) includes a first operational amplifier (1) to which a detection signal corresponding to a physical quantity is input from the sensor unit (30) and a reference voltage is input via a variable resistor (R2). A first sensitivity temperature adjustment unit (10) configured by connecting a variable resistor (R2) and a variable resistor (R1) as a feedback resistor having a different resistance temperature coefficient;
A feedback resistor (R3) connected to the second operational amplifier (2), having a second operational amplifier (2) to which an output signal outputted from the first sensitivity temperature special adjustment unit (10) is inputted; Connected to the input terminal of the second operational amplifier (2) and to the output terminal of the first operational amplifier (1), the feedback resistor (R3) connected to the second operational amplifier (2) and the resistance temperature coefficient A sensitivity temperature characteristic correction circuit comprising a second sensitivity temperature characteristic adjustment unit (20) having a different variable resistor (R4).   The second operational amplifier (2) includes an inverting input terminal including a variable resistor (R5) having a resistance temperature coefficient equal to that of the feedback resistor (R3) connected to the second operational amplifier (2). The detection signal of (30) is input to the inverting input terminal via the variable resistor (R5), and the output signal of the first sensitivity temperature special adjustment unit (10) is input to the inverting input terminal. The sensitivity temperature characteristic correction circuit according to claim 1, wherein   The detection signal from the sensor unit (3) is input to the first operational amplifier (1) and the second operational amplifier (2) through a third operational amplifier (3) constituting a voltage follower. The sensitivity temperature characteristic correction circuit according to claim 2.   The sensitivity temperature according to any one of claims 1 to 3, wherein the detection signal from the sensor unit (30) is input to the non-inverting input terminal of the first operational amplifier (1). Special correction circuit. The first sensitivity temperature special adjustment unit (10) includes a fourth operational amplifier including a reference voltage input via a variable resistor and a variable resistor as a feedback resistor having a resistance temperature coefficient different from that of the variable resistor.
5. The sensitivity temperature characteristic correction according to claim 4, wherein an inverting input terminal of the second operational amplifier (2) is connected to an output terminal of the first operational amplifier (1) through the fourth operational amplifier. circuit. In addition to the first operational amplifier (1), the first sensitivity temperature special adjustment unit (1) receives a reference voltage via a variable resistor (R7), and the variable resistance (R7) and the resistance temperature coefficient. A fourth operational amplifier (4) having a variable resistor (R6) as a different feedback resistor is provided, and the detection signal from the sensor unit (30) is input to the inverting input terminal of the first operational amplifier (1). The output signal from the first operational amplifier (1) is input to the inverting input terminal of the fourth operational amplifier (4).
The inverting input terminal of the second operational amplifier (2) is connected to the output terminal of the first operational amplifier (1) through the fourth operational amplifier (4). The sensitivity temperature characteristic correction circuit according to claim 1.   The sensitivity according to any one of claims 1 to 6, wherein the variable resistor is configured by one resistor selectively connected from among a plurality of resistors via a switching element. Temperature compensation circuit.

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