GaN high power amplifier MMIC for 30W Compact Doherty amplifier for LTE active antenna system

In this paper, an high efficiency and high output power amplifier MMIC based on 0.25 um GaN HEMT proress is presented. The MMIC has been designed with an output impedance moving technique to help a Doherty amplifier to be implemented in a small area. A compact Doherty amplifier for an active antenna system of a LTE base station has been implemented with the developed GaN high power amplifier (HPA) MMIC. The Doherty amplifier has been measured with power added efficiency (PAE) of 42 % at 7 dB back-off output power of 38 dBm, the maximum PAE of 55 % at the peak saturated output power of 45dBm in the frequency range 2.62 GHz ~ 2.69 GHz. The Doherty amplifier has the linear gain more than 27 dB in the frequency range and ACLR performance better than -31 dBc with the 20 MHz bandwidth WCDMA signal without helping any linearization technique. The Doherty amplifier has been assembled in PCB with the size of 25 mm × 25 mm including input LTCC divider and output combining networks.