A method for verifying the adaptability of overshoot and ringing protection of rail-to-rail operational amplifiers

Abstract

A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier comprises the following steps: S1, using simulation software to build a rail-to-rail operational amplifier model, and connecting a capacitive load to the output end of the rail-to-rail operational amplifier; S2, inputting a square wave signal to the input end of the rail-to-rail operational amplifier, then simulating and recording the output waveform, and testing the output signal overshoot; S3, configuring a test board card identical to the simulation circuit, and recording the output waveform and signal overshoot; S4, adding a buffer composed of an R-C series network to the output end of the rail-to-rail operational amplifier; S5, after adding the buffer, comparing the output waveform and the output signal overshoot value before and after adding the buffer through simulation and actual measurement; S6, changing the frequency f of the input square wave signal, repeating S2 to S5, and verifying the inherent anti-overshoot performance and effective buffer parameter value of the rail-to-rail operational amplifier under different frequency conditions.

Description

Technical Field

[0001] The invention relates to a method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier, and belongs to the technical field of application verification. Background Art

[0002] The common-mode input voltage range or output voltage range of the rail-to-rail operational amplifier (hereinafter referred to as "rail-to-rail op amp") can reach from the positive power supply voltage rail to the negative power supply voltage rail, which effectively expands the dynamic range of the general operational amplifier, can maximize the input and output signal amplitude, increase the circuit signal-to-noise ratio, meet the application requirements of low voltage and low power consumption, and is increasingly used in the field of electronic technology. Due to its "to-rail" characteristics, rail-to-rail op amps are mostly used for operational conditioning of square wave or quasi-square wave signals. However, for imperfectly designed rail-to-rail op amps, since there is an output resistor inside, when the output end is connected to a capacitive load, an additional pole will be generated on the transfer function of the circuit, the amplitude-frequency response bandwidth will be narrowed, and the phase-frequency response will be extremely unstable. When conditioning square wave or quasi-square wave signals, large overshoot and ringing are likely to occur at the rising or falling edge of the output signal, causing signal distortion, and may also cause damage to the subsequent circuit. It is necessary to fully verify the inherent anti-overshoot and ringing capabilities of the rail-to-rail op amp. Summary of the invention

[0003] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier, to verify the inherent anti-overshoot performance of the rail-to-rail operational amplifier and the adaptability of the rail-to-rail operational amplifier after adding a buffer formed by an RC series network, and to provide a design reference for overshoot and ringing protection of rail-to-rail operational amplifier application circuits.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier comprises the following steps:

[0006] S1. Use simulation software to build the Spice model of the rail-to-rail operational amplifier. The output of the rail-to-rail operational amplifier is connected to a capacitive load C. L , determine the power supply voltage V according to the device manual S ;

[0007] S2, the input of the rail-to-rail operational amplifier is a square wave signal V with an amplitude of A and a frequency of f. in ;

[0008] S3. In the simulation software, record the output waveform and test the output signal overshoot OS 1 ;

[0009] S4. Configure the test board with the same simulation circuit and record the output waveform and signal overshoot OS 2 ;

[0010] S5. Add a buffer consisting of an RC series network at the output of the rail-to-rail operational amplifier, and adjust the resistance value of the buffer until the small signal transient response is optimal and the capacitance of the buffer is minimized while meeting the response performance conditions.

[0011] S6. After adding the buffer, repeat S2 to S4; compare the output waveform and output signal overshoot value before and after adding the buffer;

[0012] S7. Change the input signal frequency f and repeat S2 to S6 to verify the inherent anti-overshoot performance and effective buffer parameter values ​​of the rail-to-rail operational amplifier under different frequency conditions.

[0013] A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier comprises the following steps:

[0014] S10, using simulation software to build a rail-to-rail operational amplifier model, and connecting a capacitive load to the output of the rail-to-rail operational amplifier;

[0015] S20, inputting a square wave signal to the input end of the rail-to-rail operational amplifier, then simulating and recording the output waveform, and testing the output signal overshoot;

[0016] S30, configuring a test board that is the same as the simulation circuit, and recording the output waveform and signal overshoot;

[0017] S40, add a buffer composed of an RC series network at the output end of the rail-to-rail operational amplifier, and adjust the resistance value of the buffer until the small signal transient response is optimal and the capacitance of the buffer is minimized while meeting the response performance conditions;

[0018] S50, after adding the buffer, the output waveform and the output signal overshoot value before and after adding the buffer are compared through simulation and actual measurement to obtain the adaptability of the rail-to-rail operational amplifier to the RC series network buffer;

[0019] S60, changing the frequency f of the input square wave signal, repeating S20 to S50, and verifying the inherent anti-overshoot performance and effective buffer parameter values ​​of the rail-to-rail operational amplifier under different frequency conditions.

[0020] In one embodiment of the present invention, Multisim simulation software is used to perform Spice model stacking of a rail-to-rail operational amplifier.

[0021] In one embodiment of the present invention, the output terminal of the rail-to-rail operational amplifier is connected to the inverting input terminal to form a follower circuit.

[0022] In one embodiment of the present invention, the overshoot value is used to define the anti-overshoot performance of the device. The larger the overshoot value, the worse the anti-overshoot performance of the device, and the smaller the overshoot value, the better the anti-overshoot performance of the device.

[0023] In one embodiment of the present invention, the buffer is connected to the capacitive load C of the output terminal of S1. L For parallel relationship.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention proposes an evaluation method combining simulation and testing for the inherent anti-overshoot performance of a device in view of the overshoot and ringing phenomena that are prone to occur when a rail-to-rail operational amplifier is performing square wave or quasi-square wave signal conditioning, and adopts a buffer formed by adding an RC series network to verify the adaptability of the rail-to-rail operational amplifier to prevent overshoot and ringing. The method is a universal verification method that can be used to verify the anti-overshoot and ringing capabilities and protection adaptability of the rail-to-rail operational amplifier, and can also provide a reference for the design of application circuits for the rail-to-rail operational amplifier to prevent overshoot and ringing. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of the method of the present invention;

[0027] Figure 2 A schematic diagram of a follower circuit with a capacitive load connected to the output terminal as described in the present invention;

[0028] Figure 3 A schematic diagram of a follower circuit of a buffer network with an added RC series circuit as described in the present invention;

[0029] Figure 4 It is a schematic diagram of a typical rail-to-rail operational amplifier Spice macro model described in the present invention;

[0030] Figure 5 A schematic diagram of the circuit configuration described in the present invention;

[0031] Figure 6 A schematic diagram of a circuit configuration for adding an RC series circuit buffer network as described in the present invention;

[0032] Figure 7 It is a schematic diagram of the output waveform simulation and test described in the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier, the steps are as follows:

[0035] (1) Use simulation software to build a Spice model of a rail-to-rail operational amplifier, connect the rail-to-rail operational amplifier output terminal to the inverting input terminal to form a follower circuit, and connect the rail-to-rail operational amplifier output terminal to a capacitive load C L To the ground, such as Figure 2 As shown, determine the power supply voltage V according to the device manual S ;

[0036] (2) The input terminal inputs a square wave signal V with amplitude A and frequency f. in ;

[0037] (3) Use the set model to simulate, record the output waveform, and test the output signal overshoot OS 1 , the overshoot value is used to define the device's anti-overshoot performance. The larger the overshoot value, the worse the device's anti-overshoot performance, and the smaller the overshoot value, the better the device's anti-overshoot performance;

[0038] (4) Configure the same test board as the simulation circuit and record the output waveform and signal overshoot OS 2 ;

[0039] (5) Based on the model established in step (1), a buffer consisting of an RC series network is connected to ground at the output of the rail-to-rail op amp. The buffer is connected to the capacitive load C connected to the output in step (1). L For parallel relationship, such as Figure 3 As shown, R X The initial value is 100Ω, and then reduce this value until the small signal transient response is optimal. Set C X The initial value is 10μF. When the small signal transient response performance meets the application requirements, reduce this value until it cannot be reduced any further.

[0040] (6) Repeat steps (2) to (4);

[0041] (7) The output waveform and output signal overshoot value in steps (3) and (4) can effectively reflect the inherent anti-overshoot and ringing performance of the device; comparing the output waveform and output signal overshoot value before and after adding the buffer can effectively reflect the adaptability of the device to the RC series network buffer;

[0042] Change the input signal frequency f and repeat steps (2) to (7) to verify the inherent anti-overshoot performance and effective buffer parameter values ​​of the device under different frequency conditions.

[0043] Example:

[0044] like Figure 1 As shown, a method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier proposed by the present invention takes a certain type of rail-to-rail operational amplifier as an example, and the steps are as follows:

[0045] (1) A typical rail-to-rail op amp Spice macro model schematic is shown below Figure 4 As shown, Multisim simulation software is used to connect the rail-to-rail op amp output terminal and the inverting input terminal to form a follower circuit, as shown in Figure 5 As shown, the rail-to-rail op amp output is connected to the ground capacitive load C L The positive power supply voltage is 5V and the negative power supply voltage is grounded according to the device manual.

[0046] (2) Input amplitude 20mV P-P , square wave signal V with frequency f = 100KHz in ;

[0047] (3) Use the set Spice model to simulate and record the output waveform;

[0048] (4) Connect the output of the rail-to-rail op amp to the ground via a buffer consisting of a series RC network, such as Figure 6 As shown, R X =60Ω, C X =0.47μF;

[0049] (5) Input amplitude 20mV P-P , square wave signal V with frequency f = 100KHz in ;

[0050] (6) Use the established Spice model to perform simulation and record the output waveform after adding the buffer;

[0051] The output waveform before and after adding the buffer is as follows Figure 7 As shown (the upper curve is the output waveform after adding the buffer, and the lower curve is the output waveform without adding the buffer), analysis of the test waveform shows that the RC series buffer network can effectively increase the overshoot resistance of the device.

[0052] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

[0053] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier, characterized in that: The steps include: S1. Use simulation software to build the Spice model of the rail-to-rail operational amplifier. The output of the rail-to-rail operational amplifier is connected to a capacitive load C. L , determine the power supply voltage V according to the device manual S ; In S1, the rail-to-rail op amp output is connected to the inverting input to form a follower circuit; S2, the input of the rail-to-rail operational amplifier is a square wave signal V with an amplitude of A and a frequency of f. in ; S3. In the simulation software, record the output waveform and test the output signal overshoot OS1; S4, configure the test board same as the simulation circuit, and record the output waveform and signal overshoot OS2; S5. Add a buffer composed of an RC series network at the output of the rail-to-rail operational amplifier, and adjust the resistance value of the buffer until the small signal transient response is optimal and the capacitance of the buffer is minimized while meeting the response performance conditions. S6. After adding the buffer, repeat S2~S4; compare the output waveform and output signal overshoot value before and after adding the buffer; S7, change the input signal frequency f, repeat S2 to S6, and verify the inherent anti-overshoot performance and effective buffer parameter values ​​of the rail-to-rail operational amplifier under different frequency conditions; The overshoot value is used to define the device's anti-overshoot performance. The larger the overshoot value, the worse the device's anti-overshoot performance. The smaller the overshoot value, the better the device's anti-overshoot performance. Multisim simulation software is used to build the Spice model of the rail-to-rail operational amplifier.

2. The verification method according to claim 1, characterized in that: In S5, the buffer is connected to the capacitive load C at the output of S1. L For parallel relationship.

3. A method for verifying the adaptability of overshoot and ringing protection of a rail-to-rail operational amplifier, characterized in that: The steps include: S10, using simulation software to build a rail-to-rail operational amplifier model, and connecting a capacitive load to the output of the rail-to-rail operational amplifier; In S10, the rail-to-rail operational amplifier output terminal is connected to the inverting input terminal to form a follower circuit; S20, inputting a square wave signal to the input end of the rail-to-rail operational amplifier, then simulating and recording the output waveform, and testing the output signal overshoot; S30, configuring a test board that is the same as the simulation circuit, and recording the output waveform and signal overshoot; S40, add a buffer composed of an RC series network at the output end of the rail-to-rail operational amplifier, and adjust the resistance value of the buffer until the small signal transient response is optimal and the capacitance of the buffer is minimized while meeting the response performance conditions; S50, after adding the buffer, the output waveform and the output signal overshoot value before and after adding the buffer are compared through simulation and actual measurement to obtain the adaptability of the rail-to-rail operational amplifier to the RC series network buffer; S60, changing the frequency f of the input square wave signal, repeating S20 to S50, verifying the inherent anti-overshoot performance and effective buffer parameter values ​​of the rail-to-rail operational amplifier under different frequency conditions; Use Multisim simulation software to build the Spice model of rail-to-rail operational amplifier; The overshoot value is used to define the device's anti-overshoot performance. The larger the overshoot value, the worse the device's anti-overshoot performance. The smaller the overshoot value, the better the device's anti-overshoot performance.

4. The verification method according to claim 3, characterized in that: In S40, the buffer is connected to the capacitive load C at the output terminal of S10. L For parallel relationship.

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