JPH11194061A - Pressure sensor driving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accurate and small sensor driving circuit by using a digital control signal where a temperature signal from a thermally sensitive means for measuring temperature of the sensor circuit is binary-coded, by performing digital control, and by compensating the temperature of a sensor. SOLUTION: A semiconductor pressure sensor 20 is calibrated at each preset temperature, and the gain adjustment resistance value and offset adjustment resistance value of the pressure sensor 20 in a specific temperature range are stored into a CPU 33. When pressure is measured, the temperature of the pressure sensor 20 is simultaneously detected by a thermally sensitive resistor 31, an analog signal from the thermally sensitive resistor 31 is binary-coded by an A/D converter 32 and is converted to a digital signal for sending to the CPU 33, and the offset adjustment resistance value and the gain adjustment resistance value are determined according to data being subjected to temperature calibration and storage in advance. The digital signal corresponding to the determined values is sent to a digital trimmer 34, and the resistance value of each terminal being connected to an addition circuit 43 and a non-inverted amplification circuit 42 are changed and adjusted, thus adjusting the gain of the sensor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor driving circuit, and more particularly, to a sensor driving circuit having a temperature compensation circuit for a semiconductor pressure sensor that changes an output voltage or an output current according to an applied pressure.

[0002]

2. Description of the Related Art Conventionally, a sensor driving technique having such a temperature compensation circuit is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-11370.
9 discloses a pressure difference measuring method and a displacement measuring device. FIG. 2 shows a configuration diagram of this conventional displacement measuring device.

[0003] A displacement measuring device 200 shown in FIG. 2 detects capacitances C1 and C2 between the diaphragm 1 and the fixed electrodes 3 and 4 which are displaced by receiving a pressure difference on both surfaces to determine a pressure difference. . In such an apparatus for measuring capacitance, it is necessary to correct the stray capacitance irrespective of the displacement of the diaphragm by a measurement range or temperature in order to measure with high accuracy.

In the displacement measuring apparatus of the prior art, in a calibration mode, the microcomputer 205 pre-charges the electrostatic force via the time constant measuring device 202, the A / D converter 203, and the timer counter 206 under a plurality of known pressure differences. Measure the capacitances C1 and C2,
From this data, a constant necessary for the correction of the stray capacitance and the pressure detection is obtained and stored in the memory 204. Further, the calibration is performed at each predetermined temperature, and a constant is stored for each temperature. In the measurement mode, the capacitance is measured by the sensor 201 and the measured temperature is measured by the temperature detector 214 at the same time. The measured pressure difference is calculated from the measured capacitances C1 and C2 and the constant stored in the memory 204, and the D / A converter 20
7. Output from the converter via the V / I converter 209. As a result, adjustment performed using hardware such as a compensation capacitor is simplified without impairing measurement accuracy. In such a displacement measuring device 200, the output frequency of the sensor 201 is measured using the microcomputer 205, and this is measured by the A / D converter.
The digital signal is coded through the converter 203 and the microcomputer 205 performs logical temperature compensation on the digital signal.

[0005]

However, in the displacement measuring apparatus 200 described above, the analog output of the sensor 201 is once converted into a digital signal via the microcomputer 205, and then the temperature is compensated digitally. Therefore, the number of digital ICs constituting a digital circuit such as an A / D converter and a timer counter increases, so that the scale of the circuit increases, and the cost of parts required for the circuit and the assembling time increase. There was a problem that it became expensive. In addition, digital compensation
In the case where the operation is performed in step 05, there is a problem that software for compensation is required, which leads to an increase in production cost. Further, in order to increase the temperature compensation accuracy of the apparatus, it is necessary to increase the measurement accuracy of the A / D converter 203 and the D / A converter 207, and the production cost is increased due to such higher accuracy. There is also.

SUMMARY OF THE INVENTION An object of the present invention is to solve many of these problems. In a sensor driving circuit, a digital compensating means is used as a temperature compensating means, and a CPU of a digital circuit is connected to an analog circuit via a digital trimmer. It is an object of the present invention to provide a sensor driving circuit with high accuracy and small circuit scale for temperature compensation of a sensor by using a hardware configuration for performing offset adjustment and gain adjustment by coupling with an operational amplifier of a circuit.

[0007]

According to the first aspect of the present invention,
In a sensor driving circuit having a temperature sensing means and having a function of compensating a temperature of a sensor based on a temperature signal from the temperature sensing means, a temperature signal from the temperature sensing means for measuring a temperature of the sensor circuit is represented by 2 A pressure sensor driving circuit comprising a digital compensating means for digitally controlling the sensor by performing digital control using a coded digital control signal.

According to the first aspect of the present invention, the control of the analog compensation amount for performing the temperature compensation based on the analog signal from the temperature sensing means is executed by the digital control using the digital compensation means. The scale of the circuit configuration can be simplified as compared with the case where the compensation of the heating means is collectively processed digitally. As a result, the number of components of the digital IC can be reduced, and a small and inexpensive sensor drive circuit can be realized. In addition, by performing digital control, the temperature of the element can be calibrated in advance, and the calibration value can be stored in the storage unit and used. As a result, the temperature of the sensor can be instantaneously compensated based on the data stored in the storage unit.

According to a second aspect of the present invention, in the sensor driving circuit having a temperature sensing means and having a function of performing temperature compensation based on a temperature signal from the temperature sensing means, the temperature sensing means for measuring the temperature of the sensor. Digital compensation means for compensating the temperature of the sensor by digitally controlling the temperature signal from the means using a binary control digital signal, wherein the digital compensation means can change the resistance value by the digital control signal. A pressure sensor drive circuit comprising a trimmer, wherein compensation of an offset value of a sensor signal amplifying means and gain adjustment are performed based on a resistance value of the digital trimmer.

According to the second aspect of the present invention, the digital compensator has a digital trimmer capable of changing the resistance value with a digital signal, so that the analog circuit and the digital circuit are simply coupled. That is, by using a digital trimmer for the offset adjusting resistor and the gain adjusting resistor of the sensor signal amplifying means, it is possible to perform temperature compensation of the amplifying means by a digital signal from the CPU. This makes it possible to adjust the offset of each amplifying unit based on the data recorded in the storage unit in advance. In addition to applying digital processing using a CPU to select and control the resistance value of the digital trimmer that does not require measurement accuracy, an analog output adjustment circuit is used for temperature compensation control for sensors that require measurement accuracy and gain and offset compensation for amplifiers. By applying the analog processing, it is possible to optimize the circuits constituting the respective signal processing systems and to reduce the size. Further, since the offset adjustment resistor and the gain adjustment resistor of the plurality of amplifying units can be configured by one digital trimmer, the offset adjustment circuit and the gain adjustment circuit conventionally required for each amplifying unit are collectively reduced to reduce the circuit scale. It has the effect of being able to be converted.

According to a third aspect of the present invention, in the sensor driving circuit according to the first or second aspect, an amplifying means for amplifying an output of the sensor and an offset adjusting resistor of the amplifying means use the digital control signal. And a control unit for adjusting to a required offset range.

According to the third aspect of the invention, the same effects as those of the first and second aspects can be obtained. In addition, amplification means is used for the analog output signal of the sensor, whereby the gain of the sensor signal for temperature compensation can be adjusted. Further, by using digital compensating means for the offset adjusting resistor of the amplifying means, temperature compensation of the amplifying means can be performed at the same time. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to a fourth aspect of the present invention, in the pressure sensor driving circuit according to any one of the first to third aspects, the pressure sensor driving circuit further includes an amplifying means for amplifying the output of the sensor, and a gain adjusting resistor of the amplifying means transmits the digital control signal. This is a pressure sensor drive circuit having a control unit for adjusting the gain to a required gain range using the control unit.

According to the fourth aspect of the invention, the same effects as those of the first to third aspects can be obtained. Further, an amplifier is used for an analog output signal of the sensor, and a gain adjusting resistor of the amplifier is used for a digital compensator, and the gain of the sensor signal for temperature compensation is adjusted by the digital means. As a result, stable measurement can be performed even with temperature changes, and a highly reliable sensor is realized.

According to a fifth aspect of the present invention, in the pressure sensor drive circuit according to any one of the first to fourth aspects, the differential means for detecting the output of the sensor in a differential mode, and the offset adjusting resistor of the differential means are connected to each other. This is a pressure sensor drive circuit having a control unit that adjusts to a required offset range using a digital control signal.

According to the fifth aspect of the present invention, the same effects as those of the first to fourth aspects can be obtained. Further, the output of the sensor is detected by using the differential means, and the offset adjusting resistor of the differential means is used by the digital compensating means, so that the temperature compensation of the differential means can be performed at the same time. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to a sixth aspect of the present invention, in the pressure sensor drive circuit according to any one of the first to fifth aspects, a differential means for detecting a sensor output in a differential mode, and a gain adjusting resistor of the differential means are provided. This is a pressure sensor drive circuit having a control unit that adjusts to a required gain range using a digital control signal.

According to the sixth aspect of the invention, the same effects as those of the first to fifth aspects can be obtained. Claim 6
According to the described invention, the output of the sensor is detected using the differential means. Further, by using a digital compensating means for the gain adjusting resistor of the amplifying means, it is possible to simultaneously perform temperature compensation of the differential means. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to a seventh aspect of the present invention, in the pressure sensor drive circuit according to any one of the first to sixth aspects, the digital control of the addition means for adding to the output of the sensor and the resistance for adjusting the offset value of the addition means are provided. This is a pressure sensor drive circuit having a control unit that adjusts to a required offset range using a signal.

According to the seventh aspect of the invention, the same effects as those of the first to sixth aspects can be obtained. The addition means is used for the analog output signal of the sensor, the offset adjustment resistance of the addition means is used for the digital compensation means, and the offset adjustment of the sensor signal for the temperature compensation is performed by the digital means. As a result, stable measurement can be performed even with temperature changes, and a highly reliable sensor is realized.

According to an eighth aspect of the present invention, in the pressure sensor driving circuit according to any one of the first to sixth aspects, an adding means for adding to the output of the sensor, and a gain adjusting resistor of the adding means, for controlling the digital control signal by This is a pressure sensor drive circuit having a control unit for adjusting the gain to a required gain range using the control unit.

According to the eighth aspect of the invention, the same effects as those of the first to seventh aspects can be obtained. Further, by using an adding means for the analog output signal of the sensor and further using a digital compensating means for the offset adjusting resistor of the adding means, it is possible to simultaneously perform temperature compensation of the adding means. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

The invention according to claim 9 is the pressure sensor drive circuit according to any one of claims 1 to 8, wherein the sensor is a semiconductor pressure sensor.

According to the ninth aspect of the present invention, the pressure sensor driving circuit according to any one of the first to eighth aspects is used for a driving circuit of a semiconductor pressure sensor. The semiconductor pressure sensor is small and has high sensitivity, but generally has a characteristic that the temperature dependency is large. In the pressure sensor drive circuit according to the first to eighth aspects, means for amplifying an analog output of a sensor having excellent sensitivity by an analog circuit is used. For temperature compensation, a digital circuit capable of high-speed automatic control is used. The digital circuit and the analog circuit are connected using a digital trimmer, and the compensating circuit is simplified. As a result, it is possible to realize a compact, high-speed automatic control and high-sensitivity pressure measurement device.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a pressure sensor drive circuit 10 according to one embodiment of the present invention. The circuit of the present embodiment includes a pressure sensor 20, a digital compensating means 30 for performing temperature compensation of the pressure sensor 20, and an analog output adjusting circuit 40 for amplifying an analog signal from the pressure sensor 20 to perform offset adjustment and gain adjustment. It is mainly configured.

The digital compensating means 30 for compensating the temperature of the pressure sensor 20 includes a temperature sensing means 3 for measuring the sensor temperature.
1. An A / D converter 32 for converting an analog signal of the temperature sensing means 31 into a digital signal, a CPU 33 for processing a digital signal and determining an adjustment resistance value for temperature compensation, and a resistance value according to a digital signal from the CPU 33. The digital trimmer 34 that changes the value is mainly configured. Further, by using the digital compensation means 30 for the temperature compensation in this way, the CPU 33 controls the temperature compensation based on the data which has been calibrated and recorded in advance. As a result, regarding the temperature compensation of the sensor 20, automatic control and high-speed processing by the CPU 33 are enabled.

The analog output adjusting circuit 40 includes a differential means 41 for detecting and amplifying an analog signal from the pressure sensor 20 in a differential mode, an amplifying means 42 for performing gain adjustment for temperature compensation of the pressure sensor 20, and an offset. The configuration is centered on an adding means 43 for performing the adjustment. Further, amplifying means 42
The digital trimmer 34 of the digital compensating means 30 is connected to the gain adjusting resistance of the
Is used, and the digital trimmer 3 by the CPU 33 is used.
The gain adjustment and the offset adjustment of the differential means 41, the amplifying means 42, and the adding means 43 are performed by the resistance adjustment of 4, and the temperature of the sensor 20 is compensated.

With this configuration, there is provided digital compensating means 30 for digitally controlling the temperature signal from the temperature sensing means 31 for measuring the temperature of the sensor 20 by using a digital control signal obtained by converting the temperature into a binary code, thereby compensating the temperature of the sensor 20. Then, the digital compensating means 30 has a digital trimmer 34 having a plurality of variable resistance parts whose resistance value can be varied by a digital control signal, and is based on the resistance value of the variable resistance part of the digital trimmer 34 individually controlled by the CPU 33. Thus, the pressure sensor driving circuit 10 performs the compensation of the offset values of the plurality of amplifying means 42 of the sensor signal and the gain adjustment in a lump.

As described above, the analog output adjusting circuit 40 is used for adjusting the output of the pressure sensor 20 and the digital control circuit which is digitally controlled by the CPU 33 and the analog output adjusting circuit 40 via the digital trimmer 34 in the digital compensating means 30. 30 for controlling the selection of the resistance value of the digital trimmer 34 which does not require measurement accuracy.
By applying the digital processing using the analog output adjustment circuit 40 to the temperature compensation control of the sensor 20 requiring the measurement accuracy, the gain compensation of the amplifier 42, and the offset compensation of the amplifier 43, while applying the digital processing using the 33, It is possible to optimize the circuits constituting the respective signal processing systems and to reduce the size. That is, by using the analog output adjustment circuit 40 for adjusting the output of the pressure sensor 20, the high sensitivity of the pressure sensor 20 is effectively used, and the compensation of the temperature sensing means 31 is digitally processed in a batch. By using an analog circuit that can configure a circuit having a large number of parts in a compact manner, the scale of the circuit configuration can be simplified. As a result, the number of components of the digital IC can be reduced, and an effect that a small and inexpensive sensor drive circuit 10 can be realized can be achieved. Further, by using the digital compensating means 30 as the temperature compensating means, automatic control and high-speed processing are enabled, and adjustment of temperature compensation is also facilitated. Further, by using the digital trimmer 34 for the connection between the digital compensation means 30 and the analog output adjustment circuit 40, it is possible to simply connect the two circuits and to reduce the cost.

As the amplifying means 42 in the analog output adjusting circuit 40, specifically, a non-inverting amplifying circuit 42 using an operational amplifier or the like is used. It can also be used to adjust to the required offset range. Further, the gain adjusting resistor of the non-inverting amplifier circuit 42 can be adjusted to a required gain range using a digital control signal. By using the digital compensating means 30 for the offset adjusting resistor of the non-inverting amplifier circuit 42, it is possible to perform the temperature compensation of the output of the pressure sensor 20 and the temperature compensation of the non-inverting amplifier circuit 42 at the same time. As a result, stable measurement can be performed even with temperature changes, and a highly reliable sensor 20 is realized.

Also, as the differential means 41 in the analog output adjustment circuit 40, a differential amplifier circuit 41 using an operational amplifier or the like is used, and an offset adjustment resistor of the differential amplifier circuit 41 is required by using a digital control signal. And the gain adjustment resistor can be further adjusted to a required gain range using a digital control signal. Using the digital trimmer 34 for the offset adjustment resistor and the gain adjustment resistor of the differential amplifier circuit 41, the digital controller 30 performs temperature compensation of the differential amplifier circuit 41. As a result, stable measurement can be performed even with respect to temperature changes, and a highly reliable sensor 20 is realized.

Further, as an adding means 43 in the analog output adjusting circuit 40, an adding circuit 43 using an operational amplifier or the like is used.
, The offset adjusting resistor of the adding circuit 43 can be adjusted to a required offset range using a digital control signal, and the gain adjusting resistor can be adjusted to a required gain range using a digital control signal. Using the digital trimmer 34 for the offset adjustment resistor and the gain adjustment resistor of the addition circuit 43, the digital control means 30 performs temperature compensation of the sensor signal and temperature compensation of the addition circuit. by this,
Stable measurement is possible even with temperature changes, and a highly reliable sensor 20 is realized.

Next, the operation of the semiconductor pressure sensor drive circuit 10 will be described as one embodiment. Typically,
The semiconductor pressure sensor 20 has the advantage of high sensitivity, but has the disadvantage of having large temperature dependence. Therefore, a temperature compensation circuit is used for the purpose of reducing such disadvantages. First, the semiconductor pressure sensor 20 is calibrated at each predetermined temperature, and the CPU 33 stores the gain adjustment resistance value and the offset adjustment resistance value of the pressure sensor 20 in a predetermined temperature range.

At the time of measuring the pressure, the temperature of the semiconductor pressure sensor 20 is measured at the same time as the pressure is measured.
31 and the analog signal from the temperature sensitive resistor 31 is A
The digital signal is converted into a binary coded digital signal by the / D converter 32. The converted signal is sent to the CPU 33, and the CPU 33 determines an offset adjustment resistance value and a gain adjustment resistance value based on data stored when temperature calibration is performed in advance. The CPU 33 sends a digital signal corresponding to the determined resistance value to the digital trimmer 34,
The resistance value of each terminal connected to the adding circuit 43 and the non-inverting amplifier circuit 42 is changed and adjusted. According to the resistance value, an addition circuit 43 is added to the analog output of the semiconductor pressure sensor 20.
, And the gain of the sensor 20 using the non-inverting amplifier circuit 42 is adjusted, and temperature compensation is performed.

As described above, the drive circuit of the present embodiment executes the control of the analog compensation amount for performing the temperature compensation based on the analog signal from the temperature-sensitive resistor 31 by the digital control using the digital compensation means 30. The temperature of the signal from the semiconductor sensor 20 is compensated by the analog output adjustment circuit 40. When precise control such as temperature compensation control is to be performed, such precise control is performed with a small and simple circuit configuration as compared with digital control by the CPU 33 which requires a large-scale circuit and a complicated program. By installing the analog output adjustment circuit 40 capable of performing the above, the configuration of the sensor drive circuit can be simplified and downsized. Also, in a sensor 20 having high sensitivity but having a large temperature dependency, such as the semiconductor pressure sensor 20, by using the drive circuit of the present embodiment, the amplification of the sensor signal and the adjustment of the analog compensation amount can be performed by the analog output adjustment circuit. 40
Therefore, the high sensitivity of the sensor 20 can be effectively used. Furthermore, the automatic and high-speed processing by the digital temperature compensation 30 by the CPU 33 improves the stability and reliability of the measurement. As a result, there is an effect that a compact, highly sensitive and highly reliable pressure measuring device can be realized.

In order to convert an analog signal from the temperature-sensitive resistor 31 into a digital signal, an A / D converter 32 is required. The analog signal from the temperature-sensitive resistor is amplified by an amplification amplifier. , Low resolution A /
The D converter 32 can be used, and the cost can be reduced. By using an A / D converter built-in type for the CPU 33, the circuit occupied by the A / D converter 32 for converting an analog signal from the temperature-sensitive resistor 31 into a digital signal can be omitted, thereby simplifying the circuit. The size and cost can be reduced. Further, by manufacturing the temperature-sensitive resistor 31 on the semiconductor pressure sensor 20, the circuit space can be simplified by similarly omitting the component space of the temperature-sensitive resistor 31, and the size and cost can be further reduced.

[0037]

According to the first aspect of the present invention, the control of the analog compensation amount for performing the temperature compensation based on the analog signal from the temperature sensing means is performed by the digital control using the digital compensation means. The scale of the circuit configuration can be simplified as compared with the case where the compensation for the temperature sensing means is collectively processed digitally. As a result, the number of components of the digital IC can be reduced, and a small and inexpensive sensor drive circuit can be realized. In addition, by performing digital control, the temperature of the element can be calibrated in advance, and the calibration value can be stored in the storage unit and used. As a result, the temperature of the sensor can be instantaneously compensated based on the data stored in the storage unit.

According to the second aspect of the present invention, the analog compensator and the digital circuit are simply coupled by providing the digital compensator with the digital trimmer whose resistance value can be varied by a digital signal. That is, by using a digital trimmer for the offset adjusting resistor and the gain adjusting resistor of the sensor signal amplifying means, it is possible to perform temperature compensation of the amplifying means by a digital signal from the CPU. This makes it possible to adjust the offset of each amplifying unit based on the data recorded in the storage unit in advance. In addition to applying digital processing using a CPU to select and control the resistance value of the digital trimmer that does not require measurement accuracy, an analog output adjustment circuit is used for temperature compensation control for sensors that require measurement accuracy and gain and offset compensation for amplifiers. By applying the analog processing, it is possible to optimize the circuits constituting the respective signal processing systems and to reduce the size. Further, since the offset adjustment resistor and the gain adjustment resistor of the plurality of amplifying units can be configured by one digital trimmer, the offset adjustment circuit and the gain adjustment circuit conventionally required for each amplifying unit are collectively reduced to reduce the circuit scale. It has the effect of being able to be converted.

According to the third aspect of the invention, the same effects as those of the first and second aspects can be obtained. In addition, amplification means is used for the analog output signal of the sensor, whereby the gain of the sensor signal for temperature compensation can be adjusted. Further, by using digital compensating means for the offset adjusting resistor of the amplifying means, temperature compensation of the amplifying means can be performed at the same time. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to the fourth aspect of the invention, the same effects as those of the first to third aspects can be obtained. Further, an amplifier is used for an analog output signal of the sensor, and a gain adjusting resistor of the amplifier is used for a digital compensator, and the gain of the sensor signal for temperature compensation is adjusted by the digital means. As a result, stable measurement can be performed even with temperature changes, and a highly reliable sensor is realized.

According to the fifth aspect of the invention, the same effects as those of the first to fourth aspects can be obtained. Further, the output of the sensor is detected by using the differential means, and the offset adjusting resistor of the differential means is used by the digital compensating means, so that the temperature compensation of the differential means can be performed at the same time. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to the sixth aspect of the invention, the same effects as those of the first to fifth aspects can be obtained. Claim 6
According to the described invention, the output of the sensor is detected using the differential means. Further, by using a digital compensating means for the gain adjusting resistor of the amplifying means, it is possible to simultaneously perform temperature compensation of the differential means. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to the seventh aspect of the invention, the same effects as those of the first to sixth aspects can be obtained. The addition means is used for the analog output signal of the sensor, the offset adjustment resistance of the addition means is used for the digital compensation means, and the offset adjustment of the sensor signal for the temperature compensation is performed by the digital means. As a result, stable measurement can be performed even with temperature changes, and a highly reliable sensor is realized.

According to the eighth aspect of the invention, the same effects as those of the first to seventh aspects can be obtained. Further, by using an adding means for the analog output signal of the sensor and further using a digital compensating means for the offset adjusting resistor of the adding means, it is possible to simultaneously perform temperature compensation of the adding means. As a result, stable measurement is possible even with temperature changes, and a highly reliable sensor is realized.

According to the ninth aspect of the present invention, the pressure sensor drive circuit according to any one of the first to eighth aspects is used for a drive circuit of a semiconductor pressure sensor. The semiconductor pressure sensor is small and has high sensitivity, but generally has a characteristic that the temperature dependency is large. In the pressure sensor drive circuit according to the first to eighth aspects, means for amplifying an analog output of a sensor having excellent sensitivity by an analog circuit is used. For temperature compensation, a digital circuit capable of high-speed automatic control is used. The digital circuit and the analog circuit are connected using a digital trimmer, and the compensating circuit is simplified. As a result, it is possible to realize a compact, high-speed automatic control and high-sensitivity pressure measurement device.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating a basic configuration of a pressure sensor drive circuit according to the present invention.

FIG. 2 is a configuration diagram of a conventional displacement measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Sensor drive circuit 20 Pressure sensor 21 Power supply 30 Digital compensation means 31 Temperature sensing means 32 A / D converter 33 CPU 34 Digital trimmer 35 Fixed resistance 40 Analog output adjustment circuit 41 Differential means 42 Amplification means 43 Addition means

Claims (9)

[Claims] 1. A sensor driving circuit having a temperature sensing means and having a function of compensating a temperature of a sensor based on a temperature signal from the temperature sensing means, wherein the temperature sensing means measures a temperature of the sensor circuit. A pressure sensor driving circuit, comprising: a digital compensating means for digitally controlling the temperature signal by using a digital control signal obtained by converting the temperature signal into a binary code to compensate for the temperature of the sensor. 2. A sensor driving circuit having temperature sensing means and having a function of performing temperature compensation based on a temperature signal from said temperature sensing means, wherein a temperature signal from said temperature sensing means for measuring a temperature of said sensor is provided. Digital compensating means for digitally controlling the sensor by performing digital control using a binary-coded digital control signal, the digital compensating means having a digital trimmer capable of changing a resistance value with a digital control signal, A pressure sensor drive circuit for compensating for an offset value of a sensor signal amplifying means and adjusting gain based on a resistance value of the digital trimmer. 3. An amplifying means for amplifying an output of a sensor, and a control unit for adjusting an offset adjusting resistor of the amplifying means to a required offset range using the digital control signal. Or a pressure sensor drive circuit according to claim 2. 4. An amplifier for amplifying the output of the sensor, and a controller for adjusting a gain adjusting resistor of the amplifier to a required gain range using the digital control signal. Item 4. The pressure sensor drive circuit according to any one of Items 1 to 3. 5. It has differential means for detecting an output of a sensor in a differential mode, and a control unit for adjusting an offset adjusting resistor of the differential means to a required offset range using the digital control signal. The pressure sensor drive circuit according to claim 1, wherein: 6. A differential unit for detecting an output of a sensor in a differential mode, and a control unit for adjusting a gain adjusting resistor of the differential unit to a required gain range using the digital control signal. The pressure sensor drive circuit according to claim 1, wherein: 7. An adder for adding to an output of a sensor, and a controller for adjusting an offset value adjusting resistor of the adder to a required offset range using the digital control signal. The pressure sensor drive circuit according to claim 1. 8. An apparatus according to claim 1, further comprising an adder for adding to the output of the sensor, and a controller for adjusting a gain adjusting resistor of the adder to a required gain range using the digital control signal. Item 8. A pressure sensor drive circuit according to any one of Items 1 to 7. 9. The pressure sensor drive circuit according to claim 1, wherein the sensor is a semiconductor pressure sensor.