A Linear Envelope Tracking Power Amplifier with Varactor-based Phase Compensation Network

This paper proposes a new varactor-based compensation method to reduce the phase distortion of the envelope tracking (ET) power amplifier (PA). Differing from the conventional method where the phase compensation network (PCN) is designed separately from the PA, the proposed method integrates the PCN into the PA input matching network, thus easing the phase compensation and avoiding the trade-off in the gain performance. Moreover, this method also reduces the cost and complexity associated with the PCN control signal generation. For verification, the proposed method is applied to a 3.5 GHz GaN PA. The simulation results reveal that, when employing the proposed method and being excited by a 10 MHz LTE signal, the ET PA can provide a good average efficiency of 55% while maintaining excellent linearity of EVM < 2 % and ACLR < -45 dBc.