A High-Linear Ka-Band Power Amplifier with Diode-Based Analogue Predistortion

This paper presents an analogue predistortion (APD) technique to improve the linearity of power amplifiers (PAs) with little penalty to output power and efficiency. The technique compensates the phase distortion of the PA through a transistor-based diode, which is embedded in the input matching network. As a proof of concept, a 3-stage 28GHz PA has been implemented in a 0.1um GaAs pHEMT process. Tested with a 256-QAM 100MHz bandwidth signal, the PA shows 23dB gain, 20.6dBm average output power, 10% average power-added efficiency (PAE), and -30dB error vector magnitude (EVM).