Compensation of the Pulse-to-Pulse Instability of GaN HEMT-Based Power Amplifiers

In this paper we describe a method for compensating the pulse-to-pulse instability of GaN high-electron-mobility transistor (HEMT)-based power amplifiers (PAs) caused by electron-trapping effects. The method consists in generating a compensation signal based on measured data and using it to offset the dynamic threshold voltage modulation caused by the charge and discharge of the HEMT’s traps. This method was verified with a pulsed radar waveform for moving target indication on a 15 W GaN HEMT-based PA, achieving an improvement of the peak output power of 0.85 dB and an improvement of the pulse-to-pulse amplitude stability of over 20 dB.