A flat gain/power responses 618 GHz power amplifier MMIC with high PAE by using transformer networks

A two‐stage power amplifier monolithic microwave integrated‐circuit, operating between 6 and 18 GHz by implementing AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistors is presented. This devised power amplifier has demonstrated flat gain and power responses over a wide bandwidth by employing a novel design approach of combined prematched LC network and multisection impedance transformer network. Superior gain flatness of ±1.5 dB and power flatness of ±1.1 dBm over 6–18 GHz bandwidth, respectively, have been successfully achieved. With a dual‐bias configuration, the power amplifier shows average small‐signal gain of 13 dB, 2‐dB gain compression power of 32.4 dBm and high power‐added efficiency (PAE) of 24–34.5%. In additions, by using off‐chip combiner techniques, the balanced power amplifier shows superior maximum output power of 36.5 dBm and PAE of 22–33.1%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 205–208, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23033