Submillimeter‐wave InPHBT power amplifier using impedance‐transforming two‐way balun

Abstract

ABSTRACTIn this letter, a submillimeter‐wave power amplifier (PA) is presented using a 250 nm InP HBT technology. To obtain high output power, a two‐way power combiner with differential outputs is proposed using multimetal layers. This two‐way balun has an embedded impedance‐transformation function, which enables to design broadband and low‐loss impedance matching networks of a PA. The back‐to‐back connected balun shows a measured insertion loss of 1.2 dB at 296 GHz, including the losses of RF pads. The balanced PA using cascode power cells and the baluns exhibits a measured small‐signal gain of 9.0 dB with broad bandwidth, and the measured output power of 10.0 dBm with a gain of 6.0 dB and drain efficiency of 5.4% at 296 GHz. The chip size is as small as 0.49 mm × 0.41 mm including DC and RF pads. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1831–1834, 2015