Broadband power amplifier model and power amplifier modeling and analyzing method and system

Abstract

The invention discloses a broadband power amplifier model and a power amplifier modeling and analyzing method and system. Comprising the following steps: firstly, introducing a memory effect item and a correction factor into a memory-free power amplifier model supporting narrowband communication, and constructing a broadband power amplifier initial model; then, estimating a parameter expression of the constructed broadband power amplifier initial model, and substituting amplitude characteristic actual measurement data and phase characteristic actual measurement data, obtained through actual measurement, of different frequency points into the parameter expression to obtain power amplifier model parameters corresponding to the frequency points; and finally, according to the power amplifier model parameter corresponding to each frequency point, power amplifier model parameters of other frequency points with unknown characteristic data are calculated, and a broadband power amplifier model corresponding to the whole frequency domain is constructed. Compared with a traditional memory-free power amplifier model, due to the fact that the memory effect item and the correction factor are introduced, the established broadband power amplifier model can be suitable for describing the nonlinear characteristic of a traveling wave tube power amplifier and can also describe the memory effect caused by a broadband signal to the power amplifier.

Description

Technical Field

[0001] The present invention relates to the technical field of improving amplifiers for reducing nonlinear distortion, and in particular to a broadband power amplifier model and a power amplifier modeling, analysis method and system. Background Art

[0002] In wireless communication links, the RF link has always been an important factor restricting the performance of the communication system. RF devices such as power amplifiers are important factors affecting signal distortion and are often difficult to accurately simulate, model, test and evaluate.

[0003] Generally speaking, when the input power is small, the power amplifier has good linearity. In practical applications, in order to improve the efficiency of the power amplifier, the power amplifier needs to work in a region close to saturation, but at this time the power amplifier has strong nonlinearity, causing in-band distortion and out-of-band distortion of the transmitted signal. In-band distortion is mainly manifested as amplitude-amplitude (AM-AM) / amplitude-phase (AM-PM) modulation effects, which lead to signal amplitude and phase distortion, causing the constellation diagram to diffuse and deflect, and the bit error rate to deteriorate. Out-of-band distortion will cause signal spectrum proliferation, and a large amount of intermodulation distortion and harmonic components will cause problems such as adjacent channel interference and excessive out-of-band transmission power.

[0004] In the actual application of power amplifiers, the memory effect of power amplifiers is also an important factor affecting the performance of power amplifiers. The distortion components generated by the nonlinear characteristics of power amplifiers are not constant. For example, the amplitude and phase of third-order or fifth-order intermodulation will change with the input signal amplitude and bandwidth. This phenomenon that the distortion components depend on the input signal amplitude and bandwidth is usually called the memory effect of the power amplifier.

[0005] When analyzing a system with a load power amplifier, it is important to establish a model of the power amplifier. Currently, most of the literature focuses on the linearization of memoryless power amplifiers. For example, the Saleh model is a classic memoryless nonlinear traveling wave tube amplifier model. The Saleh model is widely used and is generally used to describe the nonlinear characteristics of traveling wave tube amplifiers. It has the advantages of simple form and convenient calculation, but the model is only suitable for describing the nonlinear characteristics of traveling wave tube amplifiers and does not have the ability to describe the memory effect of the amplifier. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes a broadband power amplifier model and a power amplifier modeling, analysis method and system. The established broadband power amplifier model is suitable for describing the nonlinear characteristics of the power amplifier and the memory effect caused by the broadband signal on the power amplifier. The specific technical solution is as follows:

[0007] In a first aspect, a power amplifier modeling method is provided. In a first implementable manner of the first aspect, the method includes:

[0008] Introducing memory effect terms and correction factors into the memoryless power amplifier model supporting narrowband communication, constructing the initial model of broadband power amplifier;

[0009] Estimate the parameter expression of the broadband power amplifier initial model, and substitute the corresponding amplitude characteristic measured data and phase characteristic measured data to determine the power amplifier model parameters corresponding to each frequency point;

[0010] The power amplifier model parameters corresponding to all frequency points between adjacent frequency points are determined according to the corresponding power amplifier model parameters, and the entire broadband power amplifier model is constructed.

[0011] In combination with the first implementable manner of the first aspect, in a second implementable manner of the first aspect, the memoryless power amplifier model is a Saleh model.

[0012] In combination with the second implementable manner of the first aspect, in a third implementable manner of the first aspect, the AM-AM characteristic in the broadband power amplifier initial model is specifically:

[0013]

[0014] Among them, A[r(n)] is the amplitude of the output signal, r(n) is the amplitude of the input signal, α A , β A is the AM-AM parameter, μ A is the amplitude correction factor.

[0015] In combination with the second implementable manner of the first aspect, in a fourth implementable manner of the first aspect, the AM-PM characteristic in the broadband power amplifier initial model is specifically:

[0016]

[0017] Where, Φ[r(n)] is the phase of the output signal, α Φ , β Φ is the AM-PM parameter, μ Φ is the phase correction factor.

[0018] In combination with the first implementable manner of the first aspect, in a fifth implementable manner of the first aspect, estimating a parameter expression of the broadband power amplifier initial model includes:

[0019] The least square method is used to determine the parameter expression of the broadband power amplifier initial model.

[0020] In combination with the first implementable manner of the first aspect, in a sixth implementable manner of the first aspect, determining the power amplifier model parameters corresponding to all frequency points between adjacent frequency points includes:

[0021] Based on the power amplifier model parameters corresponding to the adjacent frequency points, the power amplifier model parameters corresponding to all the frequency points between the adjacent frequency points are determined by using the cubic interpolation method or the Lagrange interpolation method.

[0022] In a second aspect, a broadband power amplifier model is provided, including: a memoryless power amplifier model supporting narrowband communication, a memory effect term and a correction factor.

[0023] In a third aspect, a power amplifier analysis method is provided, comprising:

[0024] Adopting the power amplifier modeling method as described in any one of the first to sixth possible implementations of the first aspect to establish a broadband power amplifier model corresponding to the power amplifier;

[0025] According to the amplitude measurement value of the power amplifier input signal, the amplitude value and phase value of the power amplifier output signal are predicted by the broadband power amplifier model.

[0026] In a fourth aspect, a power amplifier modeling system is provided, comprising:

[0027] A construction module configured to introduce a memory effect term and a correction factor into a memoryless power amplifier model supporting narrowband communication, so as to construct an initial model of a broadband power amplifier;

[0028] A calculation module is configured to estimate the parameter expression of the broadband power amplifier initial model, and determine the power amplifier model parameters corresponding to different frequency points in combination with the corresponding measured amplitude characteristic data and phase characteristic data;

[0029] The modeling module is configured to determine the power amplifier model parameters corresponding to all frequency points between adjacent frequency points according to the corresponding power amplifier model parameters, and construct the entire broadband power amplifier model.

[0030] In a fifth aspect, a power amplifier analysis system is provided, comprising:

[0031] A model building module, configured to adopt the power amplifier modeling method described in any one of the first to sixth implementations of the first aspect to establish a corresponding broadband power amplifier model;

[0032] The signal analysis module is configured to predict the predicted values ​​of the AM-AM characteristics and the AM-PM characteristics of the output signal of the power amplifier through the broadband power amplifier model according to the amplitude measurement value and frequency of the input signal of the power amplifier.

[0033] Beneficial effect: By adopting the broadband power amplifier model and power amplifier modeling, analysis method and system of the present invention, a memory effect term and a corresponding correction factor are introduced on the basis of the memoryless power amplifier model, so that the established broadband power amplifier model can be suitable for describing the nonlinear characteristics of the traveling wave tube power amplifier and the memory effect caused by the broadband signal on the power amplifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0035] Figure 1 A flowchart of a power amplifier modeling method provided by an embodiment of the present invention;

[0036] Figure 2 A flowchart of a power amplifier analysis method provided by an embodiment of the present invention;

[0037] Figure 3 A system block diagram of a power amplifier modeling system provided by an embodiment of the present invention;

[0038] Figure 4 A system block diagram of a power amplifier analysis system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0040] like Figure 1 A flowchart of a power amplifier modeling method is shown, the modeling method comprising:

[0041] Step 1: Introduce memory effect terms and correction factors into the memoryless power amplifier model supporting narrowband communication to construct an initial model of a broadband power amplifier;

[0042] Step 2, estimating the parameter expression of the broadband power amplifier initial model, and substituting the corresponding amplitude characteristic measured data and phase characteristic measured data into it to determine the power amplifier model parameters corresponding to each frequency point;

[0043] Step 3: Determine the power amplifier model parameters corresponding to all frequency points between adjacent frequency points according to the corresponding power amplifier model parameters, and construct the entire broadband power amplifier model.

[0044] Specifically, first, a memory effect term is introduced into the memoryless power amplifier model supporting narrowband communication. At the same time, in order to accurately describe the distortion of the wideband signal passing through the traveling wave tube power amplifier, a correction factor is also introduced, so that the constructed broadband power amplifier initial model is more suitable for power amplifiers with larger bandwidth and more frequency bands. Then, the parameter expression of the constructed broadband power amplifier initial model is estimated by the existing mathematical optimization method, and the measured data of the amplitude characteristics and the measured data of the phase characteristics at different frequency points obtained by actual measurement are substituted into the parameter expression to obtain the power amplifier model parameters corresponding to each frequency point, and the corresponding power amplifier model parameters are substituted into the broadband power amplifier initial model to obtain the broadband power amplifier model corresponding to different frequency points.

[0045] Since the measured data of the power amplifier characteristics are discrete, the power amplifier model parameters corresponding to the frequency points of other unknown characteristic data can be deduced based on the power amplifier model parameters corresponding to the frequency points of each known characteristic measured data, thereby constructing a broadband power amplifier model corresponding to the entire frequency domain, effectively improving the accuracy of modeling. Compared with the traditional memoryless power amplifier model, due to the introduction of memory effect terms and correction factors, the established broadband power amplifier model can be adapted to describe the nonlinear characteristics of the traveling wave tube power amplifier, and can also describe the memory effect caused by broadband signals on the power amplifier.

[0046] In this embodiment, the memoryless power amplifier model is optionally a Saleh model. Specifically, the Saleh model is a relatively classic and widely used power amplifier model, and the expression is relatively simple. Therefore, this embodiment selects the Saleh model as the basis for constructing a broadband power amplifier model.

[0047] In this embodiment, optionally, the AM-AM characteristics in the broadband power amplifier initial model are specifically:

[0048]

[0049] Among them, A[r(n)] is the amplitude of the output signal, r(n) is the amplitude of the input signal, α A , β A is the AM-AM parameter, μ A is the amplitude correction factor.

[0050] In this embodiment, optionally, the AM-PM characteristic in the broadband power amplifier initial model is specifically:

[0051]

[0052] Where, Φ[r(n)] is the phase of the output signal, α Φ , β Φ is the AM-PM parameter, μ Φ is the phase correction factor.

[0053] In this embodiment, optionally, estimating a parameter expression of the broadband power amplifier initial model includes:

[0054] The least square method is used to determine the parameter expression of the broadband power amplifier initial model. Since the least square method is the simplest and has a small amount of calculation, the least square method is used to determine the parameter expression of the broadband power amplifier initial model, which can effectively reduce the complexity of modeling and improve modeling efficiency.

[0055] Specifically, Then the AM-AM characteristic and AM-PM characteristic can be rewritten as:

[0056]

[0057] Among them, A(n) = A[r(n)] and Φ(n) = Φ[r(n)] are the measured values ​​of the amplitude and phase of the output signal. The parameters to be calculated are written in the form of vectors:

[0058]

[0059] Using the classical least squares method, the predicted value of the model output is The sum of the squares of the distances from the measured values ​​A(n) and Φ(n) is minimized, and we get:

[0060]

[0061] in:

[0062]

[0063] W A =[R(0),R(1),…,R(N-1)] T ;

[0064] W Φ =[R 2 (0),R 2 (1),…,R 2 (N-1)] T ;

[0065] Calculate and After that, the power amplifier model parameters corresponding to each frequency point can be obtained:

[0066]

[0067] By bringing each power amplifier model parameter into the broadband power amplifier initial model, the broadband power amplifier model corresponding to each frequency point can be obtained.

[0068] In this embodiment, optionally, determining the power amplifier model parameters corresponding to all frequency points between adjacent frequency points includes:

[0069] Based on the power amplifier model parameters corresponding to the adjacent frequency points, the power amplifier model parameters corresponding to all the frequency points between the adjacent frequency points are determined by using the cubic interpolation method or the Lagrange interpolation method.

[0070] Specifically, since the given power amplifier characteristic data is discrete in the frequency of the input signal, the power amplifier characteristics of the ungiven frequency part between adjacent input frequencies can be obtained by performing Lagrange interpolation or cubic interpolation on the power amplifier characteristic data of the adjacent input frequencies.

[0071] Taking the input signal frequencies of 15.4 GHz, 15.5 GHz and 15.6 GHz as examples, assuming that the power amplifier model parameters corresponding to the AM-AM characteristics of these three frequencies are α A15.4 , β A15.4 , μ A15.4 , γ A15.4 ; α A15.5 , β A15.5 , μ A15.5 , γ A15.5 and α A15.6 , β A15.6 , μ A15.6 , γ A15.6 .

[0072] Based on the calculated power amplifier model parameters, the power amplifier model parameters corresponding to each frequency point between 15.4GHz and 15.6GHz can be calculated, specifically:

[0073]

[0074]

[0075] Where f is the signal frequency, γ A15.6 , γ A15.5 , γ A15.4 They are the amplitudes of the input signals corresponding to 15.6GHz, 15.5GHz and 15.4GHz respectively. Similarly, the cubic interpolation method can be used to calculate the power amplifier model parameters corresponding to the AM-PM characteristics of all frequencies between adjacent frequency points. Substituting the calculated power amplifier model parameters into the models corresponding to the AM-AM characteristics and AM-PM characteristics, the entire broadband power amplifier model can be constructed.

[0076] A broadband power amplifier model includes: a memoryless power amplifier model supporting narrowband communication, a memory effect term and a correction factor. Compared with the traditional memoryless power amplifier model, the introduction of the memory effect term and the correction factor enables the broadband power amplifier model to be suitable for describing the nonlinear characteristics of the traveling wave tube power amplifier and the memory effect caused by the broadband signal on the power amplifier.

[0077] like Figure 2 A flowchart of a power amplifier analysis method is shown, the analysis method comprising:

[0078] Step S1, using the above-mentioned power amplifier modeling method to establish a broadband power amplifier model corresponding to the power amplifier;

[0079] Step S2: predicting the predicted values ​​of the AM-AM characteristic and the AM-PM characteristic of the power amplifier output signal by using the broadband power amplifier model according to the amplitude measurement value of the power amplifier input signal.

[0080] Specifically, first, the above-mentioned power amplifier modeling method can be used to construct a broadband power amplifier model that is suitable for describing the nonlinear characteristics of the traveling wave tube power amplifier and the memory effect caused by the broadband signal on the power amplifier. Then, the corresponding broadband power amplifier model is determined according to the signal frequency of the power amplifier input signal, and the amplitude measurement value of the input signal is input into the broadband power amplifier model. The predicted values ​​of the AM-AM characteristics and AM-PM characteristics of the power amplifier output signal can be obtained through the broadband power amplifier model.

[0081] like Figure 3 The system block diagram of the power amplifier modeling system shown in FIG. 1 includes:

[0082] A construction module configured to introduce a memory effect term and a correction factor into a memoryless power amplifier model supporting narrowband communication, so as to construct an initial model of a broadband power amplifier;

[0083] A calculation module is configured to estimate the parameter expression of the broadband power amplifier initial model, and determine the power amplifier model parameters corresponding to different frequency points in combination with the corresponding measured amplitude characteristic data and phase characteristic data;

[0084] The modeling module is configured to determine the power amplifier model parameters corresponding to all frequency points between adjacent frequency points according to the corresponding power amplifier model parameters, and construct the entire broadband power amplifier model.

[0085] Specifically, the modeling system is composed of a construction module, a calculation module and a modeling module. Among them, the construction module can introduce a memory effect term into the memoryless power amplifier model supporting narrowband communication, and at the same time introduce a correction factor to construct a corresponding broadband power amplifier initial model. The calculation module can use the existing mathematical optimization method to estimate the parameter expression of the constructed broadband power amplifier initial model, and substitute the measured amplitude characteristic data and phase characteristic measured data of different frequency points obtained by actual measurement into the parameter expression, so as to obtain the power amplifier model parameters corresponding to each frequency point, and substitute the corresponding power amplifier model parameters into the broadband power amplifier initial model to obtain the broadband power amplifier model corresponding to different frequency points. The modeling module can infer the power amplifier model parameters corresponding to the frequency points of other unknown characteristic data according to the power amplifier model parameters corresponding to the frequency points of each known characteristic measured data, so as to construct a broadband power amplifier model corresponding to the entire frequency domain. Compared with the traditional memoryless power amplifier model, due to the introduction of memory effect terms and correction factors, the established broadband power amplifier model can be adapted to describe the nonlinear characteristics of the traveling wave tube power amplifier, and can also describe the memory effect caused by the broadband signal on the power amplifier.

[0086] like Figure 4 The system block diagram of the power amplifier analysis system shown in FIG. 1 includes:

[0087] A model building module is configured to adopt the above-mentioned power amplifier modeling method to establish a corresponding broadband power amplifier model;

[0088] The signal analysis module is configured to predict the predicted values ​​of the AM-AM characteristics and the AM-PM characteristics of the power amplifier output signal through the broadband power amplifier model according to the amplitude measurement value and frequency of the power amplifier input signal.

[0089] Specifically, the analysis system is composed of a model building module and a signal analysis module. The model building module can adopt the above-mentioned power amplifier modeling method to build a broadband power amplifier model that is suitable for describing the nonlinear characteristics of the traveling wave tube power amplifier and the memory effect caused by the broadband signal on the power amplifier. The signal analysis module can determine the corresponding broadband power amplifier model according to the signal frequency of the power amplifier input signal, and input the amplitude measurement value of the input signal into the broadband power amplifier model. The predicted values ​​of the AM-AM characteristics and AM-PM characteristics of the power amplifier output signal can be obtained through the broadband power amplifier model.

[0090] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A power amplifier modeling method, characterized in that: include: Introducing memory effect terms and correction factors into the memoryless power amplifier model supporting narrowband communication, constructing the initial model of broadband power amplifier; Estimate the parameter expression of the broadband power amplifier initial model, and substitute the corresponding amplitude characteristic measured data and phase characteristic measured data to determine the power amplifier model parameters corresponding to each frequency point; The power amplifier model parameters corresponding to all frequency points between adjacent frequency points are determined according to the corresponding power amplifier model parameters, and the entire broadband power amplifier model is constructed.

2. The power amplifier modeling method according to claim 1, characterized in that: The memoryless power amplifier model is a Saleh model.

3. The power amplifier modeling method according to claim 2, characterized in that: The AM-AM characteristics in the broadband power amplifier initial model are specifically: Among them, A[r(n)] is the amplitude of the output signal, r(n) is the amplitude of the input signal, α A , β A is the AM-AM parameter, μ A is the amplitude correction factor.

4. The power amplifier modeling method according to claim 2, characterized in that: The AM-PM characteristics in the broadband power amplifier initial model are specifically: Where, Φ[r(n)] is the phase of the output signal, α Φ , β Φ is the AM-PM parameter, μ Φ is the phase correction factor.

5. The power amplifier modeling method according to claim 1, characterized in that: Estimating the parameter expression of the broadband power amplifier initial model includes: The least square method is used to determine the parameter expression of the broadband power amplifier initial model.

6. The power amplifier modeling method according to claim 1, characterized in that: Determine the power amplifier model parameters corresponding to all frequency points between adjacent frequency points, including: Based on the power amplifier model parameters corresponding to the adjacent frequency points, the power amplifier model parameters corresponding to all the frequency points between the adjacent frequency points are determined by using the cubic interpolation method or the Lagrange interpolation method.

7. A broadband power amplifier model, characterized in that: include: Memoryless power amplifier model, memory effect terms and correction factors supporting narrowband communications.

8. A power amplifier analysis method, characterized in that: include: Using the power amplifier modeling method as described in any one of claims 1 to 6, a broadband power amplifier model corresponding to the power amplifier is established; According to the amplitude measurement value of the power amplifier input signal, the predicted values ​​of the AM-AM characteristic and the AM-PM characteristic of the power amplifier output signal are predicted by the broadband power amplifier model.

9. A power amplifier modeling system, characterized in that: include: A construction module configured to introduce a memory effect term and a correction factor into a memoryless power amplifier model supporting narrowband communication, so as to construct an initial model of a broadband power amplifier; A calculation module is configured to estimate the parameter expression of the broadband power amplifier initial model, and determine the power amplifier model parameters corresponding to different frequency points in combination with the corresponding measured amplitude characteristic data and phase characteristic data; The modeling module is configured to determine the power amplifier model parameters corresponding to all frequency points between adjacent frequency points according to the corresponding power amplifier model parameters, and construct the entire broadband power amplifier model.

10. A power amplifier analysis system, characterized in that: include: A model building module, configured to use the power amplifier modeling method according to any one of claims 1 to 6 to establish a corresponding broadband power amplifier model; The signal analysis module is configured to predict the predicted values ​​of the AM-AM characteristics and the AM-PM characteristics of the output signal of the power amplifier through the broadband power amplifier model according to the amplitude measurement value and frequency of the input signal of the power amplifier.

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