Simple multi-parameter testing method for integrated operational amplifier

Abstract

The invention relates to a simple multi-parameter testing method for an integrated operational amplifier, which comprises the following steps of: 1) configuring the operational amplifier as a follower circuit, and short-circuiting the inverting input end of the operational amplifier and the output end VOUT; and 2) different excitation signals are respectively given to the in-phase input end VIN of the follower circuit, and parameters such as offset voltage VOS, quiescent current IQ, power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing VO, slew rate SR, setup time ST and unity gain bandwidth product UGBW are tested. According to the invention, a common operational amplifier is configured as a follower circuit, so that simple testing of parameters such as offset voltage VOS, quiescent current IQ, power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing VO, slew rate SR, establishment time ST, unity gain bandwidth product UGBW and the like can be completed.

Description

Technical Field

[0001] The invention belongs to the field of integrated circuit testing, and specifically relates to a simple, time-saving, low-cost and efficient integrated operational amplifier multi-parameter testing method, which implements the testing of the integrated operational amplifier multi-parameters through the most basic and least peripheral circuits. Background Art

[0002] Integrated operational amplifier circuits are the core of analog circuits, with wide applications and huge usage. However, due to the influence of its material properties, temperature characteristics, manufacturing process characteristics and other properties, there is a large error between the actual operational amplifier and the ideal operational amplifier parameter indicators. With the development of high precision, high speed, high bandwidth and low power consumption of operational amplifiers, the difficulty of testing and verification has gradually become more complicated. From the initial single operational amplifier test circuit to the dual operational amplifier loop and three operational amplifier loop test circuit, the test methods are becoming more and more complicated; for verification in actual applications, it is both time-consuming and costly. Summary of the invention

[0003] In order to solve the existing technical problems, the present invention provides a simple multi-parameter testing method for an integrated operational amplifier, which can verify whether the function of the operational amplifier circuit is normal without peripheral devices during the testing process.

[0004] The technical solution of the present invention is: the present invention is a simple multi-parameter testing method for an integrated operational amplifier, and its special feature is that the method comprises the following steps:

[0005] 1) Configure the operational amplifier as a follower circuit and connect the inverting input terminal of the operational amplifier to the output terminal V OUT Short circuit;

[0006] 2) Give the follower circuit's non-inverting input V IN Different excitation signals have different effects on the offset voltage V OS , Quiescent current I Q , power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing V O , slew rate SR, setup time ST, and unity gain bandwidth product UGBW parameters are tested.

[0007] Furthermore, the offset voltage V OS When the non-inverting input terminal V IN Connect to zero level and use a high-precision multimeter to measure the output terminal V OUT The magnitude of the offset voltage V OS .

[0008] Furthermore, the quiescent current I Q When measuring the offset voltage V OS At the same time, an ammeter can be connected in series to the power port to record the corresponding current value; that is, the static current I Q.

[0009] Furthermore, when testing the power supply rejection ratio (PSRR), the corresponding offset voltage under different power supplies is measured according to the power supply range required in the product manual. OS / ΔVsupply) formula to calculate the corresponding value.

[0010] Furthermore, when testing the maximum input voltage range IVR, by continuously changing the in-phase input terminal V IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change IN value.

[0011] Furthermore, the output voltage swing V O By continuously changing the non-inverting input terminal V IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change OUT value.

[0012] Furthermore, when testing the slew rate SR, a signal generator is used at the in-phase input terminal V IN Given a square wave signal of a certain frequency, use an oscilloscope to observe the waveform of the output port, select the middle part with smoother linearity and calculate the corresponding slew rate through ΔV / Δt.

[0013] Furthermore, when testing the setup time ST, in step 7) when testing the slew rate SR, use a signal generator to supply the same-phase input terminal V IN For a fixed frequency square wave signal, the time required from the input step signal to the output completely entering the specified error range observed by an oscilloscope is the setup time ST.

[0014] Furthermore, when testing the unit gain bandwidth product UGBW, a small sine wave signal with a constant amplitude is input to the in-phase input terminal V IN , change different frequencies and observe the output terminal V OUT When the voltage gain drops by 3dB, the non-inverting input terminal V IN The frequency corresponding to the constant amplitude, multiplied by the gain of 1, is the unity gain bandwidth product UGBW.

[0015] The present invention provides a simple multi-parameter testing method for an integrated operational amplifier, which can complete the offset voltage V by configuring a common operational amplifier as a follower circuit. OS , Quiescent current I Q , power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing V O, slew rate SR, settling time ST, unity gain bandwidth product UGBW and other parameters are tested simply. For the basic parameter test of these 8 op amps, only one follower circuit is needed to complete the verification of the basic functions of the op amp. The instruments used only need a high-precision voltage source, a high-precision oscilloscope, a high-precision multimeter and a signal generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a follower circuit diagram of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The simple multi-parameter testing method for integrated operational amplifiers of the present invention is preferably implemented by the following steps:

[0019] 1) For ordinary operational amplifiers, which generally have two-end input and one-end output, the present invention is based on Figure 1 Connect the inverting input of the operational amplifier to the output terminal V OUT short-circuited, configured as a follower circuit, respectively from the non-inverting input terminal V IN Given different excitation signals, measure the corresponding parameters: offset voltage V OS , Quiescent current I Q , power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing V O , slew rate SR, settling time ST, unity gain bandwidth product UGBW parameters;

[0020] 2) Offset voltage V OS The DC level loaded on the two input terminals of the op amp makes the output terminal zero. IN Connect to zero level and use a high-precision multimeter to measure the output terminal V OUT The size of is the offset voltage. When testing the offset voltage using this method, special attention should be paid to ensure that the chip and the fixture are in full contact and the cable length is as short as possible, that is, to ensure that the level of the in-phase input terminal is as close to the zero level as possible; the offset voltage measured using this method will not exceed 20% of the parameter index at most. If the measured value is inaccurate, please test the contact repeatedly;

[0021] 3) Quiescent current I Q Generally refers to the current consumed by the device when its output current is equal to 0. When measuring the offset voltage, an ammeter can be connected in series to the power supply end to record the corresponding current value; that is, the quiescent current I Q ;

[0022] 4) Power supply rejection ratio (PSRR) indicates the ability to suppress power supply changes. If the power supply of the operational amplifier changes, the output should not change in theory; but in practice it usually changes, which can also be understood as the change of offset voltage with the power supply. It is generally expressed as ΔV OS / ΔVsupply, the unit is μV / V; when expressed in dB, PSRR = -20log(ΔV OS / ΔVsupply). Generally, this parameter has specific power supply range requirements in the product manual. Measure the corresponding offset voltage under different power supplies and calculate it according to the above formula;

[0023] 5) Maximum input voltage IVR is the maximum input voltage range to ensure the normal operation of the operational amplifier, also known as the common-mode input voltage range. IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change IN value;

[0024] 6) Output voltage swing V O The maximum voltage range that the output can reach under given power supply voltage and load conditions. IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change OUT value;

[0025] 7) The slew rate SR is the fastest rate at which the output voltage of the closed-loop amplifier changes, generally expressed in V / μS. Use a signal generator to generate a voltage at the in-phase input terminal V IN Give a square wave signal of a certain frequency, use an oscilloscope to observe the waveform of the output port, select the smoother linear part in the middle and calculate the corresponding slew rate through ΔV / Δt;

[0026] 8) The setup time ST refers to the time required for the output to respond to a step change in the input and then enter and remain within the specified error. When testing the slew rate SR in step 7, use a signal generator to supply the same-phase input terminal V IN For a square wave signal with a fixed frequency, the time required from the input step signal to the output completely entering the specified error range is the setup time ST.

[0027] 9) The unit gain bandwidth product UGBW is the frequency corresponding to the constant amplitude observed from the OUT output when a small sine wave signal with a constant amplitude is input to the non-inverting input terminal under the condition that the closed-loop gain is 1 and the frequency is changed to 0.707 times (voltage gain drops by 3dB) when the constant amplitude is observed from the OUT output terminal. During the test, a small sine wave signal with a constant amplitude is input to the non-inverting input terminal VIN , change different frequencies, observe the frequency corresponding to the constant amplitude of the input end when the OUT output is equal to 0.707 times (the voltage gain drops by 3dB), and multiply it by the gain of 1 to get the unit gain bandwidth product UGBW.

[0028] The above are only specific embodiments disclosed in the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

[0029] The content of the present invention and the technical content not specifically described in the above embodiments are the same as the prior art.

[0030] The present invention is not limited to the above embodiments, and all of the contents of the present invention can be implemented and have the above good effects.

Claims

1. A simple multi-parameter test method for an integrated operational amplifier, characterized in that: The method comprises the following steps: 1) Configure the operational amplifier as a follower circuit and connect the inverting input terminal of the operational amplifier to the output terminal V OUT Short circuit; 2) Give the follower circuit's non-inverting input V IN Different excitation signals have different effects on the offset voltage V OS , Quiescent current I Q , power supply rejection ratio PSRR, maximum input voltage range IVR, output voltage swing V O , slew rate SR, setup time ST, and unity gain bandwidth product UGBW parameters are tested.

2. The simple multi-parameter testing method for an operational amplifier according to claim 1, characterized in that: Test offset voltage V OS When the non-inverting input terminal V IN Connect to zero level and use a high-precision multimeter to measure the output terminal V OUT The magnitude of the offset voltage V OS .

3. The simple multi-parameter testing method for an operational amplifier according to claim 2, characterized in that: Test quiescent current I Q When measuring the offset voltage V OS At the same time, an ammeter can be connected in series to the power port to record the corresponding current value; that is, the static current I Q .

4. The simple multi-parameter testing method for an operational amplifier according to claim 2, characterized in that: When testing the power supply rejection ratio (PSRR), measure the corresponding offset voltage under different power supplies according to the power supply range required in the product manual. OS / ΔVsupply) formula to calculate the corresponding value.

5. The simple multi-parameter testing method for an operational amplifier according to claim 1, characterized in that: When testing the maximum input voltage range IVR, the non-inverting input terminal V IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change IN value.

6. The simple multi-parameter testing method for an operational amplifier according to claim 1, characterized in that: Test output voltage swing V O By continuously changing the non-inverting input terminal V IN Observe the voltage at the output terminal V OUT Whether it changes linearly, record the V before the nonlinear change OUT value.

7. The simple multi-parameter testing method for an operational amplifier according to claim 1, characterized in that: When testing the slew rate SR, use a signal generator to input V IN Given a square wave signal of a certain frequency, use an oscilloscope to observe the waveform of the output port, select the middle part with smoother linearity and calculate the corresponding slew rate through ΔV / Δt.

8. The simple multi-parameter testing method for an operational amplifier according to claim 7, characterized in that: When testing the setup time ST, use a signal generator to supply the same-phase input terminal V IN For a fixed frequency square wave signal, the time required from the input step signal to the output completely entering the specified error range observed by an oscilloscope is the setup time ST.

9. The simple multi-parameter testing method for an operational amplifier according to claim 1, characterized in that: When testing the unity gain bandwidth product UGBW, a small sine wave signal with a constant amplitude is input to the non-inverting input terminal V IN , change different frequencies and observe the output V OUT When the voltage gain drops by 3dB, the non-inverting input terminal V IN The frequency corresponding to the constant amplitude, multiplied by the gain of 1, is the unity gain bandwidth product UGBW.

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