星载功率放大器NPR测试方法研究

Study on NPR test method of spaceborne power amplifier

针对星载功率放大器噪声功率比(noise power ratio,NPR)指标缺乏考核方法的问题,根据多载波非线性工作原理,使用基于数字I/Q调制的方法在Matlab里编辑基带波形文件,形成具有陷波的宽带多载波信号,依据频谱仪采样的数字预处理方法校准宽带多载波信号的幅度平坦度,调节矢量信号源I/Q两路的功率偏置进而调整陷波的深度来生成满足条件的宽带多载波激励信号。通过输入放大器该校正后的激励信号、分析被测放大器件输出端频谱陷波内产生的互调失真分量的测试方法,设计了通过矢量信号源和频谱仪进行测试的方案。根据方案所搭建的测试系统,完成了某K频段行波管放大器(主载波频率为19800MHz,带宽为80MHz)的测试验证。研究结果表明,提出的NPR测试方法有效可行,为考核星载微波功率放大器NPR指标提供了具体的测试方法。

In order to solve the problem that the spaceborne power amplifier noise power ratio index lacks the assessment method,this paper is based on the principle of multicarrier nonlinear operation,by using the method based on digital I/Q modulation to edit the baseband waveform file with Matlab to form a wideband multicarrier signal with notch,and calibrating the amplitude flatness of wideband multicarrier signal according to the digital preprocessing method of frequency spectrograph sampling,and adjusting the I/Q power offset of vector signal generator to change the depth of notch,the wideband multicarrier excitation signal satisfying the test conditions is finally generated.By inputting the excitation signal to the power amplifier and analyzing the intermodulation distortion components generated in the notch of the output of the power amplifier under test,a test scheme is designed by means of vector signal generator and spectrum analyzer.According to the test system built by the scheme,this test method to a K-band traveling-wave tube amplifier(the main carrier frequency is 19800 MHz,the bandwidth is 80 MHz)is tested and verified.The results show that the noise power ratio test method proposed in this paper is effective and feasible,and provide a specific test method for evaluating NPR index of spaceborne microwave power amplifier.