Silicon piezoresistive pressure sensor linear compensation circuit and compensation method thereof

Abstract

The invention discloses a silicon piezoresistive pressure sensor linear compensation circuit and a compensation method thereof, and belongs to the technical field of silicon piezoresistive pressure sensors, the silicon piezoresistive pressure sensor linear compensation circuit comprises a signal conditioner D1, an operational amplifier N1, a pot cover curve correction switch S1, a pot bottom curve correction switch S2 and voltage division compensation resistors R1-R7, through adjustment of a pot cover curve correction switch S1, a pot bottom curve correction switch S2 and voltage division compensation resistors R1-R7, a correction excitation voltage UR is subjected to feedback adjustment along with an output voltage VOUT, the correction excitation voltage UR and the output voltage of a silicon piezoresistive pressure sensor core N2 are in a linear relation, and finally the silicon piezoresistive pressure sensor performs linear output. The rejection rate of the silicon piezoresistive pressure sensor core N2 is reduced, and the problem that in the existing linear compensation technology, single linear compensation of a pot cover curve can only be achieved through a rear-end circuit, and linear compensation of a pot bottom curve cannot be met is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon piezoresistive pressure sensors, and in particular to a silicon piezoresistive pressure sensor linear compensation circuit and a compensation method thereof. Background Art

[0002] The silicon piezoresistive pressure sensor is based on the piezoresistive effect of silicon materials, and uses a silicon piezoresistive pressure sensor core to sense the measured pressure. The silicon piezoresistive pressure sensor core adopts deep silicon etching and concentrated boron diffusion and other process methods. When the silicon diaphragm is subjected to the pressure signal, the resistance value of a pair of bridge arms of the bridge increases, and the resistance value of the other pair of bridge arms decreases accordingly, and the change in resistance value is proportional to the pressure. When the bridge supplies excitation voltage or current, it is amplified, corrected, temperature compensated, and signal converted by the conditioning circuit, and the voltage / current / digital signal is output. Silicon piezoresistive pressure sensors have the characteristics of high precision, small size, good dynamic characteristics, and easy integration, and are widely used in aviation, aerospace and other fields.

[0003] Nonlinearity is an indicator that characterizes the degree of inconsistency between the average calibration curve of the sensor and the theoretical straight line. It is determined by the sensor's sensitive element and is difficult to compensate through hardware. The nonlinearity of the silicon piezoresistive pressure sensor is determined by the silicon piezoresistive pressure sensor core. There are two types of nonlinear curves: the pot cover curve and the pot bottom curve. The nonlinearity of the silicon piezoresistive pressure sensor is generally ≤±0.2%FS. The existing linear compensation technology can only achieve single linear compensation of the pot cover curve through the back-end circuit, and cannot meet the linear compensation of the pot bottom curve. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a linear compensation circuit for a silicon piezoresistive pressure sensor and a compensation method thereof, which solves the problem that the existing linear compensation technology can only achieve single linear compensation of the pot cover curve through the back-end circuit and cannot meet the linear compensation of the pot bottom curve.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] Provided is a linear compensation circuit for a silicon piezoresistive pressure sensor, which includes a signal conditioner D1, an operational amplifier N1, a pot cover curve correction switch S1, a pot bottom curve correction switch S2, and voltage division compensation resistors R1 to R7;

[0007] The two signal input terminals of the signal conditioner D1 are respectively used to connect with the two signal output terminals of the silicon piezoresistive pressure sensor core N2, the output terminal is connected with one end of the voltage divider compensation resistor R1 to output the voltage U1, and the adjustment terminal is connected with one end of the voltage divider compensation resistor R6 to output the voltage VOUT;

[0008] The other end of the voltage-dividing compensation resistor R1 and one end of the voltage-dividing compensation resistor R3 are connected to the in-phase input end of the operational amplifier N1, and the other end of the voltage-dividing compensation resistor R3 is grounded; the voltage-dividing compensation resistor R1 is connected in series with the voltage-dividing compensation resistor R3;

[0009] The other end of the voltage-dividing compensation resistor R6 is connected in series with the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7, the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7 are connected in parallel, the other end of the voltage-dividing compensation resistor R2 is connected in parallel with the pot cover curve correction switch S1 and the pot bottom curve correction switch S2, the other end of the curve correction switch S1 is connected to the common point of the voltage-dividing compensation resistor R1 and the voltage-dividing compensation resistor R3, the other end of the pot bottom curve correction switch S2 is connected to the inverting input end of the operational amplifier N1; the other end of the voltage-dividing compensation resistor R7 is grounded and connected to one end of the voltage-dividing compensation resistor R5, the other end of the voltage-dividing compensation resistor R5 is connected to one end of the voltage-dividing compensation resistor R4 and the other end of the pot bottom curve correction switch S2, the other end of the voltage-dividing compensation resistor R4 is connected to the output end of the operational amplifier N1, the output end of the operational amplifier N1 is connected to the silicon piezoresistive pressure sensor core N2, and the output end of the operational amplifier N1 outputs the correction excitation voltage UR.

[0010] The basic principle of the linear compensation circuit of the silicon piezoresistive pressure sensor in this scheme is: the signal conditioner D1 collects the voltage signals V+ and V- output by the silicon piezoresistive pressure sensor core N2, the signal conditioner provides the voltage U1, and outputs the conditioned output voltage VOUT at the same time; the voltage U1 and the output voltage VOUT are corrected by the operational amplifier N1 and the voltage-dividing compensation resistors R1~R7 to output the corrected excitation voltage UR to power the silicon piezoresistive pressure sensor core, the corrected excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core are in a linear relationship, and the purpose of correcting the output voltage VOUT is achieved by adjusting the size of the corrected excitation voltage UR, thereby realizing linear compensation, and finally making the silicon piezoresistive pressure sensor output linearly, thereby reducing the scrap rate of the silicon piezoresistive pressure sensor core N2.

[0011] Furthermore, the resistance values ​​of the voltage-dividing compensation resistors R1 to R7 are adjustable, and multiple combinations of multiple resistors can be adjusted to increase the utilization efficiency of resistors with different resistance values ​​and reduce the dependence on the resistance values.

[0012] Furthermore, when the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited and the pot bottom correction switch S2 is disconnected, thereby realizing the correction of the pot cover curve in the nonlinearity of the silicon piezoresistive pressure sensor.

[0013] Furthermore, when the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected and the pot bottom correction switch S2 is short-circuited, thereby realizing the correction of the pot bottom curve in the nonlinearity of the silicon piezoresistive pressure sensor.

[0014] The present solution also provides a compensation method for a linear compensation circuit of a silicon piezoresistive pressure sensor, which comprises:

[0015] Step 1: Calculate the voltage U2 after the output voltage VOUT is divided. The calculation formula of voltage U2 is:

[0016]

[0017] Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited, and the pot bottom correction switch S2 is disconnected. The addition correction excitation voltage UR outputted from the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the addition correction excitation voltage UR is:

[0018]

[0019] When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected, the pot bottom correction switch S2 is short-circuited, and the output subtraction correction excitation voltage UR of the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the subtraction correction excitation voltage UR is:

[0020]

[0021] Step 3: The silicon piezoresistive pressure sensor outputs linearly, completing the linear compensation of the silicon piezoresistive pressure sensor. The beneficial effects of the present invention are:

[0022] 1. Compared with the existing linear compensation technology, the linear compensation circuit and compensation method of a silicon piezoresistive pressure sensor in this scheme adjusts the pot cover curve correction switch S1, the pot bottom curve correction switch S2 and the voltage divider compensation resistors R1~R7, so that the correction excitation voltage UR is adjusted with the output voltage VOUT, and the correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core N2 are linearly related, and finally the silicon piezoresistive pressure sensor output is linear. The pot cover curve correction switch S1 and the pot bottom curve correction switch S2 can be selected according to the output characteristics of the silicon piezoresistive pressure sensor core N2, so that the same linear compensation circuit can correct different nonlinear curves in the nonlinearity of the silicon piezoresistive pressure sensor, reduce the scrap rate of the silicon piezoresistive pressure sensor core N2, and solve the problem that the existing linear compensation technology can only realize the single linear compensation of the pot cover curve through the back-end circuit, and cannot meet the linear compensation of the pot bottom curve.

[0023] 2. In the linear compensation circuit of a silicon piezoresistive pressure sensor in this scheme, the operational amplifier N1 realizes addition and subtraction correction, and at the same time isolates the signal conditioner D1 and the silicon piezoresistive pressure sensor core N2 to reduce interference signals.

[0024] 3. A linear compensation circuit for a silicon piezoresistive pressure sensor in this scheme uses commonly used devices with low device cost. It also uses multiple combinations of multiple resistors to increase the utilization efficiency of the resistors and reduce the dependence on the resistance value of the resistors. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the nonlinearity of a silicon piezoresistive pressure sensor.

[0026] Figure 2 The figure is a schematic diagram of the principle of a linear compensation circuit for a silicon piezoresistive pressure sensor. DETAILED DESCRIPTION

[0027] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0028] like Figure 1 As shown in the figure, nonlinearity is an indicator that characterizes the degree of inconsistency between the average calibration curve of the sensor and the theoretical straight line. It is determined by the sensor's sensitive element and is difficult to compensate through hardware. The nonlinearity of the silicon piezoresistive pressure sensor is determined by the silicon piezoresistive pressure sensor core. There are two types of nonlinear curves: the pot cover curve and the pot bottom curve. The nonlinearity of the silicon piezoresistive pressure sensor is generally ≤±0.2%FS. The existing linear compensation technology can only achieve single linear compensation of the pot cover curve through the back-end circuit, and cannot meet the linear compensation of the pot bottom curve.

[0029] In order to solve the above problems, this solution provides a linear compensation circuit for a silicon piezoresistive pressure sensor, such as Figure 2 As shown, the linear compensation circuit of the silicon piezoresistive pressure sensor includes a signal conditioner D1, an operational amplifier N1, a pot cover curve correction switch S1, a pot bottom curve correction switch S2 and voltage divider compensation resistors R1 to R7.

[0030] The two signal input terminals of the signal conditioner D1 are respectively used to connect with the two signal output terminals of the silicon piezoresistive pressure sensor core N2, the output terminal is connected with one end of the voltage divider compensation resistor R1 to output the voltage U1, and the adjustment terminal is connected with one end of the voltage divider compensation resistor R6 to output the voltage VOUT;

[0031] The other end of the voltage-dividing compensation resistor R1 and one end of the voltage-dividing compensation resistor R3 are connected to the in-phase input end of the operational amplifier N1, and the other end of the voltage-dividing compensation resistor R3 is grounded; the voltage-dividing compensation resistor R1 is connected in series with the voltage-dividing compensation resistor R3;

[0032] The other end of the voltage-dividing compensation resistor R6 is connected in series with the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7, the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7 are connected in parallel, the other end of the voltage-dividing compensation resistor R2 is connected in parallel with the pot cover curve correction switch S1 and the pot bottom curve correction switch S2, the other end of the curve correction switch S1 is connected to the common point of the voltage-dividing compensation resistor R1 and the voltage-dividing compensation resistor R3, the other end of the pot bottom curve correction switch S2 is connected to the inverting input end of the operational amplifier N1; the other end of the voltage-dividing compensation resistor R7 is grounded and connected to one end of the voltage-dividing compensation resistor R5, the other end of the voltage-dividing compensation resistor R5 is connected to one end of the voltage-dividing compensation resistor R4 and the other end of the pot bottom curve correction switch S2, the other end of the voltage-dividing compensation resistor R4 is connected to the output end of the operational amplifier N1, the output end of the operational amplifier N1 is connected to the silicon piezoresistive pressure sensor core N2, and the output end of the operational amplifier N1 outputs the correction excitation voltage UR.

[0033] When the linear compensation circuit of the silicon piezoresistive pressure sensor compensates for the nonlinearity of the silicon piezoresistive pressure sensor, the signal conditioner D1 collects the voltage signals V+ and V- output by the silicon piezoresistive pressure sensor core N2, and the signal conditioner provides the voltage U1, and outputs the conditioned output voltage VOUT at the same time; the voltage U1 and the output voltage VOUT are corrected by the operational amplifier N1 and the voltage-dividing compensation resistors R1 to R7, and then the corrected excitation voltage UR is output to supply power to the silicon piezoresistive pressure sensor core. The corrected excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core are in a linear relationship. The purpose of correcting the output voltage VOUT is achieved by adjusting the magnitude of the corrected excitation voltage UR, and linear compensation is achieved, so that the silicon piezoresistive pressure sensor finally outputs linearly, and the scrap rate of the silicon piezoresistive pressure sensor core N2 is reduced. The operational amplifier N1 realizes addition and subtraction correction, and at the same time isolates the signal conditioner D1 and the silicon piezoresistive pressure sensor core N2 to reduce interference signals.

[0034] The voltage-dividing compensation resistors R1 to R7 are all commonly used devices with low device cost. The resistance values ​​of the voltage-dividing compensation resistors R1 to R7 are adjustable, and multiple combinations of multiple resistors can be adjusted to increase the utilization efficiency of resistors with different resistance values ​​and reduce dependence on the resistance values.

[0035] like Figure 1 and Figure 2 As shown, when the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited and the pot bottom correction switch S2 is disconnected, thereby realizing the correction of the pot cover curve in the nonlinearity of the silicon piezoresistive pressure sensor.

[0036] When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected and the pot bottom correction switch S2 is short-circuited, so as to realize the correction of the pot bottom curve in the nonlinearity of the silicon piezoresistive pressure sensor. By adjusting the pot cover curve correction switch S1, the pot bottom curve correction switch S2 and the voltage divider compensation resistors R1 to R7, the correction excitation voltage UR is adjusted with the output voltage VOUT, and the correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core N2 are in a linear relationship, so as to finally make the silicon piezoresistive pressure sensor output linearly. The pot cover curve correction switch S1 and the pot bottom curve correction switch S2 can be selected according to the output characteristics of the silicon piezoresistive pressure sensor core N2, so as to realize the correction of different nonlinear curves in the nonlinearity of the silicon piezoresistive pressure sensor by the same linear compensation circuit, thereby reducing the scrap rate of the silicon piezoresistive pressure sensor core N2 and solving the problem that the existing linear compensation technology can only realize the single linear compensation of the pot cover curve through the back-end circuit and cannot meet the linear compensation of the pot bottom curve.

[0037] The present solution also provides a compensation method for a linear compensation circuit of a silicon piezoresistive pressure sensor, which comprises:

[0038] Step 1: Calculate the voltage U2 after the output voltage VOUT is divided. The calculation formula of voltage U2 is:

[0039]

[0040] Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited, and the pot bottom correction switch S2 is disconnected. The addition correction excitation voltage UR outputted from the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the addition correction excitation voltage UR is:

[0041]

[0042] When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected, the pot bottom correction switch S2 is short-circuited, and the output subtraction correction excitation voltage UR of the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the subtraction correction excitation voltage UR is:

[0043]

[0044] Step 3: The silicon piezoresistive pressure sensor outputs linearly, completing the linear compensation of the silicon piezoresistive pressure sensor.

[0045] To sum up, in this scheme, a compensation method for a linear compensation circuit of a silicon piezoresistive pressure sensor is provided, which adopts a signal conditioner D1, an operational amplifier N1, a pot cover curve correction switch S1, a pot bottom curve correction switch S2 and a voltage divider compensation resistor R1~R7 to form a linear compensation circuit. The linear compensation circuit can be adjusted according to the output characteristics of the silicon piezoresistive pressure sensor core N2 to achieve the purpose of linear compensation for different curves, so that the nonlinearity of the silicon piezoresistive pressure sensor reaches ≤±0.1%FS.

Claims

1. A linear compensation circuit for a silicon piezoresistive pressure sensor, characterized in that: It includes a signal conditioner D1, an operational amplifier N1, a pot cover curve correction switch S1, a pot bottom curve correction switch S2 and voltage division compensation resistors R1 to R7; The two signal input terminals of the signal conditioner D1 are respectively used to connect with the two signal output terminals of the silicon piezoresistive pressure sensor core N2, the output terminal is connected with one end of the voltage divider compensation resistor R1 to output the voltage U1, and the adjustment terminal is connected with one end of the voltage divider compensation resistor R6 to output the voltage VOUT; The other end of the voltage-dividing compensation resistor R1 and one end of the voltage-dividing compensation resistor R3 are connected to the in-phase input end of the operational amplifier N1, and the other end of the voltage-dividing compensation resistor R3 is grounded; the voltage-dividing compensation resistor R1 is connected in series with the voltage-dividing compensation resistor R3; The other end of the voltage-dividing compensation resistor R6 is connected in series with the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7, the voltage-dividing compensation resistor R2 and the voltage-dividing compensation resistor R7 are connected in parallel, the other end of the voltage-dividing compensation resistor R2 is connected in parallel with the pot cover curve correction switch S1 and the pot bottom curve correction switch S2, the other end of the curve correction switch S1 is connected to the common point of the voltage-dividing compensation resistor R1 and the voltage-dividing compensation resistor R3, the other end of the pot bottom curve correction switch S2 is connected to the inverting input end of the operational amplifier N1; the other end of the voltage-dividing compensation resistor R7 is grounded and connected to one end of the voltage-dividing compensation resistor R5, the other end of the voltage-dividing compensation resistor R5 is connected to one end of the voltage-dividing compensation resistor R4 and the other end of the pot bottom curve correction switch S2, the other end of the voltage-dividing compensation resistor R4 is connected to the output end of the operational amplifier N1, the output end of the operational amplifier N1 is connected to the silicon piezoresistive pressure sensor core N2, and the output end of the operational amplifier N1 outputs the correction excitation voltage UR.

2. The linear compensation circuit of the silicon piezoresistive pressure sensor according to claim 1, characterized in that: The resistance values ​​of the voltage-dividing compensation resistors R1 to R7 are adjustable.

3. The linear compensation circuit of the silicon piezoresistive pressure sensor according to claim 1, characterized in that: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited and the pot bottom correction switch S2 is disconnected.

4. The linear compensation circuit of the silicon piezoresistive pressure sensor according to claim 3, characterized in that: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected and the pot bottom correction switch S2 is short-circuited.

5. A compensation method for a linear compensation circuit of a silicon piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that: include: Step 1: Calculate the voltage U2 after the output voltage VOUT is divided. The calculation formula of voltage U2 is: Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot cover curve, the pot cover correction switch S1 is short-circuited, and the pot bottom correction switch S2 is disconnected. The addition correction excitation voltage UR outputted from the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the addition correction excitation voltage UR is: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot bottom curve, the pot cover correction switch S1 is disconnected, the pot bottom correction switch S2 is short-circuited, and the output subtraction correction excitation voltage UR of the output end of the operational amplifier N1 is calculated according to the voltage U2 in step 1. The calculation formula of the subtraction correction excitation voltage UR is: Step 3: The silicon piezoresistive pressure sensor outputs linearly, completing the linear compensation of the silicon piezoresistive pressure sensor.

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