A method, device and system for calibrating the offset voltage of an operational amplifier circuit

Abstract

The application discloses a kind of operating amplifier circuit offset voltage calibration method, device, system and computer readable storage medium, compensation circuit is constituted by current calibration circuit and resistance calibration circuit, after determining the voltage to be compensated according to the difference of actual offset voltage and the allowable offset voltage of the amplifying circuit to be compensated, the size and polarity of the voltage to be compensated are used to determine the size and direction of the unit compensation current of the variable current source in the current calibration circuit of compensation circuit, the access resistance of the resistance calibration circuit of compensation circuit is determined according to unit compensation current and the voltage to be compensated, from two angles of access resistance and the current flowing through access resistance, it is adjusted, compared with the binary current compensation scheme of traditional only using voltage dividing resistance adjustment, calibration means is more flexible, the number of required voltage dividing resistance is significantly reduced, i.e. under the same compensation accuracy, the compensation circuit area is reduced, higher compensation accuracy can be obtained, and the linearity of offset voltage calibration is improved.

Description

Technical Field

[0001] This application relates to the field of integrated circuit chip design, and in particular to a method, apparatus, system, and computer-readable storage medium for calibrating the offset voltage of an operational amplifier circuit. Background Technology

[0002] In signal chain processing circuits, the first-stage fixed-gain operational amplifier / instrumentation amplifier often causes gain errors in the final output stage due to offset voltage. This first-stage offset voltage is generally caused by mismatch in the operational amplifier itself or by mismatch in the resistor / capacitor ratio of the feedback loop. While the operational amplifier's own mismatch can be eliminated to within the required specifications using Chopper technology or Correlated Double Sampling (CDS) technology, the resistor / capacitor ratio mismatch is mainly caused by process variations and cannot be eliminated by inherent techniques; it can only be reduced through trimming.

[0003] The traditional method for adjusting the resistance / capacitor ratio mismatch of an operational amplifier is a binary current compensation scheme. This involves using a compensation circuit composed of voltage divider resistors to adjust the resistance / capacitor ratio mismatch. To achieve the required compensation accuracy, a large number of voltage divider resistors are needed, resulting in a large circuit area. Therefore, a trade-off must be made between compensation accuracy and area, which limits the compensation accuracy. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, system, and computer-readable storage medium for calibrating the offset voltage of an operational amplifier circuit, which saves the area occupied by compensation circuits that adjust the ratio mismatch of resistor / capacitor values ​​in the operational amplifier and improves the linearity of offset voltage calibration.

[0005] To address the aforementioned technical problems, this application provides a method for calibrating the offset voltage of an operational amplifier circuit, comprising:

[0006] Obtain the actual offset voltage of the amplifier circuit to be compensated;

[0007] The voltage to be compensated is determined based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated.

[0008] The magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit is determined according to the magnitude of the voltage to be compensated, and the direction of the unit compensation current is determined according to the polarity of the voltage to be compensated.

[0009] The connection resistance of the resistance calibration circuit of the compensation circuit is determined based on the unit compensation current and the voltage to be compensated.

[0010] The circuit state of the compensation circuit is adjusted according to the unit compensation current and the access resistor;

[0011] The first terminal of the resistor calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, the second terminal of the resistor calibration circuit is connected to the negative output terminal of the target amplifier, and the current calibration circuit is used to provide the unit compensation current to the resistor calibration circuit.

[0012] Optionally, the resistance calibration circuit specifically includes: X compensation resistors with the same resistance value, X+1 first switches, and X+1 second switches; the current calibration circuit specifically includes: a first variable current source and a second variable current source.

[0013] In this circuit, each of the compensation resistors is connected in series between the first terminal and the second terminal of the resistance calibration circuit. The first terminal of each of the first switches is connected to the first terminal of the first variable current source. The second terminal of each of the first switches is connected to the connection point between the first terminal of the resistance calibration circuit, the second terminal of the resistance calibration circuit, and each of the compensation resistors. The first terminal of each of the second switches is connected to the first terminal of the second variable current source. The second terminal of each of the second switches is connected to the connection point between the first terminal of the resistance calibration circuit, the second terminal of the resistance calibration circuit, and each of the compensation resistors.

[0014] Where X is a positive integer.

[0015] Optionally, determining the compensation voltage based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated specifically includes:

[0016] Make the voltage at the positive input terminal, the voltage at the negative input terminal, the common-mode input voltage, and the common-mode output voltage of the target operational amplifier equal. Connect the positive output terminal and the negative output terminal of the target operational amplifier to the input terminal of the modulator, respectively. The difference between the output codeword of the modulator and the center codeword of the modulator at this time is the residual mismatch codeword of the target operational amplifier.

[0017] Make the voltage at the positive input terminal, the voltage at the negative input terminal, and the common-mode input voltage of the target operational amplifier equal. Connect the positive and negative output terminals of the target operational amplifier to the input terminals of the modulator, respectively. Make the common-mode input voltage of the target operational amplifier equal to the lower limit of the common-mode input voltage range. Denote the difference between the output codeword and the center codeword of the modulator at this time as the lower limit of the output variable. Make the common-mode input voltage of the target operational amplifier equal to the upper limit of the common-mode input voltage range. Denote the difference between the output codeword and the center codeword of the modulator at this time as the upper limit of the output variable. Calculate the difference between the upper and lower limits of the common-mode input voltage range to obtain a first difference value. Calculate the difference between the upper and lower limits of the output variable to obtain a second difference value. Denote the ratio of the second difference value to the first difference value as the resistance mismatch codeword ratio of the amplifier circuit to be compensated.

[0018] The resistance mismatch codeword of the amplifier circuit to be compensated is calculated based on the resistance mismatch codeword ratio, the actual common-mode input voltage of the target operational amplifier, and the actual common-mode output voltage of the target operational amplifier.

[0019] The residual mismatch codeword and the resistance mismatch codeword are superimposed to obtain the adjustment codeword corresponding to the voltage to be compensated.

[0020] The center codeword is the output codeword of the modulator when the offset voltage is zero.

[0021] Optionally, determining the connection resistance of the resistance calibration circuit of the compensation circuit based on the unit compensation current and the voltage to be compensated specifically includes:

[0022] After controlling the variable current source to output the unit compensation current, the control code of the resistance calibration circuit when the minimum compensation error is corresponding to the resistance calibration circuit is scanned and determined, and recorded as the initialization code of the decoder;

[0023] The residual mismatch codeword and the initialization codeword are scaled proportionally by calculation using digital circuitry to obtain the codeword ratio of the least significant bit of the modulator corresponding to the codeword of the decoder.

[0024] The quotient of the adjustment codeword divided by the codeword ratio is the control codeword of the decoder for the resistor calibration circuit.

[0025] Optionally, determining the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit based on the magnitude of the voltage to be compensated specifically involves:

[0026] Under the premise of satisfying the magnitude of the voltage to be compensated, select the smallest unit compensation current that the variable current source can provide.

[0027] Optionally, determining the direction of the unit compensation current based on the polarity of the voltage to be compensated specifically involves:

[0028] The direction of the unit compensation current is determined based on the relationship between the voltage at the positive output terminal and the voltage at the negative output terminal of the target operational amplifier.

[0029] Optional, also includes:

[0030] Based on the actual parameters of each operational amplifier in the amplifier circuit to be compensated, the operational amplifier with the smallest offset voltage after being connected to the compensation circuit under a preset test environment is determined as the target operational amplifier.

[0031] To address the aforementioned technical problems, this application also provides a calibration device for the offset voltage of an operational amplifier circuit, comprising:

[0032] The acquisition unit is used to acquire the actual offset voltage of the amplifier circuit to be compensated.

[0033] The first calculation unit is used to determine the voltage to be compensated based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated.

[0034] The second calculation unit is used to determine the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit according to the magnitude of the voltage to be compensated, and to determine the direction of the unit compensation current according to the polarity of the voltage to be compensated.

[0035] The third calculation unit is used to determine the access resistance of the resistance calibration circuit of the compensation circuit based on the unit compensation current and the voltage to be compensated.

[0036] A control unit is used to adjust the circuit state of the compensation circuit according to the unit compensation current and the access resistance;

[0037] The first terminal of the resistor calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, the second terminal of the resistor calibration circuit is connected to the negative output terminal of the target amplifier, and the current calibration circuit is used to provide the unit compensation current to the resistor calibration circuit.

[0038] To address the aforementioned technical problems, this application also provides a calibration system for the offset voltage of an operational amplifier circuit, comprising a compensation circuit, a measurement circuit, and a controller;

[0039] The compensation circuit includes a current calibration circuit and a resistance calibration circuit. The first terminal of the resistance calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, and the second terminal of the resistance calibration circuit is connected to the negative output terminal of the target amplifier. The current calibration circuit is used to provide a unit compensation current to the resistance calibration circuit.

[0040] The measuring circuit is used to obtain the circuit parameters of the amplifier circuit to be compensated;

[0041] The controller is connected to the measurement circuit and the compensation circuit respectively, and is used to perform the steps of the operational amplifier circuit offset voltage calibration method as described in any of the above.

[0042] To address the aforementioned technical problems, this application also provides a computer-readable storage medium storing a computer program thereon, wherein the computer program, when executed by a processor, implements the steps of the calibration method for the offset voltage of the operational amplifier circuit as described in any of the preceding claims.

[0043] The operational amplifier circuit offset voltage calibration method provided in this application comprises a compensation circuit consisting of a current calibration circuit and a resistor calibration circuit. After obtaining the actual offset voltage of the amplifier circuit to be compensated, the voltage to be compensated is determined based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated. Then, the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit is determined based on the magnitude of the voltage to be compensated. The direction of the unit compensation current is determined based on the polarity of the voltage to be compensated. The connection resistor of the resistor calibration circuit of the compensation circuit is determined based on the unit compensation current and the voltage to be compensated. Adjustment is performed from two perspectives: the connection resistor and the current flowing through the connection resistor. Compared with the traditional binary current compensation scheme that only uses voltage divider resistors for adjustment, the calibration method is more flexible and significantly reduces the number of voltage divider resistors required. Thus, the area occupied by the compensation circuit is reduced while maintaining the same compensation accuracy, thereby achieving higher compensation accuracy and improving the linearity of offset voltage calibration.

[0044] This application also provides a calibration device, system, and computer-readable storage medium for the offset voltage of an operational amplifier circuit, which have the aforementioned beneficial effects, and will not be elaborated further here. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1A circuit diagram of a compensation circuit provided in an embodiment of this application;

[0047] Figure 2 This is a simplified circuit diagram without calibration.

[0048] Figure 3 A simplified circuit diagram after calibration;

[0049] Figure 4 A flowchart illustrating a method for calibrating the offset voltage of an operational amplifier circuit, provided as an embodiment of this application;

[0050] Figure 5 A flowchart illustrating a method for calibrating the offset voltage of an operational amplifier circuit, provided in an embodiment of this application.

[0051] Figure 6 A circuit block diagram illustrating the logical judgment of a calibration method for the offset voltage of an operational amplifier circuit provided in this application embodiment;

[0052] Figure 7 An overall offset voltage calibration distribution diagram provided for an embodiment of this application;

[0053] Figure 8 A schematic diagram of the compensation circuit control for a calibration method of offset voltage of an operational amplifier circuit provided in an embodiment of this application;

[0054] Figure 9 A schematic diagram of a calibration device for the offset voltage of an operational amplifier circuit provided in an embodiment of this application;

[0055] Figure 10 A schematic diagram of a calibration system for the offset voltage of an operational amplifier circuit provided in this application embodiment;

[0056] Figure 11 This is a schematic diagram of a calibration device for the offset voltage of an operational amplifier circuit, provided in an embodiment of this application. Detailed Implementation

[0057] The core of this application is to provide a method, apparatus, system, and computer-readable storage medium for calibrating the offset voltage of an operational amplifier circuit, which saves the area occupied by the compensation circuit for adjusting the ratio mismatch of the resistor / capacitor values ​​of the operational amplifier and improves the linearity of the offset voltage calibration.

[0058] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0059] Example 1

[0060] Figure 1 A circuit diagram of a compensation circuit provided in an embodiment of this application; Figure 2 This is a simplified circuit diagram without calibration. Figure 3 A simplified circuit diagram after calibration; Figure 4 This is a flowchart illustrating a method for calibrating the offset voltage of an operational amplifier circuit, as provided in an embodiment of this application.

[0061] In the operational amplifier circuit offset voltage calibration method provided in this application embodiment, the compensation circuit includes a current calibration circuit and a resistance calibration circuit. The first terminal of the resistance calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, and the second terminal of the resistance calibration circuit is connected to the negative output terminal of the target amplifier. The current calibration circuit provides a unit compensation current to the resistance calibration circuit. The current calibration circuit performs calibration through current compensation, determining the highest accuracy of the compensation technique. The resistance calibration circuit selects different connection methods for the calibration current, resulting in different equivalent resistance calibration results.

[0062] Optionally, the compensation circuit can be as follows: Figure 1 As shown, the resistance calibration circuit specifically includes: X compensation resistors with the same resistance value, X+1 first switches, and X+1 second switches; the current calibration circuit specifically includes: a first variable current source and a second variable current source.

[0063] In this circuit, each compensation resistor is connected in series between the first terminal and the second terminal of the resistance calibration circuit. The first terminal of each first switch is connected to the first terminal of the first variable current source. The second terminal of each first switch is connected to the connection point between the first terminal of the resistance calibration circuit, the second terminal of the resistance calibration circuit, and each compensation resistor. The first terminal of each second switch is connected to the first terminal of the second variable current source. The second terminal of each second switch is connected to the connection point between the first terminal of the resistance calibration circuit, the second terminal of the resistance calibration circuit, and each compensation resistor.

[0064] Where X is a positive integer.

[0065] like Figure 1 As shown, from resistors R1 to R X Switch K 11 ~K1(X+1) Switch K 21 ~K 2(X+1) To form a resistor calibration circuit, switch K 11 ~K 1(X+1) Switch K 21 ~K 2(X+1) Used to control the connection status of each resistor; a current calibration circuit is formed by current sources I1 and I2. It should be noted that... Figure 1 This is merely one connection method for the compensation circuit provided in the embodiments of this application, and does not imply that the calibration method for the offset voltage of the operational amplifier circuit provided in the embodiments of this application must be based on this compensation circuit.

[0066] Figure 1 The compensation circuit shown has the advantage of being easy to control via encoding and enabling bidirectional offset voltage regulation. In practical applications, other resistance regulation methods can also be used.

[0067] Based on the above compensation circuit, the calibration principle of the operational amplifier circuit offset voltage calibration method provided in this application embodiment is as follows:

[0068] Before calibration, the resistance is R0, and the current through the resistor is I0. The simplified circuit is as follows: Figure 2 As shown;

[0069] After calibration, the equivalent resistance is (I0 + ΔI) * R0 / I0, where ΔI is the value of the current compensation. It can be seen that the equivalent resistance change is ΔI * R0 / I0. Bidirectional calibration can be performed by adjusting the direction of the compensation current. The simplified equivalent circuit is as follows: Figure 3 As shown.

[0070] Then as Figure 4 As shown, the calibration method for the offset voltage of the operational amplifier circuit provided in this application includes:

[0071] S401: Obtain the actual offset voltage of the amplifier circuit to be compensated.

[0072] S402: Determine the voltage to be compensated based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated.

[0073] S403: Determine the magnitude of the unit compensation current of the variable current source in the current calibration circuit according to the magnitude of the voltage to be compensated, and determine the direction of the unit compensation current according to the polarity of the voltage to be compensated.

[0074] S404: Determine the resistance of the compensation circuit and the connection resistance of the calibration circuit based on the unit compensation current and the voltage to be compensated.

[0075] S405: Adjust the circuit state of the compensation circuit according to the unit compensation current and the connected resistance.

[0076] In specific implementation, for step S401, the input terminal of the target operational amplifier is short-circuited to a fixed input common-mode voltage, and the output voltage change of the target operational amplifier is observed. If there is a mismatch in the resistor value, it will cause the corresponding resistor ratio mismatch, and finally the output terminal of the target operational amplifier will show an output offset voltage.

[0077] Step S402 involves quantizing the offset direction of the output offset voltage of the target operational amplifier to determine whether it is a positive or negative offset.

[0078] For step S403, the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit is determined according to the magnitude of the voltage to be compensated. Specifically, under the premise of meeting the magnitude of the voltage to be compensated, the smallest unit compensation current that the variable current source can provide is selected. When the accuracy error index requirement is high and the compensation range is sufficient, the highest accuracy, i.e., the smallest current step size, is selected; when the highest accuracy cannot meet the overall compensation range, the minimum step size is increased until the accuracy error index can be met.

[0079] The direction of the unit compensation current can be determined based on the polarity of the voltage to be compensated. Specifically, this can be achieved by determining the direction of the unit compensation current after considering the relationship between the voltages at the positive and negative output terminals of the target operational amplifier. Alternatively, the direction of the unit compensation current can be determined by calculating the difference between the voltages at the positive and negative output terminals of the target operational amplifier and then using the sign of the difference to determine the direction of the unit compensation current.

[0080] After determining the magnitude and direction of the unit compensation current, step S404 involves quantifying the specific resistance offset.

[0081] For step S405, after the amplifier circuit to be compensated is built and before leaving the factory, the target operational amplifier to be compensated is selected, and the compensation circuit is connected between the positive input terminal and the negative output terminal of the target operational amplifier. The circuit state of the compensation circuit is controlled by the unit compensation current and the access resistor of the resistance calibration circuit determined in steps S403 and S404, so as to compensate for the offset voltage caused by the ratio mismatch of resistance value / capacitor value in the amplifier circuit to be compensated.

[0082] The operational amplifier circuit offset voltage calibration method provided in this application embodiment comprises a compensation circuit consisting of a current calibration circuit and a resistor calibration circuit. After obtaining the actual offset voltage of the amplifier circuit to be compensated, the voltage to be compensated is determined based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated. Then, the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit is determined based on the magnitude of the voltage to be compensated. The direction of the unit compensation current is determined based on the polarity of the voltage to be compensated. The connection resistance of the resistor calibration circuit of the compensation circuit is determined based on the unit compensation current and the voltage to be compensated. Adjustment is performed from two perspectives: the connection resistance and the current flowing through the connection resistance. Compared with the traditional binary current compensation scheme that only uses voltage divider resistors for adjustment, the calibration method is more flexible and significantly reduces the number of voltage divider resistors required. Thus, the area occupied by the compensation circuit is reduced while maintaining the same compensation accuracy, thereby achieving higher compensation accuracy and improving the linearity of offset voltage calibration.

[0083] Example 2

[0084] Depending on the gain requirements, the amplifier circuit to be compensated typically consists of multiple operational amplifiers. Connecting the compensation circuit to different operational amplifiers will produce different compensation effects. Therefore, based on the above embodiments, the calibration method for the offset voltage of the operational amplifier circuit provided in this application further includes:

[0085] Based on the actual parameters of each operational amplifier in the amplifier circuit to be compensated, the operational amplifier with the smallest offset voltage after being compensated by connecting the compensation circuit under the preset test environment is determined as the target operational amplifier.

[0086] In practical implementation, specific parameters may include: input common-mode voltage, input common-mode range, output common-mode voltage, output common-mode range, resistance ratio, etc. Specifically, after determining the circuit state of the compensation circuit, the calibration effect on the offset voltage can be tested under multiple preset test environments when the compensation circuit is connected to each operational amplifier. These preset test environments may include high-temperature environments, low-temperature environments, high-voltage environments, and low-voltage environments.

[0087] The average value of the offset voltage after calibration under multiple preset test conditions corresponding to an operational amplifier connected to a compensation circuit is used as the compensated offset voltage of the operational amplifier.

[0088] The operational amplifier with the smallest offset voltage after compensation is selected as the target operational amplifier for the final connection of the compensation circuit.

[0089] Example 3

[0090] Figure 5 A flowchart illustrating a method for calibrating the offset voltage of an operational amplifier circuit, provided in an embodiment of this application. Figure 6A circuit block diagram illustrating the logical judgment of a calibration method for the offset voltage of an operational amplifier circuit provided in this application embodiment; Figure 7 An overall offset voltage calibration distribution diagram provided for an embodiment of this application; Figure 8 This is a schematic diagram of the compensation circuit control for a calibration method of offset voltage of an operational amplifier circuit provided in an embodiment of this application.

[0091] Based on the above embodiments, this application provides a calibration method for the offset voltage of an operational amplifier circuit suitable for practical applications. For example... Figure 5 As shown, to facilitate batch processing of offset voltage problems, a control algorithm is pre-written to iteratively calculate the control code Minstep_Trim for the unit compensation current provided by the current calibration circuit and the control code for the access resistor of the resistance calibration circuit (specifically, the control code for switch K) based on the offset voltage. 11 ~K 1(X+1) and K 21 ~K 2(X+1) The control codes Offsetp_Trim and Offsetn_Trim are used to control the unit compensation current (Compensation Current Selection) provided by the current calibration circuit based on the control code Minstep_Trim for the unit compensation current. The control codes Offsetp_Trim and Offsetn_Trim for the connected resistor are used to perform linear quantization of resistor mismatch compensation and determine the compensation position (i.e., the process of selecting the target operational amplifier proposed in Embodiment 2 of this application). After adjustment, the offset voltage is input into the target operational amplifier to obtain the adjusted offset voltage. Then, the process returns to the step of calculating the control code based on the offset voltage, realizing iterative calculation until a control code that meets the iterative objective is obtained. The iterative objective can be set to reduce the offset voltage of the target operational amplifier to below the allowable offset voltage.

[0092] In high-precision manufacturing processes, the resistance mismatch of high-precision resistors (such as thin-film resistors) is on the order of one ten-thousandth, resulting in excellent resistance consistency and minimal voltage offset error. In contrast, the resistance mismatch of ordinary resistors is on the order of one-thousandth to one-hundredth, leading to poorer resistance consistency and a larger offset error. It is understandable that, in practice, different amplifier circuits composed of resistors of different precisions typically correspond to different control codes. Furthermore, amplifier circuits using resistors of the same precision and with the same connection method may exhibit different offset voltages due to probabilistic issues arising from differences in manufacturing processes and varying operating environments. Therefore, it is understandable that the control algorithm should be initialized according to the type of amplifier circuit before determining the control code for a specific amplifier circuit to be compensated.

[0093] In the calibration method for the offset voltage of the operational amplifier circuit provided in this application embodiment, step S402: determining the voltage to be compensated based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated, specifically includes:

[0094] Make the voltage at the positive input terminal, the voltage at the negative input terminal, the common-mode input voltage, and the common-mode output voltage of the target operational amplifier equal. Connect the positive output terminal and the negative output terminal of the target operational amplifier to the input terminal of the modulator respectively. The difference between the output codeword of the modulator and the center codeword of the modulator at this time is the residual mismatch codeword of the target operational amplifier.

[0095] Make the voltage at the positive input terminal, the voltage at the negative input terminal, and the common-mode input voltage of the target operational amplifier equal. Connect the positive and negative output terminals of the target operational amplifier to the input terminals of the modulator, respectively. Make the common-mode input voltage of the target operational amplifier equal to the lower limit of the common-mode input voltage range. Let the difference between the output codeword and the center codeword of the modulator at this time be the lower limit of the output variable. Make the common-mode input voltage of the target operational amplifier equal to the upper limit of the common-mode input voltage range. Let the difference between the output codeword and the center codeword of the modulator at this time be the upper limit of the output variable. Calculate the first difference by subtracting the upper and lower limits of the common-mode input voltage range. Calculate the second difference by subtracting the upper and lower limits of the output variable. Let the ratio of the second difference to the first difference be the resistance mismatch codeword ratio of the amplifier circuit to be compensated.

[0096] The resistance mismatch codeword of the amplifier circuit to be compensated is calculated based on the resistance mismatch codeword ratio, the actual common-mode input voltage of the target operational amplifier, and the actual common-mode output voltage of the target operational amplifier.

[0097] The residual mismatch codeword and the resistance mismatch codeword are superimposed to obtain the adjustment codeword corresponding to the voltage to be compensated.

[0098] The center codeword is the output codeword of the modulator when the offset voltage is zero.

[0099] Overall offset voltage calibration distribution as follows Figure 7 As shown, where Amp offset is the current compensation target. Then, as... Figure 6As shown, the modulator calculates the residual current compensation calibration amount Amp Residual OffsetCalibration and the resistance mismatch self-calibration amount Res Mismatch Self Calibration for the current compensation target. The decoder then decodes these values ​​to obtain the control codes Offsetp_Trim and Offsetn_Trim for the resistance calibration circuit in the compensation circuit and the current control code Minstep_Trim for the current calibration circuit.

[0100] In practice, the modulator is first initialized. For example... Figure 6 As shown, make the voltages VINP, VINN, VCM_IN, and VCM_OUT of the target operational amplifier equal. Connect the positive and negative outputs VOUTP and VOUTN of the target operational amplifier to the inputs of the modulator. If the offset voltage is zero, the output codeword of the modulator should be the center codeword. Therefore, the difference between the output codeword and the center codeword of the modulator is recorded as the residual mismatch codeword N of the target operational amplifier. Store the residual mismatch codeword N in the register.

[0101] like Figure 8 As shown, if the following is adopted Figure 1 The compensation circuit shown has a center codeword of 100....00.

[0102] It should be noted that in practical applications, after compensating for the operational amplifier's own mismatch using Chopper technology or Correlated Double Sampling (CDS) technology, the operational amplifier circuit offset voltage calibration method provided in this application embodiment can be executed. In this case, the residual mismatch problem of the operational amplifier is compensated and controlled through the residual mismatch codeword N. Figure 6 The current residual compensation calibration amount shown is Amp Residual OffsetCalibration.

[0103] Specifically, the voltages VINP, VINN, and VCM_IN at the positive and negative input terminals of the target operational amplifier are made equal. The positive and negative output terminals VOUTP and VOUTN of the target operational amplifier are connected to the input terminals of the modulator, respectively. VCM_IN is set to the upper and lower limits of the common-mode input voltage range of the operational amplifier circuit to be compensated. The register records the differences between the output codeword and the center codeword of the modulator, Code_min and Code_max, respectively. At this time, the input variable range is (VCM_min-VCM_OUT, VCM_max-VCM_OUT), and the output variable range is (Code_min, Code_max). The linear ratio of the control codeword offset output by the modulator to the common-mode input voltage VCM_IN of the target operational amplifier is (Code_min-Code_max) / (VCM_min-VCM_max), which is the resistance mismatch codeword ratio of the amplifier circuit to be compensated. This is used to approximately linearly quantify the output control codeword caused by resistance mismatch.

[0104] After completing the above initialization settings for the modulator, once the amplifier circuit to be compensated enters normal operating mode, connect VCM_IN and VCM_OUT to the modulator. The modulator performs real-time calculations based on the input VCM_IN and VCM_OUT information, substituting the aforementioned resistor mismatch codeword ratio, and outputs the resistor mismatch codeword M for compensating the resistor mismatch under the current input conditions. Figure 6 The resistance mismatch self-calibration value shown is Res Mismatch Self Calibration.

[0105] The residual mismatch codeword N and the resistance mismatch codeword M of the target operational amplifier are added together to obtain the adjustment codeword corresponding to the voltage to be compensated. The modulator outputs the adjustment codeword to the decoder, which decodes it to obtain the state control quantity for the compensation circuit.

[0106] Furthermore, in the calibration method for the offset voltage of the operational amplifier circuit provided in this application embodiment, step S404: determining the input resistance of the calibration circuit based on the unit compensation current and the voltage to be compensated, specifically includes:

[0107] After controlling the variable current source to output a unit compensation current, scan and determine the control code of the resistor calibration circuit when the minimum compensation error is determined, and record it as the initialization code of the decoder.

[0108] The residual mismatch codeword and the initialization codeword are scaled proportionally by calculations of digital circuits to obtain the codeword ratio of the least significant bit of the modulator corresponding to the decoder.

[0109] The control word for the resistor calibration circuit by the decoder is the quotient of the trimming codeword divided by the codeword ratio.

[0110] In a specific implementation, the determination of the magnitude and direction of the unit compensation current is also part of the decoder initialization settings. Then, in step S403: determining the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit according to the magnitude of the voltage to be compensated, and determining the direction of the unit compensation current according to the polarity of the voltage to be compensated can also be performed by the decoder. Specifically, during the process of initializing the residual mismatch codeword N of the target operational amplifier, the direction of the unit compensation current can be determined by judging the magnitude relationship between VOUTP and VOUTN or the sign of the residual mismatch codeword N, thereby determining whether the trimming codeword Offsetp_Trim > Offsetn_Trim or Offsetp_Trim < Offsetn_Trim. Among them, Offsetp_Trim is the positive trimming codeword for the resistor calibration circuit, and Offsetn_Trim is the negative trimming codeword for the resistor calibration circuit. Taking Figure 1 the compensation circuit shown as an example, please refer to Figure 8 , then Offsetp_Trim is the trimming codeword for the switches K 11 ~K 1(X+1) , and Offsetn_Trim is the trimming codeword for the switches K 21 ~K 2(X+1) .

[0111] After determining the unit compensation current, the decoder initialization process also needs to determine the relationship formula for converting the trimming codeword based on the foregoing unit compensation current. The solution is to scan and determine the control word of the resistor calibration circuit corresponding to the minimum compensation error after the variable current source outputs the unit compensation current, denoted as the initialization codeword N' of the decoder. Taking Figure 1 the compensation circuit shown as an example, please refer to Figure 8 . After determining the direction of the unit compensation current, one of the current connection points can be fixed, and the compensation current connection position of the remaining end can be scanned to determine the control word N' when Offsetp_Trim and Offsetn_Trim correspond to the minimum compensation error.

[0112] The residual mismatch codeword N of the target operational amplifier obtained by the above modulator and the control codeword N' corresponding to the decoder initialization are scaled proportionally through the calculation of the digital circuit, and finally, the codeword ratio corresponding to the 1-bit least significant bit (1bit LSB) of the unit bit of the modulator to the decoder can be obtained, so as to perform real-time difference calculation and self-calibration after the amplification circuit to be compensated enters the normal working mode.

[0113] In the above embodiment two, in order to further improve the compensation effect, given the known range of adjustment codeword difference, the connection position of the compensation circuit is determined based on the actual parameters in the application scenario: input common-mode voltage, input common-mode range, output common-mode voltage, output common-mode range, and resistance ratio. The basic principle is that the adjustment codeword corresponding to the compensation circuit connection position that minimizes the mismatch of the compensation current is the best result under test conditions such as high and low temperature and high and low voltage.

[0114] The foregoing detailed various embodiments of the method for calibrating the offset voltage of an operational amplifier circuit. Based on this, this application also discloses a calibration apparatus, system, and computer-readable storage medium for the offset voltage of an operational amplifier circuit corresponding to the above method.

[0115] Example 4

[0116] Figure 9 This is a schematic diagram of a calibration device for the offset voltage of an operational amplifier circuit provided in an embodiment of this application.

[0117] like Figure 9 As shown, the operational amplifier circuit offset voltage calibration device provided in this application embodiment includes:

[0118] Acquisition unit 901 is used to acquire the actual offset voltage of the amplifier circuit to be compensated;

[0119] The first calculation unit 902 is used to determine the voltage to be compensated based on the difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated.

[0120] The second calculation unit 903 is used to determine the magnitude of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit according to the magnitude of the voltage to be compensated, and to determine the direction of the unit compensation current according to the polarity of the voltage to be compensated.

[0121] The third calculation unit 904 is used to determine the connection resistance of the resistance calibration circuit of the compensation circuit based on the unit compensation current and the voltage to be compensated.

[0122] Control unit 905 is used to adjust the circuit state of the compensation circuit according to the unit compensation current and the connected resistance;

[0123] The first terminal of the resistor calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, the second terminal of the resistor calibration circuit is connected to the negative output terminal of the target amplifier, and the current calibration circuit is used to provide a unit compensation current to the resistor calibration circuit.

[0124] Furthermore, the calibration device for the offset voltage of the operational amplifier circuit provided in this application embodiment may further include:

[0125] The determination unit is used to determine the operational amplifier with the smallest offset voltage after compensation by connecting the compensation circuit under a preset test environment, based on the actual parameters of each operational amplifier in the amplifier circuit to be compensated.

[0126] Since the embodiments of the apparatus and the embodiments of the method correspond to each other, please refer to the description of the embodiments of the method for the embodiments of the apparatus, which will not be repeated here.

[0127] Example 5

[0128] Figure 10 This is a schematic diagram of a calibration system for the offset voltage of an operational amplifier circuit provided in an embodiment of this application.

[0129] like Figure 10 As shown, the operational amplifier circuit offset voltage calibration system provided in this application embodiment includes a compensation circuit 1001, a measurement circuit 1002, and a controller 1003;

[0130] The compensation circuit 1001 includes a current calibration circuit and a resistance calibration circuit. The first end of the resistance calibration circuit is connected to the positive input terminal of the target amplifier in the amplifier circuit to be compensated, and the second end of the resistance calibration circuit is connected to the negative output terminal of the target amplifier. The current calibration circuit is used to provide a unit compensation current to the resistance calibration circuit.

[0131] The measurement circuit 1002 is used to obtain the circuit parameters of the amplifier circuit to be compensated;

[0132] The controller 1003 is connected to the measurement circuit 1002 and the compensation circuit 1001 respectively, and is used to perform the steps of the calibration method for the offset voltage of the operational amplifier circuit as provided in any of the above embodiments.

[0133] Since the embodiments of the system part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the system part, and they will not be repeated here.

[0134] Example 6

[0135] Figure 11 This is a schematic diagram of a calibration device for the offset voltage of an operational amplifier circuit, provided in an embodiment of this application.

[0136] like Figure 11 As shown, the calibration device for the offset voltage of the operational amplifier circuit provided in this application embodiment includes:

[0137] The memory 1110 is used to store instructions, the instructions including the steps of the operational amplifier circuit offset voltage calibration method described in any of the above embodiments;

[0138] Processor 1120 is used to execute the instructions.

[0139] The processor 1120 may include one or more processing cores, such as a 3-core processor or an 8-core processor. The processor 1120 may be implemented using at least one hardware form selected from Digital Signal Processing (DSP), Field-Programmable Gate Array (FPGA), and Programmable Logic Array (PLA). The processor 1120 may also include a main processor and a coprocessor. The main processor, also known as a Central Processing Unit (CPU), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 1120 may integrate a Graphics Processing Unit (GPU), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 1120 may also include an Artificial Intelligence (AI) processor, which handles computational operations related to machine learning.

[0140] The memory 1110 may include one or more computer-readable storage media, which may be non-transitory. The memory 1110 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 1110 is used to store at least the following computer program 1111, wherein, after being loaded and executed by the processor 1120, the computer program 1111 is able to implement the relevant steps in the operational amplifier circuit offset voltage calibration method disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 1110 may also include an operating system 1112 and data 1113, etc., and the storage method may be temporary storage or permanent storage. The operating system 1112 may be Windows. The data 1113 may include, but is not limited to, the data involved in the above methods.

[0141] In some embodiments, the calibration device for operational amplifier circuit offset voltage may further include a display screen 1130, a power supply 1140, a communication interface 1150, an input / output interface 1160, a sensor 1170, and a communication bus 1180.

[0142] Those skilled in the art will understand that Figure 11The structure shown does not constitute a limitation on the calibration device for the offset voltage of the operational amplifier circuit and may include more or fewer components than shown.

[0143] The operational amplifier circuit offset voltage calibration device provided in this application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the operational amplifier circuit offset voltage calibration method as described above, with the same effect.

[0144] Example 7

[0145] It should be noted that the embodiments of the devices, systems, and equipment described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, or indirect coupling or communication connection between devices or modules, and may be electrical, mechanical, or other forms. Modules described as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0146] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.

[0147] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and executes all or part of the steps of the methods described in the various embodiments of this application.

[0148] Therefore, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements steps such as a calibration method for the offset voltage of an operational amplifier circuit.

[0149] The computer-readable storage medium may include various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0150] The computer program contained in the computer-readable storage medium provided in this embodiment can implement the steps of the operational amplifier circuit offset voltage calibration method as described above when executed by a processor, with the same effect.

[0151] The foregoing provides a detailed description of a method, apparatus, system, and computer-readable storage medium for calibrating the offset voltage of an operational amplifier circuit. The various embodiments are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The apparatus, system, device, and computer-readable storage medium disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0152] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method of calibrating an offset voltage of an operational amplifier circuit, characterized by, The method comprises: acquiring an actual offset voltage of an amplifier circuit to be compensated; determining a to-be-compensated voltage according to a difference between the actual offset voltage and an allowable offset voltage of the amplifier circuit to be compensated; determining a size of a unit compensation current of a variable current source in a current calibration circuit of a compensation circuit according to a size of the to-be-compensated voltage, and determining a direction of the unit compensation current according to a polarity of the to-be-compensated voltage; determining an access resistance of a resistance calibration circuit of the compensation circuit according to the unit compensation current and the to-be-compensated voltage; adjusting a circuit state of the compensation circuit according to the unit compensation current and the access resistance; wherein a first end of the resistance calibration circuit is connected to a positive input end of a target amplifier in the amplifier circuit to be compensated, a second end of the resistance calibration circuit is connected to a negative output end of the target amplifier, and the current calibration circuit is configured to provide the unit compensation current to the resistance calibration circuit; the resistance calibration circuit specifically comprises X compensation resistors with the same resistance value, X+1 first switches and X+1 second switches; and the current calibration circuit specifically comprises a first variable current source and a second variable current source; wherein each of the compensation resistors is connected in series between the first end of the resistance calibration circuit and the second end of the resistance calibration circuit, a first end of each of the first switches is connected to a first end of the first variable current source, a second end of each of the first switches is connected to a connection point between the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and each of the compensation resistors, a first end of each of the second switches is connected to a first end of the second variable current source, and a second end of each of the second switches is connected to a connection point between the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and each of the compensation resistors; wherein X is a positive integer.

2. The calibration method of claim 1, wherein, The to-be-compensated voltage is determined according to a difference between the actual offset voltage and the allowable offset voltage of the amplifier circuit to be compensated, specifically comprising: equalizing a voltage at a positive input end of a target operational amplifier in the amplifier circuit to be compensated, a voltage at a negative input end of the target operational amplifier, a common-mode input voltage of the target operational amplifier and a common-mode output voltage of the target operational amplifier, connecting a positive output end of the target operational amplifier and a negative output end of the target operational amplifier to input ends of a modulator respectively, and recording a difference between an output code word of the modulator and a center code word of the modulator as a residual mismatch code word of the target operational amplifier at this time. The voltage of the positive input terminal of the target operational amplifier, the voltage of the negative input terminal of the target operational amplifier, and the common-mode input voltage of the target operational amplifier are equal, and the positive output terminal of the target operational amplifier and the negative output terminal of the target operational amplifier are connected to the input terminals of a modulator, respectively; the common-mode input voltage of the target operational amplifier is equal to the lower limit of the common-mode input voltage range, and the difference between the output code word of the modulator and the center code word at this time is recorded as the lower limit of the output variable; the common-mode input voltage of the target operational amplifier is equal to the upper limit of the common-mode input voltage range, and the difference between the output code word of the modulator and the center code word at this time is recorded as the upper limit of the output variable; the difference between the upper limit of the common-mode input voltage range and the lower limit of the common-mode input voltage range is obtained as a first difference value, and the difference between the upper limit of the output variable and the lower limit of the output variable is obtained as a second difference value, and the ratio of the second difference value to the first difference value is recorded as the resistance mismatch code word ratio of the to-be-compensated amplification circuit; The resistance mismatch code word of the to-be-compensated amplification circuit is calculated according to the resistance mismatch code word ratio, the actual common-mode input voltage of the target operational amplifier, and the actual common-mode output voltage of the target operational amplifier; The residual mismatch code word and the resistance mismatch code word are superimposed to obtain a tuning code word corresponding to the to-be-compensated voltage; The center code word is the output code word of the modulator when the offset voltage is zero.

3. The method of calibration of claim 2, wherein, The access resistance of the resistance calibration circuit of the compensation circuit is determined according to the unit compensation current and the to-be-compensated voltage, specifically including: After the variable current source outputs the unit compensation current, the control code word of the resistance calibration circuit corresponding to the minimum compensation error is scanned and determined, and is recorded as the initialization code word of the decoder; The residual mismatch code word and the initialization code word are scaled by the calculation of the digital circuit to obtain the code word ratio corresponding to the unit bit least significant bit of the modulator. The quotient of the tuning code word divided by the code word ratio is the control code word of the decoder to the resistance calibration circuit.

4. The method of calibration of claim 1, wherein, The size of the unit compensation current of the variable current source in the current calibration circuit of the compensation circuit is determined according to the size of the to-be-compensated voltage, specifically including: Under the premise of meeting the size of the to-be-compensated voltage, the smallest unit compensation current that the variable current source can provide is selected.

5. The method of calibration of claim 1, wherein, The direction of the unit compensation current is determined according to the polarity of the to-be-compensated voltage, specifically including: The direction of the unit compensation current is determined according to the size relationship between the voltage of the positive output terminal of the target operational amplifier in the to-be-compensated amplification circuit and the voltage of the negative output terminal of the target operational amplifier.

6. The method of calibration of claim 1, wherein, Further comprising: According to the actual parameters of each operational amplifier in the to-be-compensated amplification circuit, the operational amplifier with the minimum offset voltage after compensation under the preset test environment is determined as the target operational amplifier.

7. An apparatus for calibrating the offset voltage of an operational amplifier circuit, characterized by Including: An acquisition unit is configured to acquire an actual offset voltage of a to-be-compensated amplification circuit; a first calculation unit configured to determine a to-be-compensated voltage according to a difference between the actual offset voltage and an allowable offset voltage of the to-be-compensated amplification circuit; a second calculation unit configured to determine a size of a unit compensation current of a variable current source in a current calibration circuit of the compensation circuit according to a size of the to-be-compensated voltage, and determine a direction of the unit compensation current according to a polarity of the to-be-compensated voltage; a third calculation unit configured to determine an access resistance of a resistance calibration circuit of the compensation circuit according to the unit compensation current and the to-be-compensated voltage; a control unit configured to adjust a circuit state of the compensation circuit according to the unit compensation current and the access resistance; wherein a first end of the resistance calibration circuit is connected to a positive input end of a target amplifier in the to-be-compensated amplification circuit, a second end of the resistance calibration circuit is connected to a negative output end of the target amplifier, and the current calibration circuit is configured to provide the unit compensation current to the resistance calibration circuit; the resistance calibration circuit specifically includes X compensation resistors with the same resistance value, X+1 first switches and X+1 second switches; and the current calibration circuit specifically includes a first variable current source and a second variable current source. wherein each of the compensation resistors is connected in series between the first end of the resistance calibration circuit and the second end of the resistance calibration circuit, a first end of each of the first switches is connected to a first end of the first variable current source, a second end of each of the first switches is connected to a connection point between the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and each of the compensation resistors, a first end of each of the second switches is connected to a first end of the second variable current source, and a second end of each of the second switches is connected to a connection point between the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and each of the compensation resistors. wherein X is a positive integer.

8. A system for calibrating the offset voltage of an operational amplifier circuit, characterized by The compensation circuit, the measurement circuit and the controller are included. The compensation circuit includes a current calibration circuit and a resistance calibration circuit; a first end of the resistance calibration circuit is connected to a positive input end of a target amplifier in the to-be-compensated amplification circuit, a second end of the resistance calibration circuit is connected to a negative output end of the target amplifier, and the current calibration circuit is configured to provide a unit compensation current to the resistance calibration circuit. The measurement circuit is configured to acquire a circuit parameter of the to-be-compensated amplification circuit. The controller is connected to the measurement circuit and the compensation circuit respectively, and is configured to perform the steps of the method for calibrating an offset voltage of an operational amplification circuit according to any one of claims 1 to 6. the resistance calibration circuit specifically includes X compensation resistors with the same resistance value, X+1 first switches and X+1 second switches; and the current calibration circuit specifically includes a first variable current source and a second variable current source. The first end of each of the first switches is connected to the first end of the first variable current source, the second end of each of the first switches is connected to the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and the connection point between each of the compensation resistors, the first end of each of the second switches is connected to the first end of the second variable current source, and the second end of each of the second switches is connected to the first end of the resistance calibration circuit, the second end of the resistance calibration circuit and the connection point between each of the compensation resistors. X is a positive integer.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by a processor to implement the steps of the method for calibrating the offset voltage of the operational amplifier circuit according to any one of claims 1 to 6.

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