A high power active circulator using GaN MMIC power amplifiers

Abstract

This paper presents a 2.4 GHz hybrid integrated active circulator consisting of three power amplifiers and three PCB-based Wilkinson power dividers. The power amplifiers were designed and fabricated in a standard 0.35-μm AlGaN/GaN HEMT technology, and combined with three traditional power dividers on FR4 using bonding wires. Due to the isolation of power dividers, the isolation between three ports is achieved; meanwhile, due to the unidirectional characteristics of the power amplifiers, the nonreciprocal transfer characteristic of the circulator is realized. The measured insertion gain of the proposed active circulator is about 2–2.7 dB at the center frequency of 2.4 GHz, the isolation between three ports is better than 20 dB over 1.2–3.4 GHz, and the output power of the designed active circulator achieves up to 20.1–21.2 dBm at the center frequency.