A method for overall optimization design of a Doherty power amplifier output network

Abstract

The application belongs to the technical field of wireless communication, and provides a Doherty power amplifier output network overall optimization design method, adopts a curved broken line type irregular circuit structure, utilizes a multi-objective evolution algorithm to call HFSS simulation software to perform electromagnetic simulation on the irregular circuit, and outputs the simulation result to ADS simulation software through an application program, performs joint simulation and optimization on the 3-port output network of the Doherty power amplifier; the application fully utilizes the solving capability of the multi-objective evolution algorithm and the design freedom of the irregular circuit structure, effectively simplifies the design steps, and improves the working bandwidth and efficiency of the Doherty power amplifier.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and in particular relates to a method for overall optimization design of Doherty power amplifier output network. Background Technology

[0002] With the development of computer and intelligent computing technologies, optimization algorithms and their applications in the field of electronic information have become a research hotspot and development trend. Among them, multi-objective evolutionary algorithms, with their strong modeling capabilities and ease of solving complex engineering problems, have been widely applied in practical engineering design. On the other hand, Doherty power amplifiers (Doherty power amplifiers for short) are high-efficiency power amplifiers widely used in wireless communication network systems, and their performance has a significant impact on the data transmission rate and energy efficiency of the entire system. The output network of a Doherty power amplifier is a core component determining its operating efficiency and output power; it is essentially a 3-port network. Therefore, researching how to apply multi-objective optimization algorithms to the output network optimization design of Doherty power amplifiers has significant practical and engineering value.

[0003] like Figure 1 As shown, in the design of traditional Doherty power amplifiers, the main circuit, auxiliary circuit, and post-matching network are usually designed separately. Further adjustments are made after these steps are completed, resulting in a complex and cumbersome design method. Furthermore, the regular structure output network used in traditional designs is prone to relatively low performance, making it difficult to meet application requirements.

[0004] To address the aforementioned problems, this invention improves the overall optimization design of the Doherty output network, providing a method for the overall optimization design of a Doherty power amplifier output network. The designed Doherty power amplifier output network structure is as follows: Figure 2 As shown in the figure, the overall optimization design method for the irregular structure output network of the Doherty power amplifier proposed in this invention first calculates the required S-parameters of the 3-port output network based on the power ratio and impedance conditions under saturated output and power back-off. Second, a multi-objective evolutionary algorithm is used to call HFSS simulation software to perform electromagnetic simulation of the irregular circuit. Then, the simulation data is output to ADS simulation software through the application programming interface for joint simulation and optimization of the 3-port network. Finally, the optimal irregular structure output network of the Doherty power amplifier is obtained. This invention has significant research value and importance in improving the power back-off efficiency and expanding the operating bandwidth of the Doherty power amplifier. Summary of the Invention

[0005] The purpose of this invention is to provide a method for overall optimization design of the output network of a Doherty power amplifier. It utilizes irregular circuit structures for overall optimization design, thereby more effectively simplifying the design process, improving the degree of freedom in optimization design, and enhancing the performance indicators of the Doherty power amplifier.

[0006] To solve the above technical problems, the specific technical solution adopted by the present invention is as follows: A method for overall optimization design of Doherty power amplifier output network, comprising: Step S1: Use load-pull simulation to obtain the equal power circle and equal efficiency circle at each design frequency point in the broadband power amplifier tube, determine the overlapping area of ​​the equal power circle and equal efficiency circle, obtain the target load impedance area, and determine the saturation and back-off impedance of the main and auxiliary power amplifier tubes; use small-signal simulation to obtain the open-circuit impedance of the auxiliary power amplifier tube at each design frequency point; calculate the S-parameters of the 3-port network based on the above simulation parameters. Step S2: Determine the relevant parameters of the matching network continuous polyline structure, including the number of microstrip line segments, the length and width of each microstrip line segment, and the number of connection points; Step S3: Determine the relevant parameters of the multi-objective optimization algorithm, including the objective function setting, the number of objectives, the population size, and the number of iterations; Step S4: Randomly generate using a multi-objective optimization algorithm. n The code corresponds to each continuous polyline structure; Step S5: Initialize the current optimization algebra number. j= 1; Step S6: Initialize the current optimized individual ID. i= 1; Step S7, output the first... i The code for each individual, using VB Script program call HFSS , for the j The generation i Modeling and analysis of each individual; Step S8, Read HFSS Simulation analysis results; Step S9: Import the simulation analysis results from step S8. ADS In S Parameter controls, accessed via application programming interface (API) calls. ADS Perform co-simulation; Step S10, Read ADS Simulation analysis results; Step S11, calculate the first... i The fitness value of each individual, and let i Add 1; Step S12: Determine the ID of the current individual. i Is it greater than the population size? nIf not, proceed to step S7; if yes, proceed to step S13. Step S13: Determine the number of the current algebra. j Is it greater than the set number of iterations? m If not, proceed to step S14; if yes, proceed to step S15. Step S14, let j Add 1, and use a multi-objective optimization algorithm to generate the first... j Replace the individual and proceed to step S6; Step S15: Output the optimal Doherty power amplifier irregular output network structure.

[0007] Furthermore, step S1 includes the following steps: S1.1 Select the center frequency point in the design frequency band as the design frequency point; S1.2 Obtain the equal power circle and equal efficiency circle of the power amplifier tube design frequency using load-pulling technology, and determine the output power as follows. P required The equal power circle and efficiency are DE required The overlapping region of the iso-efficiency circles; S1.3 Select the saturated output impedance of the main and auxiliary circuits within the overlapping region. Z C,SAT , Z P,SAT and main circuit backoff impedance Z C,OPBO And calculate the ratio of the saturated output power of the auxiliary road to the saturated output power of the main road. α ; S1.4 Obtain the open-circuit impedance of the auxiliary power amplifier using small-signal simulation techniques. Z P,OUT ; S1.5 Calculate the S-parameter matrix based on the above parameters. The S-parameter matrix is ​​calculated according to the following formula. ; in, and They are and phase, As free variables, in Internal selection, and The phase values ​​are calculated using the following formulas: ; in, and They are and The modulus, and They are and The phase; S1.6 Select other frequency points in the frequency band as design frequency points, and repeat steps S1.2, S1.3, S1.4, and S1.5.

[0008] Furthermore, step S2 includes the following steps: S2.1 Determine the number of microstrip line segments used in the main and auxiliary output matching networks and the post-matching network in the output matching network; S2.2 Determine the length and width of each microstrip line in the output matching network; S2.3 Determine the number of connection points for each microstrip line in the output matching network, wherein the number of connection points is calculated according to the following formula; ; in, These represent the width of the microstrip line and the x and y coordinates of the connection point, respectively. To control variables, change The value can make the x-coordinate in Variation within a range; Let be the initial y-coordinate of the current connection point, and That is, the initial spacing between the two connection points is 1mm, which is changed by... The value makes the distance between adjacent connection points in The changes between them.

[0009] Furthermore, step S3 includes the following steps: S3.1 Determine the number of objectives and population size for the optimization algorithm. n Number of iterations m ; S3.2 Set the optimization objective function, which is set according to the following formula; ; in, To optimize the target value, To optimize the algorithm's calculated values, since We selected the six parameters on the diagonal and above the S-parameter matrix as the optimization targets, which are respectively .

[0010] Further, step S7 includes: using VB Script call HFSS According to the j The generation iThe irregular structure encoding of each individual is used to model and analyze the output matching network and the post-matching network respectively, and the 2-port S-parameters of the matching network are obtained; the 2-port S-parameters of each output matching network are output to the local machine.

[0011] Further, step S9 includes: importing the 2-port S-parameters of the output matching network into the S-parameter control in ADS; using the application programming interface to call ADS for simulation to obtain the 3-port network S-parameters of the output network; and outputting the 3-port network S-parameters to the local machine.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) This invention simplifies the design process of Doherty amplifiers. Traditional Doherty amplifier designs typically involve designing each matching network separately and then combining them, which is cumbersome and makes it difficult to simultaneously guarantee saturation and backoff performance. Based on the above background, this invention treats the Doherty amplifier output combining network as a whole and designs it using a 3-port network analysis method, which simplifies the design steps and ensures optimal performance at both backoff and saturation power.

[0013] (2) This invention is beneficial for improving power back-off efficiency and expanding operating bandwidth. Traditional Doherty amplifier designs are often based on regular circuits, but the solution possibilities for regular structures are limited, the degree of design freedom is low, and it is difficult to meet the ever-increasing bandwidth and performance requirements. Based on the above background, this invention adopts irregular circuit structures, which improves the degree of design freedom while ensuring power back-off efficiency and operating bandwidth. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the output network structure of a conventional Doherty power amplifier.

[0015] Figure 2 This is a schematic diagram of the Doherty power amplifier output network structure of the present invention.

[0016] Figure 3 This is a flowchart of the overall optimization design method for the Doherty power amplifier output network of the present invention.

[0017] Figure 4 This is the target load impedance selection area used in this invention, with a center frequency of 2.0 GHz as an example.

[0018] Figure 5 This is a simplified model of the irregular structure, i.e., the continuous broken line structure, used in this invention.

[0019] Figure 6 This is a schematic diagram of the irregular modeling using HFSS in this invention.

[0020] Figure 7 This is a schematic diagram of the ADS used in this invention for 3-port simulation using the S-parameter control.

[0021] Figure 8 This is a schematic diagram of a Doherty power amplifier based on overall optimization of the output network, according to an embodiment of the present invention.

[0022] Figure 9 This invention relates to the variation of gain and efficiency at specific frequencies of a Doherty power amplifier with output power, based on overall optimization of the output network, according to an embodiment of the present invention.

[0023] Figure 10 This invention aims to optimize the saturated output power and operating efficiency of the Doherty power amplifier within its operating frequency band based on the overall optimization of the output network in this embodiment. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that the technical solution and design principle of the present invention will be described in detail below with reference to only one preferred technical solution, but the protection scope of the present invention is not limited thereto.

[0025] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

[0026] Figure 2 The diagram shows the overall structure of the Doherty power amplifier output network designed in this invention. Figure 3 The flowchart of the overall optimization design method for the Doherty power amplifier output network of the present invention includes: Step S1, with Figure 4 Taking the center frequency of 2.0GHz as an example, load-pull simulation is used to obtain the equal power circle and equal efficiency circle of each design frequency point in the broadband power amplifier tube, determine the overlapping area of ​​the equal power circle and equal efficiency circle, obtain the target load impedance area, and determine the saturation and back-off impedance of the main and auxiliary power amplifier tubes; small-signal simulation is used to obtain the open-circuit impedance of the auxiliary power amplifier tube at each design frequency point; based on the above simulation parameters, the S-parameters of the 3-port network are calculated. Step S2: Determine the relevant parameters of the matching network continuous piecewise linear structure, including the number of microstrip line segments, the length and width of each microstrip line segment, and the number of connection points, such as... Figure 5 The image shows a simplified model of a continuous broken line structure. Step S3: Determine the relevant parameters of the multi-objective optimization algorithm, including the objective function setting, the number of objectives, the population size, and the number of iterations; Step S4: Randomly generate using a multi-objective optimization algorithm. nThe code corresponds to each continuous polyline structure; Step S5: Initialize the current optimization algebra number. j= 1; Step S6: Initialize the current optimized individual ID. i= 1; Step S7, output the first... i The code for each individual, using VB Script program call HFSS , for the j The generation i Modeling and analyzing each individual, such as Figure 6 The image shown is a schematic diagram of irregular modeling in HFSS; Step S8, Read HFSS Simulation analysis results; Step S9: Import the simulation analysis results from step S8. ADS In S Parameter controls, accessed via application programming interface (API) calls. ADS Perform co-simulation, such as Figure 7 The diagram shown is a simulation schematic of a 3-port S-parameter control. Step S10, Read ADS Simulation analysis results; Step S11, calculate the first... i The fitness value of each individual, and let i Add 1; Step S12: Determine the ID of the current individual. i Is it greater than the population size? n If not, proceed to step S7; if yes, proceed to step S13. Step S13: Determine the number of the current algebra. j Is it greater than the set number of iterations? m If not, proceed to step S14; if yes, proceed to step S15. Step S14, let j Add 1, and use a multi-objective optimization algorithm to generate the first... j Replace the individual and proceed to step S6; Step S15: Output the optimal Doherty power amplifier irregular output network structure.

[0027] In a preferred embodiment of the present invention, step S1 includes the following steps: S1.1 Select the center frequency point in the design frequency band as the design frequency point; S1.2 Obtain the equal power circle and equal efficiency circle of the power amplifier tube design frequency using load-pulling technology, and determine the output power as follows. P required The equal power circle and efficiency are DErequired The overlapping region of the iso-efficiency circles; S1.3 Select the saturated output impedance of the main and auxiliary circuits within the overlapping region. Z C,SAT , Z P,SAT and main circuit backoff impedance Z C,OPBO And calculate the ratio of the saturated output power of the auxiliary road to the saturated output power of the main road. α ; S1.4 Obtain the open-circuit impedance of the auxiliary power amplifier using small-signal simulation techniques. Z P,OUT ; S1.5 Calculate the S-parameter matrix based on the above parameters. The S-parameter matrix is ​​calculated according to the following formula. ; in, and They are and phase, As free variables, in Internal selection, and The phase values ​​are calculated using the following formulas: ; in, and They are and The modulus, and They are and The phase; S1.6 Select other frequency points in the frequency band as design frequency points, and repeat steps S1.2, S1.3, S1.4, and S1.5.

[0028] In a preferred embodiment of the present invention, step S2 includes the following steps: S2.1 Determine the number of microstrip line segments used in the main and auxiliary output matching networks and the post-matching network in the output matching network; S2.2 Determine the length and width of each microstrip line in the output matching network; S2.3 Determine the number of connection points for each microstrip line in the output matching network, wherein the number of connection points is calculated according to the following formula; ; in, These represent the width of the microstrip line and the x and y coordinates of the connection point, respectively. To control variables, change The value can make the x-coordinate in Variation within a range; Let be the initial y-coordinate of the current connection point, and That is, the initial spacing between the two connection points is 1mm, which is changed by... The value makes the distance between adjacent connection points in The changes between them.

[0029] In a preferred embodiment of the present invention, step S3 includes the following steps: S3.1 Determine the number of objectives and population size for the optimization algorithm. n Number of iterations m ; S3.2 Set the optimization objective function, which is set according to the following formula; ; in, To optimize the target value, To optimize the algorithm's calculated values, since We selected the six parameters on the diagonal and above the S-parameter matrix as the optimization targets, which are respectively .

[0030] In a preferred embodiment of the present invention, step S7 includes: using VB Script call HFSS According to the j The generation i The irregular structure encoding of each individual is used to model and analyze the output matching network and the post-matching network respectively, and the 2-port S-parameters of the matching network are obtained; the 2-port S-parameters of each output matching network are output to the local machine.

[0031] In a preferred embodiment of the present invention, step S9 includes: importing the 2-port S-parameters of the output matching network into the S-parameter control in ADS; using the application programming interface to call ADS for simulation to obtain the 3-port network S-parameters of the output network; and outputting the 3-port network S-parameters to the local machine.

[0032] The present invention will be further illustrated below with a specific embodiment.

[0033] This embodiment uses Wolfspeed CGH40010F GaN HEMT power amplifier transistors to design a 1.2-2.8 GHz broadband Doherty power amplifier. The board material is... εr = 3.5, h =30 mil Rogers 4350B dielectric substrate.

[0034] First, based on the simulation described in step S1, the saturation and back-off impedances, open-circuit impedances, and saturation output power ratios at nine frequency points every 200MHz within the 1.2-2.8GHz range are obtained. The parameters corresponding to each frequency point are shown in Table 1. Based on these parameters, the S-parameter matrix corresponding to each frequency point is calculated, as shown in Table 2. Second, according to step S2, the number of microstrip line segments used in the main and auxiliary output matching networks and the post-matching network in the output matching network is determined. Finally, using the above S-parameters as the objective, the overall optimization design of the Doherty power amplifier output network is performed according to steps S3 to S15. In this embodiment, the optimization algorithm selected in steps S4 and S14 is a decomposition-based multi-objective evolutionary algorithm, yielding... Figure 2 The results of the irregular output matching network for the Doherty power amplifier are shown. A similar method can be used to derive the input matching network design requirements from the source impedance, and then optimize the design of the irregular structure input matching network, ultimately yielding the following... Figure 8 The Doherty amplifier shown.

[0035] Figure 9 and Figure 10 These figures show the gain and efficiency at five specific frequency points of a 1.2-2.8 GHz broadband power amplifier designed using the Doherty power amplifier output network overall optimization design method proposed in this invention, as well as the saturated output power and efficiency within the operating frequency band. Figure 9 As can be seen, the gain fluctuations at each selected frequency point are small, and the backoff efficiency is greater than 50% for all of them. From Figure 10 As can be seen, the saturated output power in the operating frequency band is approximately 43.1-44.1 dBm, the saturation efficiency is approximately 50.1-73.4%, the efficiency at 6 dB power back-off is approximately 50.1-55.0%, and the relative bandwidth is 80%, which can effectively meet the needs of practical applications.

[0036] Table 1 Design parameters for a 3-port output network

[0037] Table 2 S-parameters of a 3-port output network

Claims

1. A method for overall optimization design of the output network of a Doherty power amplifier, characterized in that, Includes the following steps: Step S1: Use load-pull simulation to obtain the equal power circle and equal efficiency circle at each design frequency point in the broadband power amplifier tube, determine the overlapping area of ​​the equal power circle and equal efficiency circle, obtain the target load impedance area, and determine the saturation and back-off impedance of the main and auxiliary power amplifier tubes; use small-signal simulation to obtain the open-circuit impedance of the auxiliary power amplifier tube at each design frequency point; calculate the S-parameters of the 3-port network based on the above simulation parameters, and use the above S-parameters as the target. Step S2: Determine the relevant parameters of the matching network continuous polyline structure, including the number of microstrip line segments, the length and width of each microstrip line segment, and the number of connection points; Step S3: Determine the relevant parameters of the multi-objective optimization algorithm, including the objective function setting, the number of objectives, the population size, and the number of iterations; Step S4: Randomly generate using a multi-objective optimization algorithm. n The code corresponds to each continuous polyline structure; Step S5: Initialize the current optimization algebra number. j= 1; Step S6: Initialize the current optimized individual ID. i= 1; Step S7, output the first... i The code for each individual, using VB Script program call HFSS , for the j The generation i Modeling and analysis of each individual; Step S7 includes: using VB Script call HFSS According to the j The generation i The irregular structure encoding of each individual is used to model and analyze the output matching network and the post-matching network respectively, and the 2-port S-parameters of the matching network are obtained; the 2-port S-parameters of each output matching network are output to the local machine. Step S8, Read HFSS Simulation analysis results; Step S9: Import the simulation analysis results from step S8. ADS In S Parameter controls, accessed via application programming interface (API) calls. ADS Perform co-simulation; step S9 includes: importing the 2-port S-parameters of the output matching network into the S-parameter control in ADS; using the application programming interface to call ADS for simulation to obtain the 3-port network S-parameters of the output network; and outputting the 3-port network S-parameters to the local machine. Step S10, Read ADS Simulation analysis results; Step S11, calculate the first... i The fitness value of each individual, and let i Add 1; Step S12: Determine the ID of the current individual. i Is it greater than the population size? n If not, proceed to step S7; if yes, proceed to step S13. Step S13: Determine the number of the current algebra. j Is it greater than the set number of iterations? m If not, proceed to step S14; if yes, proceed to step S15. Step S14, let j Add 1, and use a multi-objective optimization algorithm to generate the first... j Replace the individual and proceed to step S6; Step S15: Output the optimal Doherty power amplifier irregular output network structure.

2. The overall optimization design method for the Doherty power amplifier output network according to claim 1, characterized in that, Step S1 includes the following steps: S1.1 Select the center frequency point in the design frequency band as the design frequency point; S1.2 Obtain the equal power circle and equal efficiency circle of the power amplifier tube design frequency point through load pulling technology, and determine the overlapping area of ​​the equal power circle and the equal efficiency circle; S1.3 Select the saturated output impedance of the main and auxiliary circuits within the overlapping region. Z C,SAT , Z P,SAT and main circuit backoff impedance Z C,OPBO And calculate the ratio of the saturated output power of the auxiliary road to the saturated output power of the main road. α ; S1.4 Obtain the open-circuit impedance of the auxiliary power amplifier using small-signal simulation techniques. Z P,OUT ; S1.5 Calculate the S-parameter matrix based on the above parameters. The S-parameter matrix is ​​calculated according to the following formula. ； in, and They are and phase, As free variables, in Internal selection, and The phase values ​​are calculated using the following formulas: ； in, and They are and The modulus, and They are and The phase; S1.6 Select other frequency points in the frequency band as design frequency points, and repeat steps S1.2, S1.3, S1.4, and S1.

5.

3. The overall optimization design method for the Doherty power amplifier output network according to claim 1, characterized in that, Step S2 includes the following steps: S2.1 Determine the number of microstrip line segments used in the main and auxiliary output matching networks and the post-matching network in the output matching network; S2.2 Determine the length and width of each microstrip line in the output matching network; S2.3 Determine the number of connection points for each microstrip line in the output matching network, wherein the number of connection points is calculated according to the following formula; ； in, These represent the width of the microstrip line and the x and y coordinates of the connection point, respectively. To control variables, change The value can make the x-coordinate in Variation within a range; Let be the initial y-coordinate of the current connection point, and That is, the initial spacing between the two connection points is 1mm, which is changed by... The value makes the distance between adjacent connection points in The changes between them.

4. The overall optimization design method for the Doherty power amplifier output network according to claim 1, characterized in that, Step S3 includes the following steps: S3.1 Determine the number of objectives and population size for the optimization algorithm. n Number of iterations m ; S3.2 Set the optimization objective function, which is set according to the following formula; ； in, To optimize the target value, To optimize the algorithm's calculated values, since We selected the six parameters on the diagonal and above the S-parameter matrix as the optimization targets, which are respectively .

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