Research On Key Technologies Of X-band High-power Pulsed Power Amplifiers

A microwave power amplifier(PA)is the most critical component of microwave transmitters,and their output power determines the key parameters such as the detection range and communication rate of the wireless system.In order to meet the high-power requirements of deep-space communications and long-range early-warning,highfrequency,array-based,solid-state,multi-stage,and pulsed PAs have become the development trend.With the development of wide band gap semiconductor materials such as Ga N,the output power of X-band solid-state pulsed PAs has reached the k W-level,revealing their application potential in ultra-long-distance application scenarios.Highpower,high-gain,and pulse operation bring serious problems such as low stability,low reliability,and low efficiency.All of the above problems must be overcome for practical application.Regarding the above issues,in-depth research on the stability design technology,reliability improvement technology,efficiency improvement technology,measurement technology and modeling technology of X-band solid-state pulsed high-power amplifier(HPA)are carried out.Based on these technologies,several X-band k W-level solid-state pulsed HPAs are developed.This paper focuses on the following research work.1.In order to meet the requirements of solid-state active phased arrays,the analysis methods and design methods of single-stage PA stability,multi-stage PA stability,thermal stability,and strong field stability are established.The problem of low stability is successfully solved based on the methods.Several X-band k W-level solid-state pulsed HPAs within the λ×λ cross-section are developed.The output power of the circuits reachs2 k W and the gain exceeds 60 d B.To the author’s best knowledge,the output power density per unit cross-sectional area is the highest compared with the open literature.2.The problem of strong multi-field coupling under pulse operation of high-voltage and high-current transistors is discussed.The formation mechanism of extremely strong voltage overshoot on the rising edge of the drain voltage and the rising/falling edge of the microwave pulse is studied.In order to suppress the voltage overshoot and improve the reliability of the circuit,a variety of methods for optimizing the bias circuit and matching circuit are proposed.Measurement methods for pulsed HPA that guaranteeing accuracy and reliability are proposed.A compact high-reliability internally matched HPA is designed.Compared with the traditional discrete integrated HPA,the voltage overshoot is reduced by 50%,and the circuit area is reduced by 80%.3.To improve the efficiency of pulsed HPAs,high-power pulse modulator for drain biasing with fast rising/falling edge is designed.Besides,a novel approach called edgetriggered gate modulation(ETGM)for lowering the voltage overshoot while maintaining high efficiency is proposed.For verification,an X-band pulsed HPA prototype with an output power of ～1 k W is fabricated.An average efficiency of 39.8% and an instantaneous efficiency of 54.7% under a 1‰ duty cycle is obtained.Compared with conventional Class A/B HPA,a relative efficiency improvement of more than 23.2% is achieved with the voltage overshoot dramatically suppressed.Based on our proposed method,the contradiction between high efficiency and high reliability has been greatly relieved.