Improving Power Amplifier Efficiency and Linearity Using a Dynamically Controlled Tunable Matching Network

This paper presents a tunable matching network that enhances both efficiency and linearity of power amplifiers (PAs). A medium-power amplifier with a varactor-based matching network is designed, fabricated, and tested. It is demonstrated that not only the power efficiency at reduced drive levels can be improved but also the AM-AM and AM-PM distortions of the PA are reduced when the tunable matching network is biased according to the input drive level. Moreover, under 3GPP WCDMA modulated input, the PA with a dynamically controlled tunable matching network achieves up to 5% improvement in drain efficiency when compared with a PA employing a fixed matching network.