A method and device for quantitatively characterizing the application characteristics of an amplifier

Abstract

The application provides a quantitative characterization method of amplifier application characteristics, comprising the following steps: sampling input signals and output signals of an amplifier in a working state in an application circuit; extracting input and output sampling sequences to perform correlation analysis and calculate application characteristic distortion of the amplifier; shifting the output sampling sequence, and obtaining application characteristic distortion and phase shift of the amplifier in a current application state by calculating the application characteristic distortion in different shift states; and realizing quantitative characterization of the application characteristics of the amplifier in different application states by changing the application states. The application also provides a quantitative characterization device of amplifier application characteristics, comprising an input signal acquisition card, an output signal acquisition card, a correlation analysis and application characteristic distortion calculation processing unit and a display output unit. The application characterizes the application characteristics of the amplifier by the application characteristic distortion, which is more intuitive and effective compared with the indirect reflection of the application characteristics by the electrical performance parameters of the device.

Description

Technical Field

[0001] This invention belongs to the field of amplifier testing technology, and specifically relates to a quantitative characterization method and apparatus for amplifier application characteristics. Background Technology

[0002] As a commonly used electronic component, the application characteristics of amplifiers are of particular concern to application designers. In practical applications, there are problems such as amplifier parameters being out of tolerance not necessarily being "unusable" and performance parameters being qualified not necessarily being "easy to use". In order to truly solve the problem of whether a device is usable and whether it is easy to use under application conditions, it is found that only by finding a characterization method that indicates the performance of the device under application conditions and quantifying it is meaningful.

[0003] Because amplifiers generally operate in a non-ideal amplification state in practical applications, exhibiting varying degrees of nonlinearity, the signals used will have their useful information properties altered to some extent when passing through a system composed of these amplifiers. This change is known as signal distortion. Quantitatively characterizing the application characteristics of an amplifier using characteristic distortion is tailored to the specific needs of amplifier applications.

[0004] Distortion detection methods are mainly divided into fundamental frequency suppression and spectral analysis. Analog distortion meters generally use fundamental frequency suppression, but this method is expensive and has a short lifespan; once the hardware ages, the measurement accuracy will be significantly reduced. Spectral analysis is currently the main analysis method used by digital distortion meters. Its principle is to perform a Fast Fourier Transform (FFT) on the test signal and then calculate the distortion based on the power spectrum relationship between the fundamental frequency and other harmonics. This spectral analysis method suffers from spectral leakage and the picket-fence effect. Without any processing, the error is quite large. The common practice now is to control the effect of spectral leakage by windowing. This reduces the impact of error but does not eliminate spectral leakage. Another method is to adjust the sampling rate to synchronize the signal's fundamental frequency with the sampling frequency; that is, during the FFT transformation, ensure that the captured time-domain waveform is an integer multiple of the period. However, this approach increases hardware complexity and also suffers from hardware aging. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a quantitative characterization method and apparatus for amplifier application characteristics, thereby solving the problem that the inaccurate reflection of amplifier application characteristics indirectly through the testing of amplifier electrical performance parameters is not possible.

[0006] The technical solution of this invention is:

[0007] A quantitative characterization method for amplifier application characteristics includes the following steps:

[0008] (1) Connect the amplifier under test to the application circuit and turn on the application circuit to put the amplifier under test into working state.

[0009] (2) The input and output signals of the amplifier under test are sampled synchronously at the same sampling frequency to obtain the sampled data of the input and output signals;

[0010] (3) Remove abnormal sampling data points, extract continuous input signal sampling sequences and corresponding output signal sampling sequences from the sampling data, and the remaining sampling data after extraction shall contain at least one sampling data point of the length of a signal period that is continuous with the tail of the extracted sampling sequence.

[0011] (4) Calculate the correlation coefficient R between the extracted input signal sampling sequence and the output signal sampling sequence;

[0012] (5) Calculate the application characteristic distortion D of the amplifier under test based on the correlation coefficient;

[0013] (6) Based on step (3), the selected input signal sampling sequence remains unchanged. The selected output signal sampling sequence is shifted backward N-1 times with a step size of 1 sampling data point. After each shift, steps (4) and (5) are repeated to obtain D0, D1...D j ...D N-1 D j The distortion of the application characteristics after moving j sampling data points, j = 0, 1...N-1, where N represents the number of sampling data points of one signal period;

[0014] (7) Calculate D0, D1...D N-1 The absolute value, the minimum absolute value D MIN As the application characteristic distortion of the amplifier under test in the current application state;

[0015] (8) According to D MIN The phase shift of the amplifier under test is calculated by the number of shifts and the sampling frequency of the corresponding output signal sampling sequence.

[0016] (9) Change the application state of the amplifier under test and repeat steps (1) to (8) to obtain the application characteristic distortion and phase shift of the amplifier under test under different application states. Analyze the application performance of the amplifier under test based on the application characteristic distortion and phase shift.

[0017] Preferably, the correlation coefficient R is calculated using the following expression:

[0018]

[0019] Among them, X i Yi Let i = 1, 2, 3, ..., n, where n is the number of sampled data points for the input and output signals, respectively. These are the average values ​​of n sampled data points for the input signal and the output signal, respectively.

[0020] Preferably, the application characteristic distortion D is calculated using the following expression:

[0021]

[0022] Preferably, in step (9), the application performance of the amplifier under test is analyzed based on the application characteristic distortion and phase shift, specifically: when D MIN When ≤1, the application performance of the amplifier under test is normal; otherwise, the application performance of the amplifier under test is abnormal, and D MIN The larger the value of D, the worse the application performance of the amplifier under test. MIN When the phase shift is 0, the amplifier under test is in an ideal working state; the larger the phase shift, the worse the application performance of the amplifier under test. When the phase shift is 0, the amplifier under test is in an ideal working state.

[0023] Preferably, in step (2), the sampled data includes at least three sampled data points with a signal cycle length.

[0024] Preferably, in step (3), the extracted sampling sequence includes at least two sampling data points with a signal period length.

[0025] Preferably, the application state includes, but is not limited to: the frequency of the input signal, the amplitude of the input signal, the ambient temperature of the application, and the ambient radiation intensity of the application.

[0026] A quantitative characterization device for amplifier application characteristics includes an input signal acquisition card, an output signal acquisition card, a correlation analysis and application characteristic distortion calculation processing unit, and a display output unit. The input signal acquisition card and the output signal acquisition card synchronously sample the input signal and output signal of the amplifier under test at the same sampling frequency to acquire the sampled data of the input signal and output signal. The correlation analysis and application characteristic distortion calculation processing unit calculates the application characteristic distortion and phase shift of the amplifier based on the sampled data. The display output unit displays the calculated application characteristic distortion and phase shift.

[0027] Preferably, the correlation analysis and application characteristic distortion calculation processing unit calculates the application characteristic distortion and phase shift of the amplifier based on the sampled data, specifically: removing abnormal sampled data points, extracting a continuous input signal sampling sequence and its corresponding output signal sampling sequence from the sampled data, wherein the remaining sampled data after extraction contains at least one signal period length of sampled data points that are continuous with the tail of the extracted sampled sequence, and the extracted sampled sequence contains at least two signal period lengths of sampled data points;

[0028] Calculate the correlation coefficient R between the extracted input signal sampling sequence and the output signal sampling sequence:

[0029]

[0030] Among them, X i Y i Let i = 1, 2, 3, ..., n, where n is the number of sampled data points for the input and output signals, respectively. These are the average values ​​of n sampled data points for the input signal and the output signal, respectively.

[0031] Calculate the application characteristic distortion D of the amplifier under test based on the correlation coefficient:

[0032]

[0033] The selected input signal sampling sequence remains unchanged. The selected output signal sampling sequence is shifted backward N-1 times with a step size of 1 sampling data point. After each shift, the applied characteristic distortion is calculated to obtain D0, D1...D j ...D N-1 D j The distortion of the application characteristics after moving j sampling data points, j = 0, 1...N-1, where N represents the number of sampling data points of one signal period;

[0034] Calculate D0, D1...D N-1 The absolute value, the minimum absolute value D MIN As the application characteristic distortion of the amplifier under test in the current application state;

[0035] According to D MIN The phase shift of the amplifier under test is calculated by the number of shifts and the sampling frequency of the corresponding output signal sampling sequence.

[0036] Preferably, the input signal acquisition card and the output signal acquisition card acquire input signal and output signal sampling data including at least 3 sampling data points with a signal cycle length.

[0037] The advantages of this invention compared to the prior art are:

[0038] (1) This invention quantitatively reflects the amplification application characteristics of an amplifier by applying characteristic distortion, which is more intuitive and effective than the amplifier's electrical performance parameters indirectly reflecting the application characteristics.

[0039] (2) This invention analyzes the input and output signals directly through the application circuit to obtain quantitative characterization of amplification characteristics and parameters such as delay or phase shift under different working conditions. It can be extended to quantitative characterization of application characteristics that change with the environment, rather than the characteristics of individual electrical performance parameters. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the quantitative characterization method for amplifier application characteristics according to the present invention;

[0041] Figure 2 This is a schematic diagram illustrating the working principle of the amplifier application characteristic quantitative characterization device according to an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of the amplifier quantitative characterization process based on a quantitative characterization device according to an embodiment of the present invention;

[0043] Figure 4 This is a schematic diagram of the waveforms of the input and output signal sampling data points in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram illustrating the distortion characteristics of the amplifier at different frequencies according to an embodiment of the present invention. Detailed Implementation

[0045] The features and advantages of the present invention will become clearer and more explicit through the following detailed description.

[0046] This invention provides a method and apparatus for quantitatively characterizing the application characteristics of an amplifier. The method includes: by analyzing the correlation between the input and output signals of the amplifier under application conditions, and based on the correlation coefficient, proposing the Wenyan equation to characterize the distortion of the amplifier's application characteristics under application conditions, and quantitatively characterizing the amplifier's application characteristics through the distortion of application characteristics; the apparatus includes an input signal acquisition card, an output signal acquisition card, a correlation analysis and application characteristic distortion calculation and processing unit, and a display output unit.

[0047] A quantitative characterization method for amplifier application characteristics, such as Figure 1 As shown, the steps are as follows:

[0048] 1) Connect the amplifier under test to the application circuit and turn on the application circuit to put the amplifier under test into working condition;

[0049] 2) The input and output signals of the amplifier under test are synchronously sampled at the same sampling frequency to obtain the sampled data of the input and output signals; the sampled data shall include at least 3 sampling data points with a signal cycle length;

[0050] 3) Remove abnormal sampling data points, extract continuous input signal sampling sequences and their corresponding output signal sampling sequences from the sampling data, and the remaining sampling data after extraction shall contain at least one sampling data point of one signal period length that is continuous with the tail of the extracted sampling sequence; the extracted sampling sequence shall contain at least two sampling data points of two signal period lengths.

[0051] 4) Calculate the correlation coefficient R between the extracted input signal sampling sequence and the output signal sampling sequence;

[0052] The correlation coefficient R is expressed by the formula:

[0053]

[0054] The calculation yields, where X i Y i Let i = 1, 2, 3, ..., n, where n is the number of sampling points covering at least two input signal periods. These are the average values ​​of n sampled data points for the input and output signals, respectively.

[0055] 5) Calculate the application characteristic distortion D of the amplifier under test based on the correlation coefficient;

[0056] The applied characteristic distortion D is obtained using the Wenyan equation. The Wenyan equation is defined as follows:

[0057]

[0058] Here, D is defined as the application characteristic distortion of the device, and R is the correlation coefficient, with a value range of [-1, 1]. When 0 ≤ R ≤ 1, the corresponding value range of D is (+∞, 0]; when -1 ≤ R ≤ 0, the corresponding value range of D is [0, -∞). For amplifiers, the application characteristic distortion D represents the amplifier's application characteristic distortion, and has the following characteristics:

[0059] (a) The larger the absolute value of D, the greater the distortion of the amplifier's application characteristics, indicating a worse amplification characteristic;

[0060] (b) D > 0 indicates that the amplifier is operating in the forward amplification state, and D < 0 indicates that the amplifier is operating in the reverse amplification state;

[0061] (c) D = 0 means that the amplifier's characteristic distortion is 0, indicating that there is no distortion and the amplifier is working in an ideal state.

[0062] Generally, when |D|≤1, the amplifier's application characteristic distortion is small, indicating that the amplifier's application performance is normal; otherwise, it indicates that the amplifier's application performance is abnormal.

[0063] 6) Based on step 3), the selected input signal sampling sequence remains unchanged. The selected output signal sampling sequence is shifted backward N-1 times with a step size of 1 sampling data point. After each shift, steps 4) and 5) are repeated to obtain D0, D1...D j ...D N-1 D j The distortion of the application characteristics after moving j sampling data points, j = 0, 1...N-1, where N represents the number of sampling data points of one signal period;

[0064] 7) Calculate D0, D1...D N-1 The absolute value, the minimum absolute value D MIN As the application characteristic distortion of the amplifier under test in the current application state;

[0065] 8) According to D MIN The phase shift of the amplifier under test is calculated by the number of shifts and the sampling frequency of the corresponding output signal sampling sequence.

[0066] 9) Change the application state of the amplifier under test and repeat steps 1) to 8) to obtain the application characteristic distortion and phase shift of the amplifier under test under different application states. Analyze the application performance of the amplifier under test based on the application characteristic distortion and phase shift.

[0067] Application status includes, but is not limited to: the frequency of the input signal, the amplitude of the input signal, the ambient temperature of the application, and the ambient radiation intensity of the application.

[0068] Example

[0069] like Figure 2 As shown, the application characteristic quantitative characterization device includes: an input signal acquisition card, an output signal acquisition card, a correlation analysis and application characteristic distortion calculation and processing unit, and a display output unit; the typical application circuit consists of a non-inverting proportional amplifier circuit, including amplifier A, input signal, non-inverting input resistor R1, inverting input resistor R2, and feedback resistor R... f and output load R L .

[0070] In an ideal scenario, the input signal V in a typical application circuit i With output signal V o The relationship between them is:

[0071]

[0072] Output signal V o With input signal V i There is a linear relationship between them, with a correlation coefficient R of 1, and the applied characteristic distortion D is 0, indicating no distortion, i.e., the best amplification characteristics. However, considering the frequency characteristics of op-amp A and the non-ideal amplification state, the output signal V o Relative to the input signal V i There may be delays, phase shifts, or distortion.

[0073] The process of quantitatively characterizing amplifier application characteristics using the quantitative characterization device of this invention is as follows: Figure 3 As shown, it includes:

[0074] S1 confirms the application status of the amplifier based on typical application circuits. Confirming the application status of the amplifier includes confirming whether the input signal, output load, and power supply status are within the range specified in the amplifier manual.

[0075] S2 locates the input and output signal detection points;

[0076] S3 connects the input and output signal acquisition cards of the quantitative characterization device to the input and output signal detection points, respectively.

[0077] S4 first connects the power supply to the application circuit to put the amplifier into operation; then it connects the power supply to the quantitative characterization device for the application characteristics to start collecting input and output signals and collect data for more than 3 cycles.

[0078] S5 processes the collected input and output signal data, removes abnormal data points, and selects data points from at least two cycles for input and output signal calculation.

[0079] S6 calculates the correlation coefficient R between the input signal and the output signal;

[0080] S7 calculates the application characteristics of the amplifier, specifically the distortion D.

[0081] S8 shifts the sampling points of the output signal and calculates the application characteristic distortion for each point, thus obtaining the application characteristic distortion D of the amplifier under the current input signal application state. MIN Through sampling rate and D MIN The corresponding input signal sampling point shift interval can be used to calculate the delay or phase shift; and the values ​​of amplifier application characteristic distortion and delay or phase difference for a specific operating state (such as operating frequency) are displayed on the display output unit, thereby quantitatively characterizing the amplification characteristics of amplifier A;

[0082] S9 changes the amplifier's application state, such as the frequency of the input signal, to obtain the application characteristics of distortion, delay, or phase shift under different application states (such as different operating frequencies). The application characteristics of the amplifier are quantitatively characterized by distortion and phase shift.

[0083] In this embodiment, amplifier A in the typical application circuit is selected as SF2512D manufactured by a certain company, R1 is selected as 3K ohms 0.25W, R2 is selected as 5K ohms 0.25W, R... f Choosing a 6.4K ohm 0.25W amplifier, the input signal V under ideal conditions will be... i With output signal V o The relationship between them is:

[0084]

[0085] That is, with a magnification factor of 2.27 and the power supply voltage of the SF2512D amplifier set to ±15V, when the input signal is a sine wave with an amplitude of 3.3V and a frequency of 10kHz, and the sampling rate of the input and output signal sampling card is 0.5μs / point, a total of 1402 points were sampled. The waveforms of the input and output signals at the sampled points are shown below. Figure 4 As shown, the minimum value D calculated according to the above steps MIN The value is 0.064765049. At this point, the output signal calculation point is shifted by 26 sampling points relative to the input signal, which means a delay of 26 × 0.5 μs / point = 13 μs. The phase shift of the output signal is 46.8°.

[0086] By changing the operating frequency of the input signal, the amplification performance, distortion, and phase shift of the output are displayed at different frequencies using a quantitative characterization device, as shown in Table 1.

[0087] Table 1. Amplifier application characteristics (distortion and phase shift) at different frequencies in the embodiments of the present invention.

[0088]

[0089] The characteristic distortion curves of the amplifier at different frequencies are as follows: Figure 5 As shown in the figure, the amplifier has the lowest characteristic distortion when operating at 10kHz, indicating the best amplification performance at this operating frequency, but the phase shift reaches 46.8°. The amplification performance distortion is less than 1 in the test frequency range, indicating that the amplifier works normally in this frequency range. There is a significant phase shift after the operating frequency of 800Hz, and the phase shift increases with the increase of frequency.

[0090] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A quantitative characterization method for amplifier application characteristics, characterized in that, Includes the following steps: (1) Connect the amplifier under test to the application circuit and turn on the application circuit to put the amplifier under test into working state. (2) The input and output signals of the amplifier under test are sampled synchronously at the same sampling frequency to obtain the sampled data of the input and output signals; (3) Remove abnormal sampling data points, extract continuous input signal sampling sequences and corresponding output signal sampling sequences from the sampling data, and the remaining sampling data after extraction shall contain at least one sampling data point that is continuous with the tail of the extracted sampling sequence for one signal period. (4) Calculate the correlation coefficient R between the extracted input signal sampling sequence and the output signal sampling sequence; (5) Calculate the application characteristic distortion D of the amplifier under test based on the correlation coefficient; (6) Based on step (3), the selected input signal sampling sequence remains unchanged. The selected output signal sampling sequence is shifted backward N-1 times with a step size of 1 sampling data point. After each shift, steps (4) and (5) are repeated to obtain D0, D1...D j ...D N-1 D j The distortion of the application characteristics after moving j sampling data points, j = 0, 1...N-1, where N represents the number of sampling data points of one signal period; (7) Calculate D0, D1...D N-1 The absolute value, the minimum absolute value D MIN As the application characteristic distortion of the amplifier under test in the current application state; (8) According to D MIN The phase shift of the amplifier under test is calculated by the number of shifts and the sampling frequency of the corresponding output signal sampling sequence. (9) Change the application state of the amplifier under test and repeat steps (1) to (8) to obtain the application characteristic distortion and phase shift of the amplifier under test under different application states. Analyze the application performance of the amplifier under test based on the application characteristic distortion and phase shift. The application characteristic distortion D is calculated using the following expression:

2. The quantitative characterization method for amplifier application characteristics according to claim 1, characterized in that, The correlation coefficient R is calculated using the following expression: Among them, X i Y i Let i = 1, 2, 3, ..., n, where n is the number of sampled data points for the input and output signals, respectively. These are the average values ​​of n sampled data points for the input signal and the output signal, respectively.

3. The quantitative characterization method for amplifier application characteristics according to claim 2, characterized in that, In step (9), the application performance of the amplifier under test is analyzed based on the application characteristic distortion and phase shift, specifically: when D MIN When ≤1, the application performance of the amplifier under test is normal; otherwise, the application performance of the amplifier under test is abnormal, and D MIN The larger the value of D, the worse the application performance of the amplifier under test. MIN When the phase shift is 0, the amplifier under test is in an ideal working state; the larger the phase shift, the worse the application performance of the amplifier under test. When the phase shift is 0, the amplifier under test is in an ideal working state.

4. The quantitative characterization method for amplifier application characteristics according to claim 3, characterized in that, In step (2), the sampled data includes at least three sampled data points with a signal cycle length.

5. The quantitative characterization method for amplifier application characteristics according to claim 4, characterized in that, In step (3), the extracted sampling sequence includes at least two sampling data points with a signal period length.

6. A quantitative characterization method for amplifier application characteristics according to any one of claims 1 to 5, characterized in that, The application status includes the frequency of the input signal, the amplitude of the input signal, the ambient temperature of the application, and the ambient radiation intensity of the application.

7. A quantitative characterization device for amplifier application characteristics, characterized in that, The system includes an input signal acquisition card, an output signal acquisition card, a correlation analysis and application characteristic distortion calculation processing unit, and a display output unit. The input signal acquisition card and the output signal acquisition card synchronously sample the input and output signals of the amplifier under test at the same sampling frequency to acquire the sampled data of the input and output signals. The correlation analysis and application characteristic distortion calculation processing unit calculates the application characteristic distortion and phase shift of the amplifier based on the sampled data. The display output unit displays the calculated application characteristic distortion and phase shift. The related analysis and application characteristic distortion calculation processing unit calculates the application characteristic distortion and phase shift of the amplifier based on the sampled data. Specifically, it removes abnormal sampled data points, extracts a continuous input signal sampling sequence and its corresponding output signal sampling sequence from the sampled data, and the remaining sampled data after extraction contains at least one signal period length of sampled data points that are continuous with the tail of the extracted sampled sequence. The extracted sampled sequence contains at least two signal period lengths of sampled data points. Calculate the correlation coefficient R between the extracted input signal sampling sequence and the output signal sampling sequence: Among them, X i Y i Let i = 1, 2, 3, ..., n, where n is the number of sampled data points for the input and output signals, respectively. These are the average values ​​of n sampled data points for the input signal and the output signal, respectively. Calculate the application characteristic distortion D of the amplifier under test based on the correlation coefficient: The selected input signal sampling sequence remains unchanged. The selected output signal sampling sequence is shifted backward N-1 times with a step size of 1 sampling data point. After each shift, the applied characteristic distortion is calculated to obtain D0, D1...D j ...D N-1 D j The distortion of the application characteristics after moving j sampling data points, j = 0, 1...N-1, where N represents the number of sampling data points of one signal period; Calculate D0, D1...D N-1 The absolute value, the minimum absolute value D MIN As the application characteristic distortion of the amplifier under test in the current application state; According to D MIN The phase shift of the amplifier under test is calculated by the number of shifts and the sampling frequency of the corresponding output signal sampling sequence.

8. The quantitative characterization device for amplifier application characteristics according to claim 7, characterized in that, The input signal acquisition card and the output signal acquisition card acquire input signal and output signal sampling data including at least 3 signal cycle lengths of sampling data points.

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