A 240 W doherty GaAs power FET amplifier with high efficiency and low distortion for W-CDMA base stations

Abstract

An L/S-band 240 W Doherty GaAs FET amplifier with high efficiency and low distortion has been successfully developed. The amplifier employed a simple 2-way Doherty configuration to our plastic-packaged GaAs heterojunction FETs (HJFETs). We optimized load impedance shift of the main and the peak amplifiers as a function of input power level utilizing load-pull measurement and large signal simulation. The developed Doherty amplifier demonstrated low adjacent channel leakage power ratio (ACPR) of less than -34 dBc with a power-added efficiency (PAE) of 34% at an output power (Pout) of 45 dBm with a W-CDMA signal at 2.14 GHz. It also showed 53.8 dBm saturation output power with 11.2 dB linear gain. It achieved efficiency enhancement more than 11% compared to the conventional push-pull configuration under the same ACPR conditions. To our knowledge, these represent the best results ever reported among the high power FET amplifiers for W-CDMA base stations.