High efficiency linear GaAs MMIC amplifier for wireless base station and Femto cell applications

We have demonstrated a 1W 1.8~2.2GHz high efficiency and high linearity power amplifier that was fabricated in a InGaP hetero-junction bipolar transistor (HBT) monolithic microwave integrated circuit (MMIC) technology. The 2-stage power amplifier was biased at Class AB with 60mA quiescent current and showed 28dB gain. In conjunction with the linearization active bias circuit, harmonic trap circuits were incorporated with the matching networks to simultaneously achieve good bandwidth response, low distortion and low harmonic spurious output. The power amplifier exhibited a 45dBm output third-order intercept point (OIP3) at 5V power supply. This is one of the highest third-order intercept points reported given such a low quiescent current. The power amplifier can be used as a linear driver amplifier in wireless base station applications as well as an output stage in Femto cell or repeater applications.