Calibration method and calibration device

Abstract

A calibration method and calibration apparatus are disclosed, wherein the method is applicable to an operational amplifier. The operational amplifier has a first input stage, a second input stage, a first output stage, and a second output stage, the first input stage being coupled to the second output stage, and the second input stage being coupled to the first output stage. The calibration method includes: turning off the second input stage; measuring a first offset voltage of the first input stage when the second input stage is off and the first and second output stages are connected in series in a first manner; connecting the first and second output stages in series in a second manner different from the first manner; and measuring a second offset voltage of the first input stage when the second input stage is off and the first and second output stages are connected in series in the second manner.

Description

Technical Field

[0001] This invention relates to a calibration method and a calibration apparatus, and more particularly to a calibration method and a calibration apparatus for measuring the offset voltage of an operational amplifier. Background Technology

[0002] In operational amplifiers employing Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), ideally, when the gate voltages of the input transistor pairs are equal, the drain currents of the input transistor pairs are equal and stable. However, due to process variations in MOSFETs, operational amplifiers often possess a slight offset voltage. Furthermore, given the very high gain of operational amplifiers, even a small offset voltage, amplified by the amplifier's gain, can significantly impact the output. Therefore, it is necessary to measure the offset voltage of operational amplifiers to suppress it. Summary of the Invention

[0003] This invention presents a calibration method for operational amplifiers to accurately measure their offset voltage, enabling users to finely adjust the offset voltage for specific operational amplifier applications. Furthermore, the calibration method proposed in this invention can also separately determine the individual offset voltages of the input and output stages.

[0004] In view of this, the present invention proposes a calibration method applicable to an operational amplifier, wherein the operational amplifier has a first input stage, a second input stage, a first output stage, and a second output stage, the first input stage being coupled to the second output stage, and the second input stage being coupled to the first output stage. The calibration method includes: turning off the second input stage; when the second input stage is off and the first and second output stages are connected in series in a first manner, measuring a first offset voltage of the first input stage, wherein the first offset voltage is the sum of the offset voltage of the first input stage, a first equivalent value, and a second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage relative to the first input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage relative to the first input stage; connecting the first and second output stages in series in a second manner, wherein the first and second manners are different; when the second input stage is off and the first and second output stages are connected in series in the second manner, measuring the first offset voltage of the first input stage... A second offset voltage of the input stage; turning off the first input stage; when the first input stage is turned off and the first output stage and the second output stage are connected in series in the first manner, measuring a third offset voltage of the second input stage, wherein the third offset voltage is the sum of the offset voltage of the second input stage, the first equivalent value, and the second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage to the second input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage to the second input stage; connecting the first output stage and the second output stage in series in the second manner; and when the first input stage is turned off and the first output stage and the second output stage are connected in series in the second manner, measuring a fourth offset voltage of the second input stage.

[0005] According to an embodiment of the present invention, the first output stage includes a first sub-output stage and a second sub-output stage, and the second output stage includes a third sub-output stage and a fourth sub-output stage. When the first output stage and the second output stage are connected in series in the first manner, the first sub-output stage and the third sub-output stage are connected in series with each other, and the second sub-output stage and the fourth sub-output stage are connected in series with each other. When the first output stage and the second output stage are connected in series in the second manner, the first sub-output stage and the fourth sub-output stage are connected in series with each other, and the second sub-output stage and the third sub-output stage are connected in series with each other.

[0006] According to an embodiment of the present invention, the calibration method further includes: calculating a voltage calibration value of the operational amplifier based on the first offset voltage, the second offset voltage, the third offset voltage, and the fourth offset voltage.

[0007] According to one embodiment of the present invention, the second offset voltage is the offset voltage of the first input stage minus the first equivalent value plus the second equivalent value. The calibration method further includes: performing mathematical operations on the first offset voltage and the second offset voltage to obtain a first value, wherein the first value is the sum of the offset voltage of the first input stage and the second equivalent value.

[0008] According to an embodiment of the present invention, the fourth offset voltage is the offset voltage of the second input stage plus the first equivalent value minus the second equivalent value, wherein the calibration method further includes: performing mathematical operations on the third offset voltage and the fourth offset voltage to obtain a second value, wherein the second value is the sum of the offset voltage of the second input stage and the first equivalent value; and calculating the voltage calibration value of the operational amplifier based on the first value and the second value, wherein the voltage calibration value is the sum of the first value and the second value.

[0009] The present invention further proposes a calibration apparatus for performing a calibration method to calibrate an operational amplifier, wherein the operational amplifier has a first input stage, a second input stage, a first output stage, and a second output stage, the first input stage being coupled to the second output stage, and the second input stage being coupled to the first output stage, wherein the calibration method includes: turning off the second input stage; when the second input stage is turned off and the first output stage and the second output stage are connected in series in a first manner, measuring a first offset voltage of the first input stage, wherein the first offset voltage is the sum of the offset voltage of the first input stage, a first equivalent value, and a second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage relative to the first input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage relative to the first input stage; connecting the first output stage and the second output stage in series in a second manner, wherein the first and second equivalent values ​​are connected in series in a second manner. The second method described above is different; when the second input stage is off and the first output stage and the second output stage are connected in series in the second method, a second offset voltage of the first input stage is measured; the first input stage is off; when the first input stage is off and the first output stage and the second output stage are connected in series in the first method, a third offset voltage of the second input stage is measured, wherein the third offset voltage is the sum of the offset voltage of the second input stage, the first equivalent value, and the second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage relative to the second input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage relative to the second input stage; the first output stage and the second output stage are connected in series in the second method; and when the first input stage is off and the first output stage and the second output stage are connected in series in the second method, a fourth offset voltage of the second input stage is measured.

[0010] According to an embodiment of the present invention, the first output stage includes a first sub-output stage and a second sub-output stage, and the second output stage includes a third sub-output stage and a fourth sub-output stage. When the first output stage and the second output stage are connected in series in the first manner, the first sub-output stage and the third sub-output stage are connected in series with each other, and the second sub-output stage and the fourth sub-output stage are connected in series with each other. When the first output stage and the second output stage are connected in series in the second manner, the first sub-output stage and the fourth sub-output stage are connected in series with each other, and the second sub-output stage and the third sub-output stage are connected in series with each other.

[0011] According to an embodiment of the present invention, the calibration method further includes: calculating a voltage calibration value of the operational amplifier based on the first offset voltage, the second offset voltage, the third offset voltage, and the fourth offset voltage.

[0012] According to an embodiment of the present invention, the second offset voltage is the offset voltage of the first input stage minus the first equivalent value plus the second equivalent value, wherein the calibration method further includes: performing mathematical operations on the first offset voltage and the second offset voltage to obtain a first value, wherein the first value is the sum of the offset voltage of the first input stage and the second equivalent value.

[0013] According to an embodiment of the present invention, the fourth offset voltage is the offset voltage of the second input stage plus the first equivalent value minus the second equivalent value, wherein the calibration method further includes: performing mathematical operations on the third offset voltage and the fourth offset voltage to obtain a second value, wherein the second value is the sum of the offset voltage of the second input stage and the first equivalent value; and calculating the voltage calibration value of the operational amplifier based on the first value and the second value, wherein the voltage calibration value is the sum of the first value and the second value.

[0014] This invention presents a calibration method for operational amplifiers to accurately measure their offset voltage, enabling users to finely adjust the offset voltage for specific operational amplifier applications. Furthermore, the calibration method proposed in this invention can also separately determine the individual offset voltages of the input and output stages. Attached Figure Description

[0015] Figure 1 A circuit diagram of an operational amplifier according to an embodiment of the present invention is shown;

[0016] Figure 2 A flowchart of a calibration method according to an embodiment of the present invention is shown;

[0017] Figure 3 A circuit diagram of an operational amplifier according to another embodiment of the present invention is shown; and

[0018] Figure 4 A block diagram of a calibration apparatus according to an embodiment of the present invention is shown.

[0019] Attached icon number

[0020] 100, 300: Operational amplifiers

[0021] 110: First Input Level

[0022] 120: Second Input Level

[0023] 130: First Output Stage

[0024] 131: First sub-output stage

[0025] 132: Second Sub-output Stage

[0026] 140: Second Output Stage

[0027] 141: Third Sub-Output Stage

[0028] 142: Fourth Sub-Level Output

[0029] MN1: First N-type transistor

[0030] MN2: Second type N transistor

[0031] MP1: First P-type transistor

[0032] MP2: Second P-type transistor

[0033] INN: Negative input terminal

[0034] INP: Positive Input Terminal

[0035] IC1: First Current Source

[0036] IC2: Second current source

[0037] IB1: First bias current

[0038] IB2: Second Current

[0039] VI1: First transverse pressure

[0040] VI2: Second transverse pressure

[0041] VDD: Supply voltage

[0042] VCM: Common-mode voltage

[0043] OUT: Output terminal

[0044] S201~S211: Procedure Flow Detailed Implementation

[0045] The following description is an embodiment of the present invention. Its purpose is to illustrate the general principles of the invention and should not be considered as a limitation thereof. The scope of the invention is defined by the claims.

[0046] It is understood that although terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms, and these terms are only used to distinguish different elements, components, regions, layers, and / or portions. Therefore, a first element, component, region, layer, and / or portion discussed below may be referred to as a second element, component, region, layer, and / or portion without departing from the teachings of some embodiments disclosed herein.

[0047] It is worth noting that the following disclosure provides multiple embodiments or examples for practicing different features of the invention. The specific examples and arrangements of elements described below are merely for briefly illustrating the spirit of the invention and are not intended to limit its scope. Furthermore, the same element symbols or words may be repeated in multiple examples in the following description. However, the purpose of repetition is only to provide a simplified and clear explanation and is not intended to limit the relationship between the various embodiments and / or configurations discussed below. Moreover, descriptions in the following description of a feature being connected to, coupled to, and / or formed on another feature may actually encompass multiple different embodiments, including direct contact between the features, or additional features formed between the features, such that the features are not in direct contact.

[0048] Figure 1 This is a circuit diagram showing an operational amplifier according to an embodiment of the present invention. Figure 1 As shown, operational amplifier 100 includes a first input stage 110, a second input stage 120, a first output stage 130, and a second output stage 140. According to one embodiment of the present invention, operational amplifier 100 is a folded operational amplifier. This invention is explained herein only using the folded operational amplifier as an example and is not intended to limit operational amplifiers to this. In other words, the calibration method proposed in this invention is applicable to various operational amplifiers.

[0049] like Figure 1 As shown, the first input stage 110 includes a first N-type transistor MN1 and a second N-type transistor MN2. The gate of the first N-type transistor MN1 is coupled to the negative input terminal INN of the operational amplifier 100, the source of the first N-type transistor MN1 is coupled to the first current source IC1, and the drain of the first N-type transistor MN1 is coupled to the second output stage 140.

[0050] The gate of the second N-type transistor MN2 is coupled to the positive input terminal INP of the operational amplifier, the source terminal of the second N-type transistor MN2 is coupled to the first current source IC1, and the drain terminal of the second N-type transistor MN2 is coupled to the second output stage 140. The first current source IC1 is used to generate a first bias current IB1 flowing from the source terminals of the first N-type transistor MN1 and the second N-type transistor MN2 to the ground terminal, and the first current source IC1 has a first cross voltage VI1 across its terminals.

[0051] like Figure 1 As shown, the second input stage 120 includes a first P-type transistor MP1 and a second P-type transistor MP2. The gate of the first P-type transistor MP1 is coupled to the negative input terminal INN of the operational amplifier 100, the source of the first P-type transistor MP1 is coupled to the second current source IC2, and the drain of the first P-type transistor MP1 is coupled to the first output stage 130.

[0052] The gate of the second P-type transistor MP2 is coupled to the positive input terminal INP of the operational amplifier, the source terminal of the second P-type transistor MP2 is coupled to the second current source IC2, and the drain terminal of the second P-type transistor MP2 is coupled to the first output stage 130. The second current source IC2 is used to generate a second bias current IB2 flowing from the supply voltage VDD to the source terminals of the first P-type transistor MP1 and the second P-type transistor MN2, and the second current source IC2 has a second cross voltage VI2 across its terminals.

[0053] like Figure 1 As shown, the first output stage 130 includes a first sub-output stage 131 and a second sub-output stage 132. The drain of the first P-type transistor MP1 is coupled to the first sub-output stage 131, and the drain of the second P-type transistor MP2 is coupled to the second sub-output stage 132.

[0054] The second output stage 140 includes a third sub-output stage 141 and a fourth sub-output stage 142. The drain of the first N-type transistor MN1 is coupled to the third sub-output stage 141, and the drain of the second N-type transistor MN2 is coupled to the fourth sub-output stage 142. Figure 1 As shown, the third sub-output stage 141 and the first sub-output stage 131 are connected in series between the supply voltage VDD and the ground terminal, and the fourth sub-output stage 142 and the second sub-output stage 132 are connected in series between the supply voltage VDD and the ground terminal, wherein the output terminal OUT of the operational amplifier 100 is located between the fourth sub-output stage 142 and the second sub-output stage 132.

[0055] To measure the offset voltage of operational amplifier 110, the second input stage 120 is first turned off, and the first offset voltage VOS1 of the first input stage 110 is measured. The first offset voltage VOS1 is the first input-to-pair offset voltage VOSIN of the first input stage 110, the first equivalent value VOSN of the offset voltage of the first output stage 130 relative to the first input stage 110, and the second equivalent value VOSP of the offset voltage of the second output stage 140 relative to the first input stage 110. The first offset voltage VOS1 is shown in Equation 1:

[0056] VOS1=VOSIN+VOSN+VOSP (Formula 1)

[0057] According to one embodiment of this disclosure, the second input stage 120 can be turned off by adjusting the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP. In other words, the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP is selected to be greater than the supply voltage VDD minus the threshold voltage VTH of the first P-type transistor MP1 or the second P-type transistor MP2 minus the second cross-voltage VI2 of the second current source IC2, so that the source-gate cross-voltage of the first P-type transistor MP1 and the second P-type transistor MP2 is less than the threshold voltage VTH and therefore not turned on. The common-mode voltage VCM is shown in Equation 2:

[0058] VCM≥VDD-VTH-VI2 (Formula 2)

[0059] According to another embodiment of the present invention, the second current source IC2 can be controlled by a switch to stop generating the second current IB2, thereby turning off the second input stage 120. When the second current source IC2 is not conducting, the second input stage 120 is open-circuited and does not operate.

[0060] Similarly, the first input stage 110 can be turned off, and the second offset voltage VOS2 of the second input stage 120 can be measured. The second offset voltage VOS2 is the second input-to-offset voltage VOSIP of the second input stage 120, the first equivalent value VOSN of the offset voltage of the first output stage 130 relative to the second input stage 120, and the second equivalent value VOSP of the offset voltage of the second output stage 140 relative to the second input stage 120. The second offset voltage VOS2 is shown in Equation 3:

[0061] VOS2=VOSIP+VOSN+VOSP (Formula 3)

[0062] According to one embodiment of this disclosure, the first input stage 110 can be turned off by adjusting the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP, wherein the common-mode voltage VCM is less than the threshold voltages of the first N-type transistor MN1 and the second N-type transistor MN2. According to another embodiment of the present invention, the first input stage 110 can be turned off by using a switch to control the first current source IC1 to stop generating the first current IB1. When the first current source IC1 is not conducting, the first input stage 110 is open-circuited and does not operate.

[0063] According to one embodiment of the present invention, the explanation is provided here with the example that the equivalent value of the offset voltage of the first output stage 130 at the first input stage 110 is equal to the equivalent value of the offset voltage of the first output stage 130 at the second input stage 120, and the equivalent value of the offset voltage of the second output stage 140 at the first input stage 110 is equal to the equivalent value of the offset voltage of the second output stage 140 at the second input stage 120, in order to simplify the present invention, but it is not limited thereto. When the offset voltages of the first output stage 130 and the second output stage 140 are different from the equivalent values ​​of the first input stage 110 and the second input stage 120, the first equivalent value VOSN and the second equivalent value VOSP must also be corrected accordingly.

[0064] According to an embodiment of the present invention, when the operational amplifier 100 uses both the first input stage 110 and the second input stage 120 as input stages, the voltage calibration value VOST applicable to the operational amplifier 100 is the sum of the first offset voltage VOS1 and the second offset voltage VOS2, wherein the voltage calibration value VOST is as shown in Formula 4:

[0065] VOST=VOSIN+VOSIP+2×(VOSN+VOSP) (Formula 4)

[0066] As shown in Equation 4, when operational amplifier 100 uses both the first input stage 110 and the second input stage 120 as input stages, the first equivalent value VOSN of the first output stage 130 and the second equivalent value VOSP of the second output stage 140 are calculated repeatedly. In other words, the calculation methods of Equations 1 and 2 are applicable when operational amplifier 100 uses only the first input stage 110 or the second input stage 120 as input stages. When operational amplifier 100 uses both the first input stage 110 and the second input stage 120 as input stages, other methods are needed to obtain a more accurate voltage calibration value VOST.

[0067] Figure 2 A flowchart of a calibration method according to an embodiment of the present invention is shown. The following description of calibration method 200 will be based on… Figure 1 The operational amplifier 100 is described in more detail.

[0068] like Figure 2 First, the second input stage 120 of operational amplifier 100 is turned off (step S201). Then, the first offset voltage VOS1 of the first input stage 110 is measured (step S202), where the first offset voltage VOS1 is as shown in Formula 5:

[0069] VOS1=VOSIN+VOSN+VOSP (Formula 5)

[0070] According to one embodiment of the present invention, the second input stage 120 can be turned off by adjusting the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP. That is, the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP is selected to be greater than the supply voltage VDD minus the threshold voltage of the first P-type transistor MP1 and the second P-type transistor MP2 minus the second cross-voltage VI2 of the second current source IC2, so that the source-gate cross-voltage of the first P-type transistor MP1 and the second P-type transistor MP2 is less than the threshold voltage and therefore not turned on.

[0071] According to another embodiment of the present invention, the second current source IC2 can be controlled by a switch to stop generating the second current IB2, thereby turning off the second input stage 120. When the second current source IC2 is not conducting, the second input stage 120 is open-circuited and does not operate.

[0072] Next, the series connection of the first output stage 130 and the second output stage 140 is changed (step S203). After changing the series connection of the first output stage 130 and the second output stage 140, the second offset voltage VOS2 of the first input stage 110 is measured.

[0073] Figure 3 A circuit diagram of an operational amplifier according to another embodiment of the present invention is shown. Figure 3 operational amplifier 300 and Figure 1 Compared to operational amplifier 100, operational amplifier 300 has its third sub-output stage 141 and second sub-output stage 133 connected in series between the supply voltage VDD and ground, and its fourth sub-output stage 142 and first sub-output stage 131 connected in series between the supply voltage VDD and ground. Furthermore, the output terminal OUT is located between the fourth sub-output stage 142 and the first sub-output stage 131. In other words, the series connection method of the first output stage 130 and the second output stage 140 of operational amplifier 300 differs from that of operational amplifier 100.

[0074] When step S203 is executed, the series connection of the first output stage 130 and the second output stage 140 of operational amplifier 100 is changed to the series connection of the first output stage 130 and the second output stage 140 of operational amplifier 300. Furthermore, measurements are taken. Figure 3The second offset voltage VOS2 of the first input stage 110 of the operational amplifier 300 (step S204), wherein the second offset voltage VOS2 is as shown in Formula 6:

[0075] VOS2=VOSIN-VOSN+VOSP (Formula 6)

[0076] Next, the first offset voltage VOS1 (Formula 5) and the second offset voltage VOS2 (Formula 6) are added together and divided by 2 to obtain the first value V1 (step S205). The first value V1 is equal to the sum of the first input pair offset voltage VOSIN of the first input stage 110 and the second equivalent value VOSP of the offset voltage of the second output stage 140 relative to the first input stage 110, as shown in Formula 7:

[0077] V1=VOSIN+VOSP (Formula 7)

[0078] Back Figure 2 After step S205, the first input stage 110 of operational amplifier 100 is turned off (step S206). Next, the third offset voltage VOS3 of the second input stage 120 is measured (step S207), where the third offset voltage VOS3 is as shown in Formula 8:

[0079] VOS3=VOSIP+VOSN+VOSP (Formula 8)

[0080] According to one embodiment of this disclosure, the first input stage 110 can be turned off by adjusting the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP, wherein the common-mode voltage VCM is less than the threshold voltages of the first N-type transistor MN1 and the second N-type transistor MN2. According to another embodiment of the present invention, the first input stage 110 can be turned off by using a switch to control the first current source IC1 to stop generating the first current IB1. When the first current source IC1 is not conducting, the first input stage 110 is open-circuited and does not operate.

[0081] Next, the connection method of the first output stage 130 and the second output stage 140 is changed (step S208). After changing the series connection method of the first output stage 130 and the second output stage 140, the fourth offset voltage VOS4 of the second input stage 120 is measured (step S209).

[0082] In other words, during step S208, the series connection of the first output stage 130 and the second output stage 140 of operational amplifier 100 is changed to the series connection of the first output stage 130 and the second output stage 140 of operational amplifier 300. Next, in step S209, measurement... Figure 3The fourth offset voltage VOS4 of the second input stage 120 of the operational amplifier 300 is as shown in Equation 9:

[0083] VOS4=VOSIP+VOSN-VOSP (Formula 9)

[0084] Subsequently, the third offset voltage VOS3 (Formula 8) and the fourth offset voltage VOS4 (Formula 9) are added together and divided by 2 to obtain the second value V2 (step S210). The second value V2 is equal to the sum of the second input pair offset voltage VOSIP of the second input stage 110 and the offset voltage of the first output stage 130 relative to the first equivalent value VOSN of the second input stage 120, as shown in Formula 10:

[0085] V2=VOSIP+VOSN (Formula 10)

[0086] Based on the first value V1 and the second value V2, the voltage calibration value VOST applicable to the operational amplifier 100 is calculated (step S211), where the voltage calibration value VOST is equal to the sum of the first value V1 and the second value V2, as shown in Formula 11:

[0087] VOST=VOSIN+VOSIP+VOSN+VOSP (Formula 11)

[0088] Comparing Formula 10 with Formula 4, using Figure 2 The calibration method 200 can obtain not only the offset voltage of operational amplifier 100 using only the first input stage 110 or the second input stage 120, but also the accurate voltage calibration value VOST of operational amplifier 100 using both the first input stage 110 and the second input stage 120 simultaneously. Therefore, users can calibrate operational amplifier 100 based on the common-mode voltage VCM of the negative input terminal INN and the positive input terminal INP of operational amplifier 100, thereby improving the performance of operational amplifier 100.

[0089] According to one embodiment of the present invention, when the voltage calibration value VOST is negative, the width of the second N-type transistor MN2 and / or the second P-type transistor MP2 can be increased to increase the transconductance of the positive input terminal INP. According to another embodiment of the present invention, when the voltage calibration value VOST is negative, a current can be added to ground at the drain terminal of the first N-type transistor MN1 to reduce the current flowing through the first N-type transistor MN1, thereby reducing the transconductance of the negative input terminal INN.

[0090] According to other embodiments of the present invention, when the voltage calibration value VOST is positive, the width of the first N-type transistor MN1 and / or the first P-type transistor MP1 can be increased to increase the transconductance of the negative input terminal INN. Similarly, a current can be added to ground at the drain terminal of the second N-type transistor MN2 to reduce the current flowing through the second N-type transistor MN2, thereby reducing the transconductance of the positive input terminal INP.

[0091] According to other embodiments of the present invention, the first input pair offset voltage VOSIN, the second input pair offset voltage VOSIP, the first equivalent value VOSN, and the second equivalent value VOSP can be obtained by adding and subtracting Equations 5 to 10. For example, the first equivalent value VOSN can be obtained by subtracting V1 (Equation 7) from VOS1 (Equation 5), and the second equivalent value VOSP can be obtained by subtracting V2 (Equation 10) from VOS3 (Equation 8). The difference between the second value V2 and the first equivalent value VOSN is the second input pair offset voltage VOSIP, and the difference between the first value V1 and the second equivalent value VOSP is the first input pair offset voltage VOSIN.

[0092] According to other embodiments of the present invention, the order of steps S201 to S205 and steps S206 to S210 of the calibration method 200 can be interchanged. In other words, the offset voltage of the second input stage 120 can be measured by first turning off the first input stage 110, and then the offset voltage of the first input stage 110 can be measured by turning off the second input stage 120.

[0093] Figure 4 A block diagram of a calibration apparatus according to an embodiment of the present invention is shown. Figure 4 As shown, the calibration device 400 includes a storage device 410 and a controller 420, wherein the storage device 410 stores machine-readable code. When the controller 420 accesses the code stored in the storage device 410, the controller 420 executes... Figure 2 The calibration method 200 is used to measure the offset voltage of the operational amplifier 100.

[0094] This invention presents a calibration method for operational amplifiers to accurately measure their offset voltage, enabling users to finely adjust the offset voltage for specific operational amplifier applications. Furthermore, the calibration method proposed in this invention can also separately determine the individual offset voltages of the input and output stages.

[0095] While the embodiments and advantages of this disclosure have been disclosed above, it should be understood that any person skilled in the art can make modifications, substitutions, and refinements without departing from the spirit and scope of this disclosure. Furthermore, the scope of protection of this disclosure is not limited to the processes, machines, manufacturing, material composition, apparatus, methods, and steps described in the specific embodiments of this specification. Any person skilled in the art can understand from the disclosure of some embodiments of this disclosure the current or future development of processes, machines, manufacturing, material composition, apparatus, methods, and steps, as long as they can perform substantially the same function or obtain substantially the same results in the embodiments described herein, and can be used according to some embodiments of this disclosure. Therefore, the scope of protection of this disclosure includes the aforementioned processes, machines, manufacturing, material composition, apparatus, methods, and steps. In addition, each claim constitutes an individual embodiment, and the scope of protection of this disclosure also includes combinations of various claim scopes and embodiments.

Claims

1. A calibration method, characterized in that, The calibration method is applicable to an operational amplifier having a first input stage, a second input stage, a first output stage, and a second output stage, wherein the first input stage is coupled to the second output stage, and the second input stage is coupled to the first output stage, wherein the calibration method includes: Close the second input level mentioned above; When the second input stage is off and the first output stage and the second output stage are connected in series in a first manner, a first offset voltage of the first input stage is measured, wherein the first offset voltage is the sum of the offset voltage of the first input stage, a first equivalent value and a second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage relative to the first input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage relative to the first input stage; The first output stage and the second output stage are connected in series in a second manner, wherein the first manner and the second manner are different; When the second input stage is turned off and the first output stage and the second output stage are connected in series in the second manner, a second offset voltage of the first input stage is measured. Close the first input level mentioned above; When the first input stage is off and the first output stage and the second output stage are connected in series in the first manner, a third offset voltage of the second input stage is measured, wherein the third offset voltage is the sum of the offset voltage of the second input stage, the first equivalent value, and the second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage to the second input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage to the second input stage; The first output stage and the second output stage are connected in series in the second manner described above; and When the first input stage is turned off and the first output stage and the second output stage are connected in series in the second manner, a fourth offset voltage of the second input stage is measured.

2. The calibration method as described in claim 1, characterized in that, The first output stage includes a first sub-output stage and a second sub-output stage, and the second output stage includes a third sub-output stage and a fourth sub-output stage. When the first output stage and the second output stage are connected in series in the first manner, the first sub-output stage and the third sub-output stage are connected in series with each other, and the second sub-output stage and the fourth sub-output stage are connected in series with each other. When the first output stage and the second output stage are connected in series in the second manner, the first sub-output stage and the fourth sub-output stage are connected in series with each other, and the second sub-output stage and the third sub-output stage are connected in series with each other.

3. The calibration method as described in claim 1, characterized in that, Including: A voltage calibration value for the operational amplifier is calculated based on the first offset voltage, the second offset voltage, the third offset voltage, and the fourth offset voltage.

4. The calibration method as described in claim 3, characterized in that, The aforementioned second offset voltage is the offset voltage of the aforementioned first input stage minus the aforementioned first equivalent value plus the aforementioned second equivalent value, wherein the aforementioned calibration method further includes: The first offset voltage and the second offset voltage are mathematically calculated to obtain a first value, wherein the first value is the sum of the offset voltage of the first input stage and the second equivalent value.

5. The calibration method as described in claim 4, characterized in that, The aforementioned fourth offset voltage is the offset voltage of the aforementioned second input stage plus the aforementioned first equivalent value minus the aforementioned second equivalent value, wherein the aforementioned calibration method further includes: Mathematical operations are performed on the aforementioned third offset voltage and fourth offset voltage to obtain a second value, wherein the second value is the sum of the offset voltage of the second input stage and the first equivalent value; and Based on the first value and the second value, the voltage calibration value of the operational amplifier is calculated, wherein the voltage calibration value is the sum of the first value and the second value.

6. A calibration device, characterized in that, A calibration method is performed to calibrate an operational amplifier, wherein the operational amplifier has a first input stage, a second input stage, a first output stage, and a second output stage, the first input stage being coupled to the second output stage, and the second input stage being coupled to the first output stage, wherein the calibration method includes: Close the second input level mentioned above; When the second input stage is off and the first output stage and the second output stage are connected in series in a first manner, a first offset voltage of the first input stage is measured, wherein the first offset voltage is the sum of the offset voltage of the first input stage, a first equivalent value and a second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage relative to the first input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage relative to the first input stage; The first output stage and the second output stage are connected in series in a second manner, wherein the first manner and the second manner are different; When the second input stage is turned off and the first output stage and the second output stage are connected in series in the second manner, a second offset voltage of the first input stage is measured. Close the first input level mentioned above; When the first input stage is off and the first output stage and the second output stage are connected in series in the first manner, a third offset voltage of the second input stage is measured, wherein the third offset voltage is the sum of the offset voltage of the second input stage, the first equivalent value, and the second equivalent value, wherein the first equivalent value is the equivalent value of the offset voltage of the first output stage to the second input stage, and the second equivalent value is the equivalent value of the offset voltage of the second output stage to the second input stage; The first output stage and the second output stage are connected in series in the second manner described above; and When the first input stage is turned off and the first output stage and the second output stage are connected in series in the second manner, a fourth offset voltage of the second input stage is measured.

7. The calibration apparatus of claim 6, wherein the first output stage includes a first sub-output stage and a second sub-output stage, the second output stage includes a third sub-output stage and a fourth sub-output stage, wherein when the first output stage and the second output stage are connected in series in the first manner, the first sub-output stage and the third sub-output stage are connected in series with each other, and the second sub-output stage and the fourth sub-output stage are connected in series with each other, wherein when the first output stage and the second output stage are connected in series in the second manner, the first sub-output stage and the fourth sub-output stage are connected in series with each other, and the second sub-output stage and the third sub-output stage are connected in series with each other.

8. The calibration apparatus of claim 6, wherein the calibration apparatus further comprises: A voltage calibration value for the operational amplifier is calculated based on the first offset voltage, the second offset voltage, the third offset voltage, and the fourth offset voltage.

9. The calibration apparatus of claim 8, wherein the second offset voltage is the offset voltage of the first input stage minus the first equivalent value plus the second equivalent value, wherein the calibration method further comprises: The first offset voltage and the second offset voltage are mathematically calculated to obtain a first value, wherein the first value is the sum of the offset voltage of the first input stage and the second equivalent value.

10. The calibration apparatus of claim 9, wherein the fourth offset voltage is the offset voltage of the second input stage plus the first equivalent value minus the second equivalent value, and wherein the calibration method further comprises: Mathematical operations are performed on the aforementioned third offset voltage and fourth offset voltage to obtain a second value, wherein the second value is the sum of the offset voltage of the second input stage and the first equivalent value; and Based on the first value and the second value, the voltage calibration value of the operational amplifier is calculated, wherein the voltage calibration value is the sum of the first value and the second value.

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