一种用于K波段空间行波管模拟预失真电路的设计方法

A Design Method for Analog Predistortion Circuit of K-band TWT

空间行波管(TWT)预失真电路小型化、轻量化要求使得电路调试难度变大,迫切需要一种预失真电路精确仿真及设计方法来指导产品设计。该文在分析肖特基二极管等效电路模型基础上选择二极管MA4E2039作为非线性发生器件,并建立了MA4E2039的二极管仿真模型。之后通过分析反射式预失真电路结构,获得了影响电路性能的关键参数,并在元器件和版图联合仿真阶段对这些关键参数进行精确仿真。最后对依据仿真结果进行加工的预失真电路进行测试,发现仿真结果和电路实测结果偏差小于15%,将预失真电路与K波段行波管放大器级联实现在输入回退4 dB时3阶交调达到23.77 dBc,实现了行波管的线性化。可见该方法能够用于指导空间行波管预失真电路设计,帮助提高产品开发周期,对于预失真电路的小型化设计也有重要指导意义。

The requirement of miniaturization and lightweight of space Travelling Wave Tube(TWT)predistortion circuit makes the circuit debugging more difficult.Therefore,an accurate simulation and design method of predistortion circuit is urgently needed to guide the product design.Based on the analysis of Schottky diode equivalent circuit model,the diode MA4E2039 is selected as a nonlinear generator,and the diode simulation model of MA4E2039 is established.Then,the key parameters affecting the performance of the circuit are obtained by analyzing the structure of the reflective predistortion circuit,and these key parameters are simulated accurately in the co-simulation stage of components and layout.Finally,the pre-distortion circuit processed according to the simulation results is tested,and it is found that the deviation between the simulation results and the measured results is less than 15%.By cascading the predistortion circuit with the Kband TWTA,the third-order intermodulation reaches 23.77 dBc while the IBO=4 dB.Therefore,this method can be used to guide the design of pre-distortion circuit of space TWT,help to improve the product development cycle,and also has important guiding significance for the miniaturization design of pre-distortion circuit.