星用S频段20W高增益线性化功率放大器的研究

Research on S-band high-gain and linearity SSPA for satellite with 20W output power

为了满足卫星通信的特殊需求,研制完成了一款S波段高增益线性化固态功率放大器。固放输出功率为20 W。为了解决高增益的要求,固放内设计完成了小信号的高增益MMIC电路,固放增益达到95 dB,但仍能稳定工作。为了提高固放的线性度,在固放中设计预失真电路,改善了固放的线性化指标:IMD3(三阶交调)改善了3.5 dB,NPR改善了约2.1 dB,满足了系统的使用要求。固放主要包括两部分:小信号部分(LPS)采用MMIC器件,优化了整机体积和重量;高功率部分(HPS)采用内匹配的砷化镓场效应晶体管。通过优化放大器的工作点,减小器件端口阻抗失配,提高了放大器的工作效率5%。经过最终测试结果对比,固放性能优良,几乎达到国外同类产品的指标。

To meet the special requirement of satellite communication, the s-band solid state power amplifier （ SS- PA） with high gain and linearity is developed. The SSPA delivers more than 20W of output power. An MMIC circuit in SSPA for higher gain is designed, and finally, the power gain of SSPA is greater than 95 dB. A pre-distortion circuit is designed to improve the nonlinear characteristic, and the IMD3 of SSPA is improved by 3.5 dB and NPR by 2.1 dB. This result shows that the performance of SSPA is better than demanded. In the SSPA design, the low power section （LPS） of SSPA is realized by MMICs device for optimum cubage and weight. Additionally, the high power section （HPS） of SSPA is realized by internal-match GaAs device. And many techniques are used to enhance the efficiency of SSPA by 5% , such as optimization of bias-point and decreasing mismatch of device port. The RF test results are shown at the end, which proves that the SSPA has the same excellent performance as similar SSPA abroad.