A silicon piezoresistive pressure sensor linear compensation circuit and a compensation method thereof

Abstract

This invention discloses a linear compensation circuit and method for a silicon piezoresistive pressure sensor, belonging to the technical field of silicon piezoresistive pressure sensors. The linear compensation circuit includes a signal conditioner D1, an operational amplifier N1, a lid curve correction switch S1, a bottom curve correction switch S2, and voltage divider compensation resistors R1 to R7. By adjusting the lid curve correction switch S1, the bottom curve correction switch S2, and the voltage divider compensation resistors R1 to R7, the correction excitation voltage UR is adjusted by feedback with the output voltage VOUT. The correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core N2 are linearly related, ultimately enabling the silicon piezoresistive pressure sensor to output linearly, reducing the scrap rate of the silicon piezoresistive pressure sensor core N2, and solving the problem that existing linear compensation technologies can only achieve single linear compensation of the lid curve through the back-end circuit and cannot meet the linear compensation of the bottom curve.

Description

Technical Field

[0001] This invention relates to the field of silicon piezoresistive pressure sensor technology, and in particular to a linear compensation circuit and compensation method for a silicon piezoresistive pressure sensor. Background Technology

[0002] Silicon piezoresistive pressure sensors are based on the piezoresistive effect of silicon material, using a silicon piezoresistive sensor core to sense the measured pressure. The silicon piezoresistive pressure sensor core is manufactured using deep silicon etching and concentrated boron diffusion processes. When the silicon diaphragm is subjected to a pressure signal, the resistance of one pair of bridge arms of the bridge increases, while the resistance of the other pair decreases accordingly, and the magnitude of the resistance change is proportional to the pressure. When the bridge is supplied with excitation voltage or current, the signal is amplified, corrected, temperature compensated, and converted by the conditioning circuit, outputting a voltage / current / digital signal. Silicon piezoresistive pressure sensors are characterized by high accuracy, small size, good dynamic characteristics, and ease of integration, and are widely used in aerospace and other fields.

[0003] Nonlinearity is an indicator characterizing the degree of mismatch or inconsistency between the average calibration curve of a sensor and the theoretical straight line. It is determined by the sensor's sensitive element and is difficult to compensate for through hardware. The nonlinearity of a silicon piezoresistive pressure sensor is determined by the silicon piezoresistive pressure sensor core. There are two types of nonlinearity curves: the lid curve and the bottom curve. The nonlinearity of a silicon piezoresistive pressure sensor is generally ≤±0.2%FS. Existing linear compensation techniques can only achieve single linear compensation for the lid curve through back-end circuitry and cannot meet the linear compensation requirements for the bottom curve. Summary of the Invention

[0004] To address the aforementioned shortcomings of existing technologies, this invention provides a linear compensation circuit and method for a silicon piezoresistive pressure sensor, which solves the problem that existing linear compensation technologies can only achieve single linear compensation of the pot lid curve through the back-end circuit and cannot meet the linear compensation of the pot bottom curve.

[0005] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0006] A linear compensation circuit for a silicon piezoresistive pressure sensor is provided, which includes a signal conditioner D1, an operational amplifier N1, a lid curve correction switch S1, a bottom curve correction switch S2, and voltage divider compensation resistors R1 to R7.

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

[0008] The other end of voltage divider compensation resistor R1 and one end of voltage divider compensation resistor R3 are connected to the non-inverting input terminal of operational amplifier N1, and the other end of voltage divider compensation resistor R3 is grounded; voltage divider compensation resistor R1 and voltage divider compensation resistor R3 are connected in series.

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

[0010] The basic principle of the linear compensation circuit for the silicon piezoresistive pressure sensor in this scheme is as follows: the signal conditioner D1 acquires the voltage signals V+ and V- output from the silicon piezoresistive pressure sensor core N2, the signal conditioner provides voltage U1, and simultaneously outputs the conditioned output voltage VOUT; voltage U1 and output voltage VOUT are corrected by operational amplifier N1 and voltage divider compensation resistors R1 to R7, and then output correction excitation voltage UR to power the silicon piezoresistive pressure sensor core. The correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core are linearly related. By adjusting the magnitude of the correction excitation voltage UR, the purpose of correcting the output voltage VOUT is achieved, realizing linear compensation, and ultimately making the silicon piezoresistive pressure sensor output linearly, reducing the scrap rate of the silicon piezoresistive pressure sensor core N2.

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

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

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

[0015] Step 1: Calculate the voltage U2 after dividing the output voltage VOUT. The formula for calculating voltage U2 is:

[0016]

[0017] Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot lid curve, the pot lid correction switch S1 is short-circuited, and the pot bottom correction switch S2 is open. The additive correction excitation voltage UR output from the operational amplifier N1 is calculated based on the voltage U2 from Step 1. The formula for calculating the additive correction excitation voltage UR is:

[0018]

[0019] When the output signal of the silicon piezoresistive pressure sensor core N2 is the bottom curve of the pot, the pot lid correction switch S1 is open and the pot bottom correction switch S2 is short-circuited. Based on the voltage U2 in step 1, the subtraction correction excitation voltage UR is output from the operational amplifier N1. The formula for calculating the subtraction correction excitation voltage UR is as follows:

[0020]

[0021] Step 3: The silicon piezoresistive pressure sensor outputs a linear signal, completing the linear compensation for the silicon piezoresistive pressure sensor. The beneficial effects of this invention are:

[0022] 1. Compared to existing linear compensation technologies, the linear compensation circuit and method for a silicon piezoresistive pressure sensor in this solution adjusts the lid curve correction switch S1, the bottom curve correction switch S2, and the voltage divider compensation resistors R1 to R7. This allows the correction excitation voltage UR to be adjusted in response to the output voltage VOUT, resulting in a linear relationship between the correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core N2. Ultimately, this leads to a linear output from the silicon piezoresistive pressure sensor. The lid curve correction switch S1 and the bottom curve correction switch S2 can be selected based on the output characteristics of the silicon piezoresistive pressure sensor core N2, enabling the same linear compensation circuit to correct different nonlinear curves in the nonlinearity of the silicon piezoresistive pressure sensor. This reduces the scrap rate of the silicon piezoresistive pressure sensor core N2 and solves the problem that existing linear compensation technologies can only achieve single linear compensation of the lid curve through the back-end circuit, failing to meet the linear compensation requirement for the bottom curve.

[0023] 2. In this solution, a linear compensation circuit for a silicon piezoresistive pressure sensor is provided. Operational amplifier N1 performs addition and subtraction corrections, while isolating signal conditioner D1 and silicon piezoresistive pressure sensor core N2 to reduce interference signals.

[0024] 3. The linear compensation circuit for the silicon piezoresistive pressure sensor in this solution uses common components with low cost. At the same time, it adopts multiple combinations of resistors for adjustment, which can increase the utilization efficiency of the resistors and reduce the dependence on the resistor values. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating the nonlinearity of a silicon piezoresistive pressure sensor.

[0026] Figure 2 This is a schematic diagram of a linear compensation circuit for a silicon piezoresistive pressure sensor. Detailed Implementation

[0027] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0028] like Figure 1 As shown, nonlinearity is an indicator characterizing the degree of mismatch or inconsistency between the average calibration curve of a sensor and the theoretical straight line. It is determined by the sensor's sensitive element and is difficult to compensate for through hardware. The nonlinearity of a silicon piezoresistive pressure sensor is determined by the silicon piezoresistive pressure sensor core. There are two types of nonlinearity curves: the lid curve and the bottom curve. The nonlinearity of a silicon piezoresistive pressure sensor is generally ≤±0.2%FS. Existing linear compensation techniques can only achieve single linear compensation for the lid curve through back-end circuitry and cannot meet the linear compensation requirements for the bottom curve.

[0029] To address the aforementioned issues, 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 lid curve correction switch S1, a 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 to the two signal output terminals of the silicon piezoresistive pressure sensor core N2. The output terminal is connected to one end of the voltage divider compensation resistor R1 to output voltage U1, and the adjustment terminal is connected to one end of the voltage divider compensation resistor R6 to output voltage VOUT.

[0031] The other end of voltage divider compensation resistor R1 and one end of voltage divider compensation resistor R3 are connected to the non-inverting input terminal of operational amplifier N1, and the other end of voltage divider compensation resistor R3 is grounded; voltage divider compensation resistor R1 and voltage divider compensation resistor R3 are connected in series.

[0032] The other end of the voltage divider compensation resistor R6 is connected in series with the voltage divider compensation resistors R2 and R7. The voltage divider compensation resistors R2 and R7 are connected in parallel. The other end of the voltage divider compensation resistor R2 is connected in parallel with the lid curve correction switch S1 and the bottom curve correction switch S2. The other end of the curve correction switch S1 is connected to the common point of the voltage divider compensation resistors R1 and R3. The other end of the bottom curve correction switch S2 is connected to the inverting input terminal of the operational amplifier N1. The other end of the voltage divider compensation resistor R7 is connected to ground and to one end of the voltage divider compensation resistor R5. The other end of the voltage divider compensation resistor R5 is connected to one end of the voltage divider compensation resistor R4 and the other end of the bottom curve correction switch S2. The other end of the voltage divider compensation resistor R4 is connected to the output terminal of the operational amplifier N1. The output terminal of the operational amplifier N1 is connected to the silicon piezoresistive pressure sensor core N2. The output terminal 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 acquires the voltage signals V+ and V- output from the silicon piezoresistive pressure sensor core N2. The signal conditioner provides voltage U1 and simultaneously outputs the conditioned output voltage VOUT. Voltage U1 and output voltage VOUT are corrected by operational amplifier N1 and voltage divider compensation resistors R1-R7, resulting in a correction excitation voltage UR that powers the silicon piezoresistive pressure sensor core. The correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core are linearly related. By adjusting the magnitude of the correction excitation voltage UR, the output voltage VOUT is corrected, achieving linear compensation and ultimately enabling the silicon piezoresistive pressure sensor to output linearly, reducing the scrap rate of the silicon piezoresistive pressure sensor core N2. Operational amplifier N1 performs addition and subtraction corrections and simultaneously isolates the signal conditioner D1 and the silicon piezoresistive pressure sensor core N2 to reduce interference signals.

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

[0035] like Figure 1 and Figure 2 As shown, when the output signal of the silicon piezoresistive pressure sensor core N2 is a pot lid curve, the pot lid correction switch S1 is short-circuited and the pot bottom correction switch S2 is open, thereby correcting the pot lid 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 lid correction switch S1 is open and the pot bottom correction switch S2 is short-circuited, thereby correcting the pot bottom curve in the nonlinearity of the silicon piezoresistive pressure sensor. By adjusting the pot lid 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 according to the output voltage VOUT. The correction excitation voltage UR and the output voltage of the silicon piezoresistive pressure sensor core N2 are linearly related, ultimately making the silicon piezoresistive pressure sensor output linearly. The pot lid 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, reducing the scrap rate of the silicon piezoresistive pressure sensor core N2 and solving the problem that the existing linear compensation technology can only achieve single linear compensation of the pot lid curve through the back-end circuit and cannot meet the linear compensation of the pot bottom curve.

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

[0038] Step 1: Calculate the voltage U2 after dividing the output voltage VOUT. The formula for calculating voltage U2 is:

[0039]

[0040] Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot lid curve, the pot lid correction switch S1 is short-circuited, and the pot bottom correction switch S2 is open. The additive correction excitation voltage UR output from the operational amplifier N1 is calculated based on the voltage U2 from Step 1. The formula for calculating the additive correction excitation voltage UR is:

[0041]

[0042] When the output signal of the silicon piezoresistive pressure sensor core N2 is the bottom curve of the pot, the pot lid correction switch S1 is open and the pot bottom correction switch S2 is short-circuited. Based on the voltage U2 in step 1, the subtraction correction excitation voltage UR is output from the operational amplifier N1. The formula for calculating the subtraction correction excitation voltage UR is as follows:

[0043]

[0044] Step 3: The silicon piezoresistive pressure sensor outputs a linear signal, completing the linear compensation for the silicon piezoresistive pressure sensor.

[0045] In summary, the compensation method for the linear compensation circuit of the silicon piezoresistive pressure sensor in this solution uses a combination of signal conditioner D1, operational amplifier N1, lid curve correction switch S1, bottom curve correction switch S2, and voltage divider compensation resistors R1 to 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, Includes signal conditioner D1, operational amplifier N1, lid curve correction switch S1, bottom curve correction switch S2, and voltage divider compensation resistors R1 to R7; The two signal input terminals of the signal conditioner D1 are respectively used to connect to the two signal output terminals of the silicon piezoresistive pressure sensor core N2. The output terminal is connected to one end of the voltage divider compensation resistor R1 to output voltage U1, and the adjustment terminal is connected to one end of the voltage divider compensation resistor R6 to output voltage VOUT. The other end of voltage divider compensation resistor R1 and one end of voltage divider compensation resistor R3 are connected to the non-inverting input terminal of operational amplifier N1, and the other end of voltage divider compensation resistor R3 is grounded; voltage divider compensation resistor R1 and voltage divider compensation resistor R3 are connected in series. The other end of the voltage divider compensation resistor R6 is connected in series with the voltage divider compensation resistors R2 and R7. The voltage divider compensation resistors R2 and R7 are connected in parallel. The other end of the voltage divider compensation resistor R2 is connected in parallel with the lid curve correction switch S1 and the bottom curve correction switch S2. The other end of the curve correction switch S1 is connected to the common point of the voltage divider compensation resistors R1 and R3. The other end of the bottom curve correction switch S2 is connected to the inverting input terminal of the operational amplifier N1. The other end of the voltage divider compensation resistor R7 is connected to ground and to one end of the voltage divider compensation resistor R5. The other end of the voltage divider compensation resistor R5 is connected to one end of the voltage divider compensation resistor R4 and the other end of the bottom curve correction switch S2. The other end of the voltage divider compensation resistor R4 is connected to the output terminal of the operational amplifier N1. The output terminal of the operational amplifier N1 is connected to the silicon piezoresistive pressure sensor core N2. The output terminal of the operational amplifier N1 outputs the correction excitation voltage UR.

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

3. The linear compensation circuit for 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 lid curve, the pot lid curve correction switch S1 is short-circuited and the pot bottom curve correction switch S2 is open.

4. The linear compensation circuit for 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 the bottom curve of the pot, the pot lid curve correction switch S1 is disconnected and the pot bottom curve correction switch S2 is short-circuited.

5. A compensation method for the linear compensation circuit of the silicon piezoresistive pressure sensor according to any one of claims 1 to 4, characterized in that, include: Step 1: Calculate the voltage U2 after dividing the output voltage VOUT. The formula for calculating voltage U2 is: ； Step 2: When the output signal of the silicon piezoresistive pressure sensor core N2 is a pot lid curve, the pot lid curve correction switch S1 is short-circuited, and the pot bottom curve correction switch S2 is open. The additive correction excitation voltage UR output from the operational amplifier N1 is calculated based on the voltage U2 in Step 1. The formula for calculating the additive correction excitation voltage UR is: When the output signal of the silicon piezoresistive pressure sensor core N2 is the bottom curve of the pot, the pot lid curve correction switch S1 is open and the pot bottom curve correction switch S2 is short-circuited. Based on the voltage U2 in step 1, the subtraction correction excitation voltage UR is output from the operational amplifier N1. The formula for calculating the subtraction correction excitation voltage UR is as follows: ； Step 3: The silicon piezoresistive pressure sensor outputs a linear signal, completing the linear compensation for the silicon piezoresistive pressure sensor.

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