A high-precision integrated operational amplifier nonlinearity test system and test method

Abstract

The present invention discloses a high-precision integrated operational amplifier nonlinearity test system and test method, the system includes a high-precision signal voltage source, an auxiliary operational amplifier test device, a device to be tested, a signal acquisition and analysis system, a host computer and a plurality of switches. The method steps are as follows: 1) the input end of the auxiliary operational amplifier test device is sequentially connected to N input signals, and the output end sequentially outputs N output signals to the signal acquisition and analysis system; 2) the input end of the device to be tested is sequentially connected to N input signals, and the output end sequentially outputs N output signals to the signal acquisition and analysis system; 3) fitting an ideal input-output straight line; 4) the signal acquisition and analysis system determines the value of the ideal input-output straight line projected on the Y axis; 5) sequentially calculating the deviation between the output signal of the device to be tested and the ideal input-output straight line; 6) calculating the nonlinearity h. The present invention adopts the three steps of calibration-test-calculation, eliminates the errors of the auxiliary operational amplifier and the test system, and improves the test accuracy and stability.

Description

Technical Field

[0001] The invention relates to the field of integrated operational amplifier testing, in particular to a high-precision integrated operational amplifier nonlinearity testing system and testing method. Background Art

[0002] With the development of modern electronic information technology, the technology is becoming more and more advanced, and the nonlinearity accuracy of high-precision integrated operational amplifiers is getting higher and higher. The general test methods and instruments are increasingly exposing some defects and deficiencies. Therefore, higher requirements are put forward for the nonlinearity test system and test methods of high-precision operational amplifiers. In the traditional test method, it is necessary to add an offset adjustment potentiometer to adjust the initial offset voltage to zero, and a high-precision reference voltage source is required at both ends of the potentiometer to prevent output drift. The operation is cumbersome and there is a zero adjustment error during the zero adjustment process. It is not feasible for batch testing in actual production. In the test process, the maximum and minimum values ​​of the open-loop gain need to be calculated. Since the open-loop gain is large and the state is unstable, there is a certain error in the calculation of the open-loop gain. Summary of the invention

[0003] The purpose of the present invention is to provide a high-precision integrated operational amplifier nonlinearity test system, comprising a high-precision signal voltage source, an auxiliary operational amplifier test device, a device to be tested, a signal acquisition and analysis system, a host computer and a number of switches;

[0004] When the test system works in the calibration mode, the host computer controls the switch on and off so that the high-precision signal voltage source transmits the input signal to the auxiliary operational amplifier test device;

[0005] When the test system works in the test mode, the host computer controls the switch on and off, so that the high-precision signal voltage source transmits the input signal to the device under test;

[0006] The host computer transmits the input signal parameters to the signal acquisition and analysis system;

[0007] The signal acquisition and analysis system respectively acquires output signals of the auxiliary operational amplifier test device and the device under test;

[0008] The signal acquisition and analysis system fits an ideal input-output straight line according to the output signal of the auxiliary operational amplifier test device and the output signal of the device under test;

[0009] The signal acquisition and analysis system calculates the nonlinearity of the device under test according to the input signal parameters, the output signal of the device under test and the ideal input-output straight line.

[0010] Furthermore, the circuit topology of the high-precision integrated operational amplifier nonlinearity test system is as follows:

[0011] The output end of the high-precision signal voltage source is connected to the 3-point position of the switch K1; the 1-point position of the switch K1 is short-circuited with the 1-point position of the switch tube K2, and the 2-point position is short-circuited with the 2-point position of the switch tube K2;

[0012] The 1-point position of the switch tube K2 is connected to the positive input terminal of the device under test, and the 3-point position is connected in series with the resistor R2 and then connected to the positive input terminal of the auxiliary operational amplifier test device; the 3-point position of the switch tube K2 is short-circuited with the 2-point position of the switch K3;

[0013] The negative input terminal and output terminal of the device under test are short-circuited to form a unity gain buffer; the output terminal of the device under test is connected to the 1-point position of switch K3;

[0014] The 3-point position of switch K3 is connected in series with resistor R1 and then connected to the negative input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K3 is connected in series with resistor R1 and resistor Rf1 and then connected to the signal acquisition and analysis system;

[0015] The output end of the auxiliary operational amplifier test device is connected to the signal acquisition and analysis system.

[0016] Furthermore, the test system works in a dual power supply voltage mode; the 3-point position of the switch tube K2 is connected in series with resistors R2 and Rf2 and then grounded.

[0017] Furthermore, the test system works in a single power supply voltage mode; the 3-point series connection resistor R2 and resistor Rf2 of the switch tube K2 are connected to the reference voltage V REF =1 / 2*V S ; V S is the single supply voltage amplitude.

[0018] Furthermore, the closed-loop gain of the auxiliary operational amplifier test device is G=Rf2 / (Rf2+R2)*(1+Rf1 / R1).

[0019] Furthermore, the resistance Rf1 = Rf2, and the resistance R1 = R2.

[0020] Furthermore, when the test system works in the calibration mode, the 3 o'clock position and the 2 o'clock position of the switch K1 are short-circuited; the 3 o'clock position and the 2 o'clock position of the switch K2 are short-circuited; and the 3 o'clock position and the 2 o'clock position of the switch K3 are short-circuited.

[0021] Furthermore, when the test system works in the test mode, the 3 o'clock position and the 1 o'clock position of the switch K1 are short-circuited; the 3 o'clock position and the 1 o'clock position of the switch K2 are short-circuited; the 3 o'clock position and the 1 o'clock position of the switch K3 are short-circuited; the positive input terminal of the device under test and the positive input terminal of the auxiliary operational amplifier test device are short-circuited.

[0022] Furthermore, the high and low levels of the input signal are V INL 、V INH .

[0023] A testing method based on the high-precision integrated operational amplifier nonlinearity testing system comprises the following steps:

[0024] 1) Short-circuit the 3-point and 2-point positions of switch K1, short-circuit the 3-point and 2-point positions of switch K2, and short-circuit the 3-point and 2-point positions of switch K3, so that the test system works in calibration mode;

[0025] 2) The input end of the auxiliary operational amplifier test device is connected to N input signals in sequence, which are respectively denoted as V INL 、V INL +ΔV*1…………、V INL +ΔV*(N-2),V INH ; ΔV is the voltage increment;

[0026] 3) The output end of the auxiliary operational amplifier test device outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS11 、V OS12 ………、V OS1N ;

[0027] 4) Short-circuit the 3-point position and the 1-point position of switch K1, short-circuit the 3-point position and the 1-point position of switch K2, and short-circuit the 3-point position and the 1-point position of switch K3, so that the test system works in the test mode;

[0028] 5) The input terminal of the device under test is connected to N input signals in sequence, which are denoted as V INL 、V INL +ΔV*1…………、V INL +ΔV*(N-2),V INH ;

[0029] 6) The output end of the device under test outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS21 、V OS22 ………、V OS2N ;

[0030] 7) The signal acquisition and analysis system uses N input signals as the X-axis, subtracts the output signals of the two endpoints of the test mode and the calibration mode and connects them into a straight line as the ideal input-output straight line, and the slope of the straight line is α = ((V OS2N -V OS1N )-(V OS21 -V OS11 )) / (V INH -V INL );

[0031] 8) The signal acquisition and analysis system determines the value of the ideal input and output straight line projection on the Y axis, which are recorded as V OS31 =V INL *α、V OS32 =(VINL +ΔV*1)*α………、V OS3N =V INH *α;

[0032] 9) Calculate the deviation between the output signal of the device under test and the ideal input-output straight line, respectively, and record them as ΔE 1 =V OS21 -V OS11 -V OS31 , ΔE 2 =V OS22 -V OS12 -V OS32 , ………, ΔE N =V OS2N -V OS1N -V OS3N ;

[0033] 10) Calculate the nonlinearity h = (ΔE MAX -ΔE MIN ) / (2*G*(V INH -V INL ))*10 6 ; ΔE MAX , ΔE MIN are the maximum and minimum deviations, respectively.

[0034] It is worth noting that the present invention relates to a high-precision operational amplifier nonlinearity test system and test method for high-precision operational amplifier nonlinearity testing. The present invention comprises the following steps: 1) connecting the device under test into a buffer structure, and connecting the auxiliary operational amplifier into a double-end input subtractor structure. 2) switching the test system to a calibration mode, and inputting N sampling signals into the input end in sequence. 3) corresponding to the N input sampling signals, at the output end V OUT Save N output signals in sequence. 4) Switch the test system to the test mode and input N sampling signals in sequence at the input end (the test sampling signals are the same as the sampling signals during calibration). 5) Corresponding to the N input sampling signals, at the output end V OUT The N output signals are saved in sequence. 6) The difference is made according to the two measured values ​​and the nonlinearity is calculated. The present invention avoids the use of a zeroing potentiometer in a traditional structure by making a difference through the calibration and test comparison of the auxiliary operational amplifier, simplifies the test system structure and improves the test accuracy, and can be used for large-scale mass production testing.

[0035] The technical effect of the present invention is unquestionable. The present invention adds an auxiliary operational amplifier, uses software to automatically control the test system, adopts the three steps of calibration-test-calculation, eliminates the errors of the auxiliary operational amplifier and the test system, improves the test accuracy and stability, and can be used for batch testing and production. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is the main test system structure diagram of the present invention;

[0037] Figure 2 It is the structural diagram of the test system in the calibration mode;

[0038] Figure 3 It is the structural diagram of the test system in the test mode;

[0039] Figure 4 The ideal input and output curve and the actual sampling point distribution diagram. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0041] Embodiment 1:

[0042] See also Figures 1 to 4 , a high-precision integrated operational amplifier nonlinearity test system, including a high-precision signal voltage source, an auxiliary operational amplifier test device, a device to be tested, a signal acquisition and analysis system, a host computer and several switches;

[0043] When the test system works in the calibration mode, the host computer controls the switch on and off so that the high-precision signal voltage source transmits the input signal to the auxiliary operational amplifier test device;

[0044] When the test system works in the test mode, the host computer controls the switch on and off, so that the high-precision signal voltage source transmits the input signal to the device under test;

[0045] The host computer transmits the input signal parameters to the signal acquisition and analysis system;

[0046] The signal acquisition and analysis system respectively acquires output signals of the auxiliary operational amplifier test device and the device under test;

[0047] The signal acquisition and analysis system fits an ideal input-output straight line according to the output signal of the auxiliary operational amplifier test device and the output signal of the device under test;

[0048] The signal acquisition and analysis system calculates the nonlinearity of the device under test according to the input signal parameters, the output signal of the device under test and the ideal input-output straight line.

[0049] The circuit topology of the high-precision integrated operational amplifier nonlinearity test system is shown below:

[0050] The output end of the high-precision signal voltage source is connected to the 3-point position of the switch K1; the 1-point position of the switch K1 is short-circuited with the 1-point position of the switch tube K2, and the 2-point position is short-circuited with the 2-point position of the switch tube K2;

[0051] The 1-point position of the switch tube K2 is connected to the positive input terminal of the device under test, and the 3-point position is connected in series with the resistor R2 and then connected to the positive input terminal of the auxiliary operational amplifier test device; the 3-point position of the switch tube K2 is short-circuited with the 2-point position of the switch K3;

[0052] The negative input terminal and output terminal of the device under test are short-circuited to form a unity gain buffer; the output terminal of the device under test is connected to the 1-point position of switch K3;

[0053] The 3-point position of switch K3 is connected in series with resistor R1 and then connected to the negative input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K3 is connected in series with resistor R1 and resistor Rf1 and then connected to the signal acquisition and analysis system;

[0054] The output end of the auxiliary operational amplifier test device is connected to the signal acquisition and analysis system.

[0055] If the test system works in dual power supply voltage mode, the 3-point of the switch tube K2 is connected in series with the resistor R2 and the resistor Rf2 and then grounded.

[0056] If the test system works in single power supply voltage mode, the 3 points of switch tube K2 are connected in series with resistor R2 and resistor Rf2, followed by reference voltage V REF =1 / 2*V S ; V S is the single supply voltage amplitude.

[0057] The closed-loop gain G of the auxiliary operational amplifier test device = Rf2 / (Rf2+R2)*(1+Rf1 / R1).

[0058] Resistance Rf1=Rf2, resistance R1=R2.

[0059] When the test system works in the calibration mode, the 3 o'clock position and the 2 o'clock position of the switch K1 are short-circuited; the 3 o'clock position and the 2 o'clock position of the switch K2 are short-circuited; and the 3 o'clock position and the 2 o'clock position of the switch K3 are short-circuited.

[0060] When the test system works in the test mode, the 3-point position and the 1-point position of the switch K1 are short-circuited; the 3-point position and the 1-point position of the switch K2 are short-circuited; the 3-point position and the 1-point position of the switch K3 are short-circuited; the positive input terminal of the device under test and the positive input terminal of the auxiliary operational amplifier test device are short-circuited.

[0061] The input signal high and low levels are V INL 、V INH .

[0062] A testing method based on the high-precision integrated operational amplifier nonlinearity testing system comprises the following steps:

[0063] 1) Short-circuit the 3-point and 2-point positions of switch K1, short-circuit the 3-point and 2-point positions of switch K2, and short-circuit the 3-point and 2-point positions of switch K3, so that the test system works in calibration mode;

[0064] 2) The input end of the auxiliary operational amplifier test device is connected to N input signals in sequence, which are respectively denoted as V INL 、V INL +ΔV*1…………、V INL +ΔV*(N-2),V INH ; ΔV is the voltage increment;

[0065] 3) The output end of the auxiliary operational amplifier test device outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS11 、V OS12 ………、V OS1N ;

[0066] 4) Short-circuit the 3-point position and the 1-point position of switch K1, short-circuit the 3-point position and the 1-point position of switch K2, and short-circuit the 3-point position and the 1-point position of switch K3, so that the test system works in the test mode;

[0067] 5) The input terminal of the device under test is connected to N input signals in sequence, which are denoted as V INL 、V INL +ΔV*1…………、V INL +ΔV*(N-2),V INH ;

[0068] 6) The output end of the device under test outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS21 、V OS22 ………、V OS2N ;

[0069] 7) The signal acquisition and analysis system uses N input signals as the X-axis, subtracts the output signals of the two endpoints of the test mode and the calibration mode and connects them into a straight line as the ideal input-output straight line, that is, the first (V OS11 / V OS21 ) and the last one (V OS1N / V OS2N ) output signal and input signal (V INH / V INL ) to fit the ideal input-output straight line, the slope of the straight line α=((V OS2N -V OS1N )-(V OS21 -V OS11 )) / (V INH -V INL );

[0070] 8) The signal acquisition and analysis system determines the value of the ideal input and output straight line projection on the Y axis, which are recorded as V OS31 =V INL *α、V OS32 =(V INL +ΔV*1)*α………、V OS3N =V INH *α;

[0071] 9) Calculate the deviation between the output signal of the device under test and the ideal input-output straight line, respectively, and record them as ΔE 1 =V OS21 -V OS11 -V OS31 , ΔE 2 =V OS22 -V OS12 -V OS32 , ………, ΔE N =V OS2N -V OS1N -V OS3N ;

[0072] 10) Calculate the nonlinearity h = (ΔE MAX -ΔE MIN ) / (2*G*(V INH -V INL ))*10 6 ; ΔE MAX , ΔE MIN are the maximum and minimum deviations, respectively.

[0073] Embodiment 2:

[0074] See also Figures 1 to 3 A high-precision integrated operational amplifier nonlinearity test system comprises a high-precision signal voltage source, a device under test, an auxiliary operational amplifier test device, a signal acquisition and analysis system, and a switch control part.

[0075] The high-precision signal voltage source provides an arbitrary step sampling signal to the input terminal during the calibration stage and the test stage. The output terminal of the device under test and the inverting input terminal of the device under test are short-circuited to form a unit gain buffer structure. The positive input terminal of the device under test serves as the input terminal of the calibration signal and the test signal.

[0076] The auxiliary operational amplifier device and the four resistors Rf1 / Rf2 / R1 / R2 are connected to form a double-ended input subtractor structure, and the closed-loop gain of the auxiliary operational amplifier is determined by the four resistor values ​​G=Rf2 / (Rf2+R2)*(1+Rf1 / R1).

[0077] The four resistors Rf1=Rf2, R1=R2

[0078] The matching accuracy of the four resistors should satisfy ((Rf1 / R1)-(Rf2 / R2)) / (Rf2 / R2)<0.1%.

[0079] The signal acquisition and analysis system is connected to the output end of the auxiliary operational amplifier, extracts the output voltage value corresponding to different input sampling signal voltages in the calibration mode and the test mode, and calculates the output voltage value according to the set formula ΔE 1 =(V OS21 -V OS11 ) / G and nonlinearity = (ΔE MAX -ΔE MIN ) / (V INH -V INL )*10 6 Calculating Op Amp Nonlinearity

[0080] The switch control part mainly includes switches K1 / K2 / K3, wherein the 3-point position of switches K1 / K2 / K3 is a switchable position, and the 1-point position and the 2-point position are fixed positions. The calibration mode and the test mode are selected by switching the connection between the 3-point position of the switch and the 1-point position and the 2-point position.

[0081] The 1-point position of switch K1 is short-circuited with the 1-point position of switch K2, and the 2-point position of switch K1 is short-circuited with the 2-point position of switch K2.

[0082] Embodiment 3:

[0083] A high-precision integrated operational amplifier nonlinearity test system, the main structure of which is shown in Example 2, wherein the output end of the device under test is connected to the inverting input end of the device under test and the 1-point position of switch K3, the positive input end of the device under test is connected to the 1-point position of switch K1 / K2, and the 3-point position of switch K1 is used as a signal input end to connect to the output end of a high-precision signal voltage source. The 2-point position of switch K1 and the 2-point position of switch K2 are short-circuited, the 3-point position of switch K2 is connected to one end of resistor R2 and the 2-point position of switch K3, the other end of resistor R2 is connected to one end of Rf2 and the positive input end of the auxiliary operational amplifier, and the other end of resistor Rf2 is grounded or connected to a reference voltage V REF The 3-point position of the switch K3 is connected to one end of the resistor R1, the other end of the resistor R1 is connected to the negative input end of the auxiliary operational amplifier and one end of the resistor Rf1, and the other end of the resistor Rf1 is connected to the output end of the auxiliary operational amplifier and the input port of the computer.

[0084] Embodiment 4:

[0085] A high-precision integrated operational amplifier nonlinearity test system, the main structure of which is shown in Example 2, wherein the test system can work with dual power supply voltages, one end of the resistor Rf2 is grounded, and can also work with a single power supply voltage, one end of the resistor Rf2 is connected to a reference voltage V REF .

[0086] Embodiment 5:

[0087] A high-precision integrated operational amplifier nonlinearity test system, the main structure of which is shown in Example 2, wherein the 2-point and 3-point positions of switches K1 / K2 / K3 are short-circuited, and the test system is in a calibration mode; the 1-point and 3-point positions of switches K1 / K2 / K3 are short-circuited, and the test system is in a test mode.

[0088] Embodiment 6:

[0089] A high-precision integrated operational amplifier nonlinearity testing method comprises the following steps:

[0090] The test system operates on a dual power supply voltage, and one end of the resistor Rf1 is grounded.

[0091] Short-circuit the 3-point and 2-point positions of switch K1 / K2 / K3 to select the calibration mode.

[0092] The high-precision signal voltage source generates the first input sampling signal voltage of -12V, and records and saves the output voltage V at the output terminal VOUT of the test system. OS11 .

[0093] The high-precision signal voltage source generates a second input sampling signal. The second sampling signal value is 1V higher than the first sampling signal. OUT Record and save the output voltage V OS12 .

[0094] Repeat step 3) until the last input sampling signal voltage of 12V is generated, and the output terminal V OUT Record and save the output voltage V OS1N , N=25.

[0095] The 3-point position and 1-point position of switch K1 / K2 / K3 are short-circuited, and the test system switches from calibration mode to test mode.

[0096] In the test mode, the high-precision signal voltage source generates the first input sampling signal voltage of -12V, and the output terminal V OUT Record and save the output voltage V OS21 .

[0097] The high-precision signal voltage source generates a second input sampling signal. The second sampling signal value is 1V higher than the first sampling signal. OUT Record and save the output voltage V OS22 .

[0098] Repeat step 7) to generate the last input sampling signal voltage of 12V, at the output terminal V OUT Record and save the output voltage VOS2N , N=25.

[0099] 10) The output voltage (V OS21 -V OS11 )、(V OS2N -V OS1N ) as the two endpoints to draw a straight line, the slope of the line α=((V OS2N -V OS1N )-(V OS21 -V OS11 )) / 20, this straight line is used as the ideal input-output straight line, where the 21 input sampling signals -12V~12V are the X-axis.

[0100] 11) Corresponding to the 25 sampling signals at the input end, the values ​​of the N points corresponding to the Y axis of the ideal input-output straight line are V OS31 =V INL *α、V OS32 =(V INL +ΔV*1)*α………、V OS3N =V INH *α.

[0101] 12) Calculate the deviation between the actual output signal and the ideal input-output straight line, ΔE1 = V OS21 -V OS11 -V OS31 , ΔE 2 =V OS22 -V OS12 -V OS32 , ………, ΔE N =V OS2N -V OS1N -V OS3N , and find the maximum value ΔE MAX and ΔE MIN ,;

[0102] 13) According to the formula nonlinearity = (ΔE MAX -ΔE MIN ) / (2*G*(V INH -V INL ))*10 6 , G is the closed-loop gain of the op amp, and the output is displayed.

Claims

1. A high-precision integrated operational amplifier nonlinearity test system, characterized by: It includes high-precision signal voltage source, auxiliary operational amplifier test device, device under test, signal acquisition and analysis system, host computer and several switches; When the test system works in the calibration mode, the host computer controls the switch on and off so that the high-precision signal voltage source transmits the input signal to the auxiliary operational amplifier test device; When the test system works in the test mode, the host computer controls the switch on and off, so that the high-precision signal voltage source transmits the input signal to the device under test; The host computer transmits the input signal parameters to the signal acquisition and analysis system; The signal acquisition and analysis system respectively acquires output signals of the auxiliary operational amplifier test device and the device under test; The signal acquisition and analysis system fits an ideal input-output straight line according to the output signal of the auxiliary operational amplifier test device and the output signal of the device under test; The signal acquisition and analysis system calculates the nonlinearity of the device under test according to the input signal parameters, the output signal of the device under test and the ideal input-output straight line.

2. A high-precision integrated operational amplifier nonlinearity test system according to claim 1, characterized in that: The circuit topology of the high-precision integrated operational amplifier nonlinearity test system is shown below: The output end of the high-precision signal voltage source is connected to the 3-point position of switch K1; the 1-point position of switch K1 is short-circuited with the 1-point position of switch K2, and the 2-point position is short-circuited with the 2-point position of switch K2; The 1-point position of switch K2 is connected to the positive input terminal of the device under test, and the 3-point position is connected in series with resistor R2 and then connected to the positive input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K2 is short-circuited with the 2-point position of switch K3; The negative input terminal and output terminal of the device under test are short-circuited to form a unity gain buffer; the output terminal of the device under test is connected to the 1-point position of switch K3; The 3-point position of switch K3 is connected in series with resistor R1 and then connected to the negative input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K3 is connected in series with resistor R1 and resistor Rf1 and then connected to the signal acquisition and analysis system; The output end of the auxiliary operational amplifier test device is connected to the signal acquisition and analysis system.

3. A high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: The test system works in a dual power supply voltage mode; the 3-point position of the switch K2 is connected in series with the resistor R2 and the resistor Rf2 and then grounded.

4. A high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: The test system works in single power supply voltage mode; the 3-point switch K2 is connected in series with resistor R2 and resistor Rf2, and then connected to the reference voltage V REF =1 / 2*V S ; V S is the single supply voltage amplitude.

5. The high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: The closed-loop gain of the auxiliary op amp test device is G=Rf2 / (Rf2+R2)*(1+Rf1 / R1).

6. A high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: Resistance Rf1=Rf2, resistance R1=R2.

7. The high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: When the test system works in the calibration mode, the 3 o'clock position and the 2 o'clock position of the switch K1 are short-circuited; the 3 o'clock position and the 2 o'clock position of the switch K2 are short-circuited; and the 3 o'clock position and the 2 o'clock position of the switch K3 are short-circuited.

8. The high-precision integrated operational amplifier nonlinearity test system according to claim 2, characterized in that: When the test system works in the test mode, the 3-point position and the 1-point position of the switch K1 are short-circuited; the 3-point position and the 1-point position of the switch K2 are short-circuited; the 3-point position and the 1-point position of the switch K3 are short-circuited; the positive input terminal of the device under test and the positive input terminal of the auxiliary operational amplifier test device are short-circuited.

9. The high-precision integrated operational amplifier nonlinearity test system according to claim 1, characterized in that: The input signal high and low levels are V INL 、V INH .

10. A test method based on the high-precision integrated operational amplifier nonlinearity test system according to any one of claims 1 to 9, characterized in that: The following steps are involved: 1) Short-circuit the 3-point and 2-point positions of switch K1, short-circuit the 3-point and 2-point positions of switch K2, and short-circuit the 3-point and 2-point positions of switch K3, so that the test system works in calibration mode; The connection topology of switch K1, switch K2 and switch K3 is as follows: The output end of the high-precision signal voltage source is connected to the 3-point position of switch K1; the 1-point position of switch K1 is short-circuited with the 1-point position of switch K2, and the 2-point position is short-circuited with the 2-point position of switch K2; The 1-point position of switch K2 is connected to the positive input terminal of the device under test, and the 3-point position is connected in series with resistor R2 and then connected to the positive input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K2 is short-circuited with the 2-point position of switch K3; The negative input terminal and output terminal of the device under test are short-circuited to form a unity gain buffer; the output terminal of the device under test is connected to the 1-point position of switch K3; The 3-point position of switch K3 is connected in series with resistor R1 and then connected to the negative input terminal of the auxiliary operational amplifier test device; the 3-point position of switch K3 is connected in series with resistor R1 and resistor Rf1 and then connected to the signal acquisition and analysis system; The output end of the auxiliary operational amplifier test device is connected to the signal acquisition and analysis system; 2) The input end of the auxiliary operational amplifier test device is connected to N input signals in sequence, which are respectively denoted as V INL 、V INL +ΔV*1, ..., V INL +ΔV * (N-2), V INH ; ΔV is the voltage increment; the high and low levels of the input signal are V INL 、V INH ; 3) The output end of the auxiliary operational amplifier test device outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS11 、V OS12 ,……,V OS1N ; 4) Short-circuit the 3-point position and the 1-point position of switch K1, short-circuit the 3-point position and the 1-point position of switch K2, and short-circuit the 3-point position and the 1-point position of switch K3, so that the test system works in the test mode; 5) The input terminal of the device under test is connected to N input signals in sequence, which are denoted as V INL 、V INL +ΔV*1, ..., V INL +ΔV*(N-2),V INH ; 6) The output end of the device under test outputs N output signals to the signal acquisition and analysis system in turn, which are recorded as V OS21 、V OS22 ,……,V OS2N ; 7) The signal acquisition and analysis system uses N input signals as the X-axis, subtracts the output signals of the two endpoints of the test mode and the calibration mode and connects them into a straight line as the ideal input-output straight line. The slope of the straight line is α = ((V OS2N -V OS1N )- (V OS21 -V OS11 )) / ( V INH -V INL ); 8) The signal acquisition and analysis system determines the value of the ideal input and output straight line projection on the Y axis, which are recorded as V OS31 、V OS32 ,……,V OS3N ; Among them, V OS31 =V INL *α, V OS32 =(V INL +ΔV*1)*α,……,V OS3N = V INH *α; 9) Calculate the deviations between the output signal of the device under test and the ideal input-output straight line in sequence, and record them as ΔE1, ΔE2, ..., ΔE N ; where ΔE1 = V OS21 -V OS11 -V OS31 , ΔE2 = V OS22 -V OS12 -V OS32 , ..., ΔE N = V OS2N -V OS1N -V OS3N ; 10) Calculate the nonlinearity h = (ΔE MAX -ΔE MIN ) / (2*G*( V INH -V INL ))*10 6 ; ΔE MAX , ΔE MIN are the maximum and minimum values ​​of the deviation respectively; G is the closed-loop gain of the auxiliary operational amplifier test device.

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