Arbitrary wave generator predistortion method

Abstract

The invention discloses a predistortion method for an arbitrary wave generator. The predistortion method for the arbitrary wave generator comprises the following steps: acquiring a time domain pulse step response signal output by the arbitrary wave generator; establishing a time domain distortion model according to the time domain pulse step response signal; and correcting a distortion signal of a long-time overshoot type in the time domain pulse step response signal according to a time domain distortion model to obtain a first pre-distortion signal. Therefore, through the method, the predistortion response can be obtained by measuring the time domain pulse step response signal of the arbitrary wave generator, and compared with the traditional direct measurement of the frequency response of the system, the measurement mode is simpler and more convenient. The time domain distortion model is established, the long-time overshoot type distorted signals can be corrected through the time domain distortion model, and compared with an existing mode, the correction effect is good, and the calculated amount is small.

Description

Technical Field

[0001] The invention relates to the technical field of precision testing and measurement, and in particular to a predistortion method for an arbitrary wave generator. Background Art

[0002] As a general electronic instrument, the arbitrary wave generator can generate various real waveforms and excitation signals, and has a wide range of uses in modern electronic test and measurement, electronic simulation and other fields. However, due to many non-ideal characteristics in the entire hardware link from the analog circuit of the arbitrary wave generator to the load end, such as amplifier ringing, parasitic capacitance and parasitic inductance in the line, impedance mismatch, etc., the output signal of the arbitrary wave generator has different degrees of distortion when it reaches the load end, including ringing, overshoot, reflection standing wave, etc. These distortions are often unacceptable in some precision electronic test and measurement applications.

[0003] At present, the waveform pre-distortion method is often used to reduce the waveform distortion caused by the non-ideal characteristics of the hardware link. The basic principle of this waveform pre-distortion method is to first obtain the frequency domain response of the link through measurement, and then take the inverse of the frequency domain response as the response of the pre-distortion processing. The original waveform of the arbitrary waveform generator is first subjected to the pre-distortion processing before being output, and then this part of the non-ideal characteristics will be offset when passing through the actual link, thereby reducing the waveform distortion when it reaches the load end. However, this method has the disadvantages of large measurement and calculation amount and poor correction effect of long-term overshoot distortion. Summary of the invention

[0004] The invention provides an arbitrary wave generator predistortion method to realize correction of a long-time overshoot type distorted signal, and the method has simple measurement, small calculation amount and good correction effect.

[0005] According to one aspect of the present invention, there is provided an arbitrary wave generator predistortion method, the arbitrary wave generator predistortion method comprising:

[0006] Acquire a time-domain pulse step response signal output by the arbitrary wave generator;

[0007] Establishing a time domain distortion model according to the time domain pulse step response signal;

[0008] A long-time overshoot type distortion signal in the time-domain impulse step response signal is corrected according to the time-domain distortion model to obtain a first predistortion signal.

[0009] Optionally, the correcting a long-time overshoot type distortion signal in the time-domain impulse step response signal according to the time-domain distortion model includes:

[0010] Obtaining a first-order IIR filter according to the time domain distortion model;

[0011] Obtaining distortion model parameters of a first-order IIR filter according to the time-domain impulse step response signal and the time-domain distortion model;

[0012] A long-time overshoot type distortion signal in the time-domain impulse step response signal is corrected according to the distortion model parameters of the first-order IIR filter and the first-order IIR filter.

[0013] Optionally, obtaining a first-order IIR filter according to the time domain distortion model includes:

[0014] The time domain distortion model is subjected to Laplace transformation, predistortion transformation and bilinear transformation in sequence to obtain a first-order IIR filter.

[0015] Optionally, obtaining distortion model parameters of a first-order IIR filter according to the time-domain impulse step response signal and the time-domain distortion model includes:

[0016] The time domain impulse step response signal and the time domain distortion model are fitted to obtain distortion model parameters of a first-order IIR filter.

[0017] Optionally, the distortion model parameters of the first-order IIR filter include the amplitude and time constant of the distortion signal.

[0018] Optionally, the correcting a long-time overshoot type distortion signal in the time-domain impulse step response signal according to a distortion model parameter of a first-order IIR filter and the first-order IIR filter comprises:

[0019] The distortion model parameters of the first-order IIR filter are input into the first-order IIR filter to compensate for the long-term overshoot type distortion signal in the time-domain impulse step response signal.

[0020] Optionally, the time domain distortion model is:

[0021] y(t)=(1+Ae -t / τ )·u(t)

[0022] Where y(t) is the voltage across the load, u(t) is the step response, A is the amplitude of the distorted signal, and τ is the time constant of the distorted signal.

[0023] Optionally, after correcting the long-time overshoot type distortion signal in the time-domain impulse step response signal according to the time-domain distortion model to obtain the first predistortion signal, the method further includes:

[0024] performing a differential operation on the first predistortion signal to obtain an impulse response;

[0025] A predistorted impulse response is obtained according to the impulse response and the unit impulse function;

[0026] The first predistortion signal is predistorted according to the predistortion impulse response to obtain a second predistortion signal.

[0027] Optionally, before performing a differential operation on the first predistortion signal, the method further includes:

[0028] Normalization processing is performed on the first predistortion signal.

[0029] Optionally, obtaining the predistorted impulse response according to the impulse response and the unit impulse function includes: obtaining the predistorted impulse response according to the impulse response and the unit impulse function using an L2 regularization method;

[0030] The predistortion processing is performed on the first predistortion signal according to the predistortion impulse response to obtain the second predistortion signal, including: using the predistortion impulse response as a coefficient of an FIR filter, and predistortion processing is performed on the first predistortion signal according to the FIR filter to obtain the second predistortion signal.

[0031] The technical solution of the embodiment of the present invention provides an arbitrary wave generator predistortion method, which includes: obtaining a time domain pulse step response signal output by the arbitrary wave generator; establishing a time domain distortion model according to the time domain pulse step response signal; and correcting the long-time overshoot type distortion signal in the time domain pulse step response signal according to the time domain distortion model to obtain a first predistortion signal. It can be seen that this method can achieve: obtaining the predistortion response by measuring the time domain pulse step response signal of the arbitrary wave generator, and the measurement method is simpler than the traditional direct measurement system frequency response. And by establishing a time domain distortion model, and by using the time domain distortion model, it is possible to correct the long-time overshoot type distortion signal, and compared with the existing method, the correction effect is good and the calculation amount is small.

[0032] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is a flow chart of an arbitrary wave generator predistortion method provided in an embodiment of the present invention;

[0035] Figure 2 is a schematic diagram of a distorted waveform collected by an oscilloscope provided in an embodiment of the present invention;

[0036] Figure 3 It is provided in the embodiment of the present invention Figure 2 A partial enlarged view of the

[0037] Figure 4 Schematic diagram of the circuit structure of an arbitrary wave generator and a load provided in an embodiment of the present invention;

[0038] Figure 5 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention;

[0039] Figure 6 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention;

[0040] Figure 7 It is a schematic diagram of fitting a time domain pulse step response signal and a time domain distortion model provided in an embodiment of the present invention;

[0041] Figure 8 is a schematic diagram of a signal waveform after being pre-distorted by a first-order IIR filter provided in an embodiment of the present invention;

[0042] Fig. 9 It is provided in the embodiment of the present invention Figure 8 A partial enlarged view of

[0043] Fig.10 is a schematic diagram of a waveform after being pre-distorted by multiple IIR filters provided in an embodiment of the present invention;

[0044] Fig.11 It is provided in the embodiment of the present invention Fig.10 A partial enlarged view of

[0045] Fig.12 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention;

[0046] Fig.13 is a schematic diagram of a distorted signal with a relatively short residual time after being pre-distorted by a first-order IIR filter provided in an embodiment of the present invention;

[0047] Fig.14 It is provided in the embodiment of the present invention Fig.13 A partial enlarged view of

[0048] Fig.15is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention;

[0049] Fig.16 It is a diagram showing the effect of the FIR filter pre-distortion processing provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] The inventors have found that arbitrary wave generators, as a general electronic instrument, can generate various real waveforms and excitation signals, and are widely used in modern electronic test and measurement, electronic simulation and other fields. However, due to many non-ideal characteristics in the entire hardware link from the analog circuit of the arbitrary wave generator to the load end, such as amplifier ringing, parasitic capacitance and parasitic inductance in the line, impedance mismatch, etc., the output signal of the arbitrary wave generator has different degrees of distortion when it reaches the load end, including ringing, overshoot, reflection standing wave, etc. These distortions are often unacceptable in some precision electronic test and measurement applications.

[0053] Currently, waveform pre-distortion is often used to reduce waveform distortion caused by non-ideal characteristics of hardware links. The basic principle of this waveform pre-distortion method is to first obtain the frequency domain response of the link by measurement, and then take the inverse of the frequency domain response as the response of the pre-distortion processing. The original waveform of the arbitrary waveform generator is first processed by the pre-distortion processing before being output, and then this part of the non-ideal characteristics will be offset when passing through the actual link, thereby reducing waveform distortion when reaching the load end.

[0054] In the actual implementation process, there are generally two ways to obtain the frequency response of the arbitrary wave generator hardware link. One method is direct measurement, where the arbitrary wave generator outputs single-frequency sine wave signals of different frequencies in the frequency band in sequence with a certain frequency step, and then uses an oscilloscope to collect the amplitude and phase of each frequency signal to obtain the frequency response of the hardware link in the entire frequency band. The disadvantage of this method is that a large number of tests are required to obtain more accurate results. Another method is to use the principle that the impulse response of the system is transformed into the frequency domain as the frequency response of the system. The arbitrary wave generator outputs an ideal step signal, and the oscilloscope is used to collect the step signal to obtain the step response of the system. The step response is differentially calculated to obtain the impulse response of the system, and then the impulse response is Fourier transformed to obtain the frequency response of the system. Although this method does not require a large number of tests, in order to obtain accurate frequency response results, it is necessary to perform FFT operations on waveforms with a large number of points, which requires a large amount of calculations.

[0055] After obtaining the frequency response of the system, there are generally two methods to pre-distort the original waveform data. One method is to use a higher-order digital filter to approximate the inverse frequency response of the system, and then use the filter to pre-distort the data. The other method is to perform FFT on the original waveform, then multiply it by the inverse of the FFT result of the system impulse response, and finally perform inverse FFT to obtain the pre-distorted waveform.

[0056] Although the above waveform predistortion method can theoretically handle distortion caused by any non-ideal characteristics, it has the disadvantages of large amount of calculation, inconvenience in real-time processing, insufficient resolution of the measured frequency response, which may lead to poor correction effect of long-term overshoot distortion, and sensitivity to noise in practical applications.

[0057] To this end, an embodiment of the present invention provides an arbitrary wave generator predistortion method, which can realize the correction of long-time overshoot type distortion signals, and has a simple measurement method, small calculation amount and good correction effect.

[0058] Figure 1 1 is a flow chart of an arbitrary wave generator predistortion method provided in an embodiment of the present invention. This embodiment can be applied to correct the distorted signal output by the arbitrary wave generator. Figure 1 As shown, the method includes:

[0059] S110, obtaining a time domain pulse step response signal output by an arbitrary wave generator.

[0060] Among them, the time domain pulse step response signal of the arbitrary wave generator can be collected by an oscilloscope, and compared with the traditional method of directly measuring the frequency response of the system, the measurement method is simpler.

[0061] The time domain pulse step response signal includes a distortion signal, such as a long-time overshoot type distortion signal.

[0062] Figure 2 is a schematic diagram of a distorted waveform collected by an oscilloscope provided in an embodiment of the present invention, Figure 3 It is provided in the embodiment of the present invention Figure 2 A partial enlarged view of the reference Figure 2 and Figure 3 , the pulse step response waveform collected by the oscilloscope has a larger amplitude and longer duration distortion compared to the ideal pulse step response.

[0063] S120: Establish a time domain distortion model according to the time domain pulse step response signal.

[0064] The waveform distortion is mainly caused by amplifier ringing, parasitic capacitance and inductance in the line, impedance mismatch, uneven system frequency response, etc. Among them, parasitic capacitance and inductance in the line generally cause overshoot distortion with a long duration.

[0065] Figure 4 Schematic diagram of the circuit structure of the arbitrary wave generator and the load provided in the embodiment of the present invention. Figure 4 , U s (t) is the output voltage of the arbitrary wave generator, R s is the output impedance of the arbitrary wave generator, L is the parasitic inductance of the line, C is the parasitic capacitance of the line, R is the load resistance, and y(t) is the voltage across the load.

[0066] When U s When (t) = u(t) (u(t) is a unit step function), the arbitrary wave generator outputs a step voltage. The voltage at the load end can be deduced from the response of the RLC circuit as follows:

[0067]

[0068] Among them, c 2 、c 3 、s 1 、s 2 With R s , R, L, C. From the above formula, we can see that the parasitic capacitance and parasitic inductance in the line will superimpose the distortion of multi-exponential response in the time domain step waveform.

[0069] For example, taking the first-order exponential response distortion as an example, a time domain distortion model is established based on the time domain pulse step response signal. Assume that the step response to be played by the arbitrary wave generator is:

[0070] x(t)=u(t)

[0071] The response of the load end after superimposing exponential distortion, that is, the time domain distortion model is:

[0072] y(t)=(1+Ae -t / τ )·u(t)

[0073] Where y(t) is the voltage across the load, u(t) is the step response, A is the amplitude of the distorted signal, and τ is the time constant of the distorted signal.

[0074] S130 , correcting a long-time overshoot type distortion signal in a time-domain impulse step response signal according to a time-domain distortion model to obtain a first predistortion signal.

[0075] Among them, by establishing a time domain distortion model, the long-term overshoot type distortion signal in the time domain pulse step response signal can be calibrated, thereby compensating for the long-term overshoot type distortion signal and realizing the pre-distortion processing of the arbitrary wave generator. Compared with the existing method of directly compensating the system frequency response, the calibration effect is better.

[0076] In the technical solution of this embodiment, the working principle of the arbitrary wave generator predistortion method is: Figure 1 First, the time domain pulse step response signal output by the arbitrary wave generator is obtained. Then, the corresponding time domain distortion model is established according to the time domain pulse step response signal. Finally, the long-time overshoot type distortion signal in the time domain pulse step response signal is corrected according to the time domain distortion model, thereby compensating the long-time overshoot type distortion signal, so that all the long-time overshoot distortion is compensated. Compared with the traditional method of directly compensating the system frequency response, by establishing a time domain distortion model corresponding to the time domain pulse step response signal, the correction effect of the long-time overshoot distortion is better.

[0077] The technical solution of this embodiment provides an arbitrary wave generator predistortion method, which includes: obtaining a time domain pulse step response signal output by the arbitrary wave generator; establishing a time domain distortion model according to the time domain pulse step response signal; and correcting the long-time overshoot type distortion signal in the time domain pulse step response signal according to the time domain distortion model to obtain a first predistortion signal. It can be seen that this method can achieve: obtaining the predistortion response by measuring the time domain pulse step response signal of the arbitrary wave generator, and the measurement method is simpler than the traditional direct measurement system frequency response. And by establishing a time domain distortion model, the long-time overshoot type distortion signal can be corrected by the time domain distortion model, and compared with the existing method, the correction effect is good and the calculation amount is small.

[0078] Figure 5 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention. Based on the above embodiment, optionally, refer to Figure 5 , the method comprises the following steps:

[0079] S210, obtaining a time domain pulse step response signal output by an arbitrary wave generator.

[0080] S220: Establish a time domain distortion model according to the time domain pulse step response signal.

[0081] S230 , obtaining a first-order IIR filter according to the time domain distortion model.

[0082] Among them, after the corresponding time domain distortion model is established according to the time domain pulse step response signal, a first-order IIR filter can be obtained according to the time domain distortion model, so that the long-time overshoot type distortion signal can be corrected through the first-order IIR filter later.

[0083] S240 , obtaining distortion model parameters of a first-order IIR filter according to the time-domain pulse step response signal and the time-domain distortion model.

[0084] Optionally, the distortion model parameters of the first-order IIR filter include the amplitude and time constant of the distortion signal.

[0085] S250 , correcting a long-time overshoot type distortion signal in a time-domain impulse step response signal according to the distortion model parameters of the first-order IIR filter and the first-order IIR filter.

[0086] Specifically, a first-order IIR filter is first obtained through a time domain distortion model, and then the distortion model parameters of the first-order IIR filter are obtained according to the time domain pulse step response signal and the time domain distortion model. Finally, the long-time overshoot type distortion signal in the time domain pulse step response signal is corrected according to the distortion model parameters of the first-order IIR filter and the first-order IIR filter. Thus, the long-time overshoot distortion can be corrected through a small number of IIR filters (such as the first order). Compared with the prior art, the correction effect is good, the calculation amount is small, and it is easier to implement.

[0087] In the technical solution of this embodiment, the working principle of the arbitrary wave generator predistortion method is: Figure 5First, obtain the time domain pulse step response signal output by the arbitrary wave generator. Then, establish a time domain distortion model based on the time domain pulse step response signal. Secondly, obtain a first-order IIR filter based on the time domain distortion model. Obtain the distortion model parameters of the first-order IIR filter based on the time domain pulse step response signal and the time domain distortion model. Finally, correct the long-time overshoot type distortion signal in the time domain pulse step response signal based on the distortion model parameters of the first-order IIR filter and the first-order IIR filter. It can be seen that the correction of long-time overshoot distortion can be achieved by using a small number of IIR filters (such as first order). Compared with the prior art, the correction effect is good, the calculation amount is small, and it is easier to implement. In addition, the pre-distortion response is obtained by measuring the time domain pulse step response signal of the arbitrary wave generator. Compared with the traditional direct measurement system frequency response, the measurement method is simpler.

[0088] Figure 6 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention. Based on the above embodiment, optionally, refer to Figure 6 , the method comprises the following steps:

[0089] S310, obtaining a time domain pulse step response signal output by an arbitrary wave generator.

[0090] S320: Establish a time domain distortion model according to the time domain pulse step response signal.

[0091] S330, performing Laplace transform, predistortion transform and bilinear transform on the time domain distortion model in sequence to obtain a first-order IIR filter.

[0092] Among them, after the time domain distortion model is established according to the time domain pulse step response signal, the complex frequency domain response causing the distortion can be obtained by Laplace transforming the time domain distortion model:

[0093]

[0094] Then, a predistortion transformation is performed on the complex frequency domain response, and the predistortion frequency response that can offset the line frequency response causing the distortion is:

[0095]

[0096] Finally, by performing a bilinear transformation on the predistortion frequency response, the z-transform of the IIR digital filter that approximately implements the predistortion frequency response can be obtained as:

[0097]

[0098] in,

[0099]

[0100] in,

[0101]

[0102] in,

[0103]

[0104] in,

[0105] λ=2τ(A+1)+T s

[0106] Among them, T s is the sampling time, A is the amplitude of the distortion signal, and τ is the time constant of the distortion signal.

[0107] It can be seen that the first-order exponential response distortion can be corrected by using a first-order IIR filter. Using a small number of filters can reduce the amount of calculation and improve the correction effect. It is easy to implement through the time domain distortion model and the first-order IIR filter.

[0108] S340 , fitting the time domain pulse step response signal and the time domain distortion model to obtain distortion model parameters of the first-order IIR filter.

[0109] The method of fitting the time domain pulse step response signal and the time domain distortion model may adopt a fitting function, such as a curve_fit function.

[0110] Among them, fitting the time domain pulse step response signal and the time domain distortion model can reduce the influence of measurement noise.

[0111] Figure 7 Schematic diagram of fitting a time domain pulse step response signal and a time domain distortion model provided in an embodiment of the present invention. Figure 7 , curve S1 is the time domain pulse step response signal, curve S2 is the time domain distortion model, the fitting reference of the time domain pulse step response signal and the time domain distortion model Figure 7 .

[0112] S350 , inputting the distortion model parameters of the first-order IIR filter into the first-order IIR filter to compensate for the long-time overshoot type distortion signal in the time-domain impulse step response signal.

[0113] Among them, the coefficients of the first-order IIR filter can be obtained by inputting the distortion model parameters of the first-order IIR filter into the first-order IIR filter, so that the first-order IIR filter can be used to perform pre-distortion processing on the time domain pulse step response signal, and the long-term overshoot distortion signal in the time domain pulse step response signal can be corrected, thereby compensating for the distortion response of the actual link. Figure 8is a schematic diagram of a signal waveform after being pre-distorted by a first-order IIR filter provided in an embodiment of the present invention, Fig. 9 It is provided in the embodiment of the present invention Figure 8 A partial enlarged view of the Figure 8 and Fig. 9 It can be seen that after compensation by the first-order IIR filter, the fitted distorted response is compensated.

[0114] It should be noted that if multiple exponential response distortions are superimposed in an actual line, multiple first-order IIR filters can be used to perform multiple corrections. Fig.10 is a schematic diagram of a waveform after being pre-distorted by multiple IIR filters provided in an embodiment of the present invention, Fig.11 It is provided in the embodiment of the present invention Fig.10 When the distorted waveform has multiple long-term overshoot distortions, the above process can be repeated many times to obtain multiple IIR filters, and the overshoot distortion can be compensated by multiple IIR filters. The waveform after pre-distortion processing by multiple IIR filters is as follows: Fig.10 and Fig.11 .

[0115] In the technical solution of this embodiment, the working principle of the arbitrary wave generator predistortion method is: Figure 6 First, the time domain pulse step response signal output by the arbitrary wave generator is obtained. Then, a time domain distortion model is established according to the time domain pulse step response signal. Secondly, the time domain distortion model is subjected to Laplace transform, pre-distortion transform and bilinear transform in sequence to obtain a first-order IIR filter. The time domain pulse step response signal and the time domain distortion model are fitted to obtain the distortion model parameters of the first-order IIR filter. Finally, the distortion model parameters of the first-order IIR filter are input into the first-order IIR filter to compensate for the long-time overshoot type distortion signal in the time domain pulse step response signal. It can be seen that the correction of long-time overshoot distortion can be achieved by using a small number of IIR filters (such as the first order). Compared with the prior art, the correction effect is good, the calculation amount is small, and it is easier to implement. Moreover, the pre-distortion response is obtained by measuring the time domain pulse step response signal of the arbitrary wave generator, and the measurement method is simpler than the traditional direct measurement system frequency response.

[0116] Fig.12 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention. Based on the above embodiment, optionally, the method includes the following steps:

[0117] S410, obtaining a time domain pulse step response signal output by an arbitrary wave generator.

[0118] S420: Establish a time domain distortion model according to the time domain pulse step response signal.

[0119] S430 , correcting a long-time overshoot type distortion signal in the time-domain impulse step response signal according to a time-domain distortion model to obtain a first predistortion signal.

[0120] S440: Perform a differential operation on the first predistortion signal to obtain an impulse response.

[0121] Among them, after the long-term overshoot distortion signal is processed through the above steps, the step waveform, ie, the first pre-distortion signal, still has some residual distortion of a shorter duration. Fig.13 is a schematic diagram of a distorted signal with a relatively short residual time after being pre-distorted by a first-order IIR filter provided in an embodiment of the present invention, Fig.14 It is provided in the embodiment of the present invention Fig.13 A partial enlarged view of the distorted signal. The distorted signal with a shorter residual time after the first-order IIR filter pre-distortion is as follows: Fig.13 and Fig.14 As shown, these shorter duration distortions are generally caused by amplifier ringing, impedance mismatch, etc.

[0122] Specifically, the impulse response h(n) may be obtained by performing a differential operation on the first predistorted signal predistorted by the first-order IIR filter.

[0123] S450: Obtain a predistorted impulse response according to the impulse response and the unit impulse function.

[0124] For example, assuming that the predistorted impulse response is h inv (n), then

[0125] h(n)*h inv (n) = δ(n)

[0126] Among them, δ(n) is the unit impulse function. Therefore, we only need to obtain the predistorted impulse response h inv (n) The predistortion response can be obtained by satisfying the above formula, that is, the short-term distortion signal in the first predistortion signal is corrected.

[0127] S460: Perform predistortion processing on the first predistortion signal according to the predistortion impulse response to obtain a second predistortion signal.

[0128] Optionally, before performing the differential operation on the first predistortion signal, the method further includes: performing normalization processing on the first predistortion signal.

[0129] In the technical solution of this embodiment, the working principle of the arbitrary wave generator predistortion method is: Fig.12First, obtain the time domain pulse step response signal output by the arbitrary wave generator. Then, establish a time domain distortion model according to the time domain pulse step response signal. Secondly, correct the long-time overshoot type distortion signal in the time domain pulse step response signal according to the time domain distortion model to obtain a first pre-distortion signal. Perform a differential operation on the first pre-distortion signal to obtain an impulse response. The pre-distorted impulse response is obtained according to the impulse response and the unit impulse function. Finally, the first pre-distortion signal is pre-distorted according to the pre-distorted impulse response to obtain a second pre-distortion signal. It can be seen that the correction of long-time overshoot distortion can be achieved by using a small number of IIR filters (such as first order). Compared with the prior art, the correction effect is good, the calculation amount is small, and it is easier to implement. After the time-domain pulse step response signal is pre-distorted by the first-order IIR filter, the pre-distorted impulse response is obtained by differential operation of the signal (i.e., the first distorted signal) after the first-order IIR filter pre-distortion processing, and the signal after the first-order IIR filter pre-distortion processing is pre-distorted by the pre-distorted impulse response, so that the residual distorted signal with a short duration can be processed, thereby improving the reliability of the arbitrary wave generator distorted signal processing and improving the accuracy of the distorted signal correction. In addition, the pre-distortion response is obtained by measuring the time-domain pulse step response signal of the arbitrary wave generator, and the measurement method is simpler than the traditional direct measurement system frequency response.

[0130] Fig.15 is a flow chart of another arbitrary wave generator predistortion method provided in an embodiment of the present invention. Based on the above embodiment, optionally, refer to Fig.15 , the method comprises the following steps:

[0131] S510, obtaining a time domain pulse step response signal output by an arbitrary wave generator.

[0132] S520: Establish a time domain distortion model according to the time domain pulse step response signal.

[0133] S530 , correcting a long-time overshoot type distortion signal in a time-domain impulse step response signal according to a time-domain distortion model to obtain a first predistortion signal.

[0134] S540: Perform a differential operation on the first predistortion signal to obtain an impulse response.

[0135] S550 , obtaining a predistorted impulse response using an L2 regularization method according to the impulse response and the unit impulse function.

[0136] S560: Use the predistorted impulse response as a coefficient of an FIR filter, and perform predistortion processing on the first predistortion signal according to the FIR filter to obtain a second predistortion signal.

[0137] In practical applications, the measured impulse response h(n) is often superimposed with noise in addition to the useful signal, which will result in the final obtained predistorted impulse response h inv (n) There is a large error. In order to reduce the influence of noise, the embodiment of the present invention adopts the L2 regularization method to solve the predistortion impulse response h inv (n), as follows:

[0138]

[0139] in, is the regularization term, and α is the regularization coefficient.

[0140] Fig.16 : is the effect diagram after the FIR filter pre-distortion processing provided in the embodiment of the present invention. The obtained pre-distortion impulse response is used as the coefficient of the FIR digital filter, and the FIR digital filter is used to implement the pre-distortion processing of the original waveform. The waveform after FIR pre-distortion processing is as follows Fig.16 As shown, curve L1 is the waveform before FIR filter processing, and curve L2 is the waveform after FIR filter processing. Fig.16 It can be seen that the distorted signal is compensated and the waveform after pre-distortion processing is close to the ideal waveform.

[0141] In the technical solution of this embodiment, the working principle of the arbitrary wave generator predistortion method is: Fig.15First, obtain the time domain pulse step response signal output by the arbitrary wave generator. Then, establish a time domain distortion model according to the time domain pulse step response signal. Secondly, correct the long-time overshoot type distortion signal in the time domain pulse step response signal according to the time domain distortion model to obtain a first pre-distortion signal. Perform a differential operation on the first pre-distortion signal to obtain an impulse response. Use the L2 regularization method according to the impulse response and the unit impulse function to obtain the pre-distorted impulse response. Use the pre-distorted impulse response as the coefficient of the FIR filter, and pre-distort the first pre-distortion signal according to the FIR filter to obtain a second pre-distortion signal. It can be seen that the correction of long-time overshoot distortion can be achieved by using a small number of IIR filters (such as first order). Compared with the prior art, the correction effect is good, the calculation amount is small, and it is easier to implement. And after the time-domain pulse step response signal is pre-distorted by the first-order IIR filter, the pre-distorted impulse response is obtained by differential operation of the signal (i.e., the first distorted signal) after the first-order IIR filter pre-distortion processing, and the signal after the first-order IIR filter pre-distortion processing is pre-distorted by the pre-distorted impulse response, so that the residual distorted signal with a short duration can be processed, thereby improving the reliability of the arbitrary wave generator distortion signal processing and improving the accuracy of the distortion signal correction. In addition, the L2 regularization method is used when solving the pre-distortion impulse response to reduce the influence of measurement noise. It can be seen that the measurement method of obtaining the pre-distortion response by measuring the time-domain pulse step response signal of the arbitrary wave generator is simpler than the traditional direct measurement system frequency response. By establishing a time-domain distortion model to correct the long-term overshoot distortion signal, the correction effect is better than the prior art method of directly compensating the system frequency response. And the pre-distortion processing of the time-domain pulse step response signal can be realized by a small number of IIR filters and FIR filters, and the distortion signal of the long-time overshoot type, the distortion signal of the short duration and the noise signal can be corrected. Compared with the FFT pre-distortion processing method used in the prior art, the amount of calculation is smaller and it is convenient for the implementation of real-time processors such as FPGA. In addition, the influence of measurement noise can be reduced by fitting the time-domain pulse step response signal and the time-domain distortion model, and solving the pre-distortion impulse response by the L2 regularization method.

[0142] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0143] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A predistortion method for an arbitrary wave generator, characterized in that: include: Acquire a time-domain pulse step response signal output by the arbitrary wave generator; Establishing a time domain distortion model according to the time domain pulse step response signal; A long-time overshoot type distortion signal in the time-domain impulse step response signal is corrected according to the time-domain distortion model to obtain a first predistortion signal.

2. The arbitrary wave generator predistortion method according to claim 1, characterized in that: The correcting the long-time overshoot type distortion signal in the time-domain pulse step response signal according to the time-domain distortion model comprises: Obtaining a first-order IIR filter according to the time domain distortion model; Obtaining distortion model parameters of a first-order IIR filter according to the time-domain impulse step response signal and the time-domain distortion model; A long-time overshoot type distortion signal in the time-domain impulse step response signal is corrected according to the distortion model parameters of the first-order IIR filter and the first-order IIR filter.

3. The arbitrary wave generator predistortion method according to claim 2, characterized in that: The obtaining of a first-order IIR filter according to the time domain distortion model comprises: The time domain distortion model is subjected to Laplace transformation, predistortion transformation and bilinear transformation in sequence to obtain a first-order IIR filter.

4. The arbitrary wave generator predistortion method according to claim 2, characterized in that: The step of obtaining the distortion model parameters of the first-order IIR filter according to the time-domain impulse step response signal and the time-domain distortion model comprises: The time domain impulse step response signal and the time domain distortion model are fitted to obtain distortion model parameters of a first-order IIR filter.

5. The arbitrary wave generator predistortion method according to claim 4, characterized in that: The distortion model parameters of the first-order IIR filter include the amplitude and time constant of the distortion signal.

6. The arbitrary wave generator predistortion method according to claim 2, characterized in that: The method of correcting the long-time overshoot type distortion signal in the time domain pulse step response signal according to the distortion model parameters of the first-order IIR filter and the first-order IIR filter comprises: The distortion model parameters of the first-order IIR filter are input into the first-order IIR filter to compensate for the long-term overshoot type distortion signal in the time-domain impulse step response signal.

7. The arbitrary wave generator predistortion method according to claim 1, characterized in that: The time domain distortion model is: y(t)=(1+Ae -t / τ )·u(t) Where y(t) is the voltage across the load, u(t) is the step response, A is the amplitude of the distorted signal, and τ is the time constant of the distorted signal.

8. The arbitrary wave generator predistortion method according to claim 1, characterized in that: After correcting the long-time overshoot type distortion signal in the time-domain impulse step response signal according to the time-domain distortion model to obtain the first predistortion signal, the method further includes: performing a differential operation on the first predistortion signal to obtain an impulse response; A predistorted impulse response is obtained according to the impulse response and the unit impulse function; The first predistortion signal is predistorted according to the predistortion impulse response to obtain a second predistortion signal.

9. The arbitrary wave generator predistortion method according to claim 8, characterized in that: Before performing a differential operation on the first predistortion signal, the method further includes: Normalization processing is performed on the first predistortion signal.

10. The arbitrary wave generator predistortion method according to claim 8, characterized in that: The obtaining of the predistorted impulse response according to the impulse response and the unit impulse function comprises: obtaining the predistorted impulse response according to the impulse response and the unit impulse function using an L2 regularization method; The predistortion processing is performed on the first predistortion signal according to the predistortion impulse response to obtain the second predistortion signal, including: using the predistortion impulse response as a coefficient of an FIR filter, and predistortion processing is performed on the first predistortion signal according to the FIR filter to obtain the second predistortion signal.

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