A broadband high efficiency monolithic power amplifier with GaAs HBT

Abstract

A broadband single-stage power amplifier (PA) is presented in this paper. The proposed PA is designed and implemented using 2-µm GaAs HBT process to be targeted for wide range handset devices at operating frequency around 5 GHz. In this PA, mixed matching networks are designed with transmission lines (TLs) and lumped capacitors for bandwidth enhancement. In conjunction with feedback technology and diode-based bias circuit allow us to achieve the high efficiency and comparable linearity at a low supply voltage. Measured small signal flatten gain, maximum average output powers are all better than 10 dB and 22.5 ± 0.5 dBm over 4.2–5.8 GHz (32%), respectively. The prototype achieves a peak power-added efficiency (PAE) of 47.2% at 5 GHz, and the third-order intermodulation distortion (IMD3) performance below −38 dBc up to saturation power of 23.2 dBm. This work has potential for wideband high efficiency Doherty PA (DPA) used in future mobile communication system.