In support of emerging millimeter-wave communications systems, Michael Aust and associates from Northrop Grumman (Redondo Beach, CA) have developed a high-efficiency monolithic power amplifier capable of 2.8 W (+34.5 dBm) output power at Q-band frequencies from 42 to 46 GHz. The amplifier features power-added efficiency (PAE) of 23 to 26 percent when operated at 5 V and 250 mA/mm of device periphery. It achieved maximum PAE of 24 to 29 percent and output power of +33.6 to +34 dBm when biased at +5 VDC and 125 mA/mm.

In-phase binary power combiners/dividers with impedance matching are employed to maintain high power and PAE. The Wilkinson combiner was designed to minimize RF loss at the expense of bandwidth and isolation. The four-way output combiner achieved input return loss of better than 33 dB with simulated insertion loss of less than 0.5 dB. The output return loss was better than 35 dB and the isolation was better than 21 dB. See “A 2.8-W Q-Band High-Efficiency Power Amplifier,” IEEE Journal of Solid-State Circuits, October 2006, Vol. 41, No. 10, p. 2241.