数字预失真技术对行波管发射机信号质量的影响研究

Study on the Effect of Digital Predistortion on Signal Quality of Travelling-Wave Tube Transmitter

摘要: 以数字预失真为代表的线性化技术，是提高大功率发射信号质量的重要手段。该文设计了一种数字预失真方案，研制了样机，并在X波段100 W行波管发射机上进行了实验验证，取得了对发射信号质量改善的效果：矢量误差模(EVM)从8%下降到5%，三阶交调降低约10 dB，变功率输入时通道间相位一致性改善约10°，时域峰值−3 dB宽度改善了1.33 μs。在此基础上，该文从时域、频域等角度分析了数字预失真技术对发射信号质量的改善作用。

Abstract: The linearization technology represented by digital predistortion is an important means to improve the quality of high-power transmitting signals. In this paper, a digital predistortion scheme is designed. An experimental verification is carried out on X band, 100 W travelling-wave tube (TWT) transmitter, and the improvement effect on the signal quality is achieved: error vector magnitude (EVM) falls from 8% to 5%; third-order intermodulation is reduced about 10 dB; the consistency of phase between channels is improved about 10° with different input power level; the 3 dB width of amplitude in time domain is improved by 1.33 microseconds. On this basis, the effect of digital predistortion technology on the improvement of transmitted signal quality is analyzed from the perspectives of time domain and frequency domain.