A two-stage 0.9–2 GHz GaN power amplifier using commensurate transmission line

An semi-analytic method is proposed to reduce the complexity of two-stage matching network (MN). It is also improved by adding a variable in the power supply branch for cutting down the size of MN. The first stage operates in a deep class AB mode, which would contribute to reshape the voltage form at gate of the second stage. In this way, the two-stage power amplifier without isolator could also achieve a good gain and efficiency performance. The experimental results show that the large signal gain is 31.3–35.5 dB with output power of 39.2–41.9 dBm in the band of 0.9–2 GHz and corresponding drain efficiency is 37.4–62%. And linearity performance is also evaluated via stimulus of 5 MHz WCDMA and 20 MHz LTE signals.