High efficiency harmonically-tuned gan power amplifier for 4G applications

This paper presents the design of high efficiency harmonically-tuned gallium nitride (GaN) power amplifier (PA) based on multi-harmonics load-pull measurements. The high efficiency performance is achieved by controlling the second and third harmonic output impedances at fixed fundamental output impedance using an optimized low-loss output matching network. Measurement results demonstrate that the PA prototype achieved a peak power-added efficiency of 71% and a small-signal gain of 18 dB. Using a one-carrier Worldwide Interoperability for Microwave Access (WiMAX) signal with a 7.3 dB peak-to-average power ratio (PAPR), the digitally linearized PA exhibited an average drain efficacy of 28% at an average output power of 32.8 dBm along with -55 dBc adjacent channel power ratio at the 5 MHz offset, successfully meeting the WiMAX linearity requirements.