Supply-Scaling for Efficiency Enhancement in Distributed Power Amplifiers

Distributed amplifiers (DAs) feature large bandwidth but relatively low gain and power efficiency. This paper presents a supply-scaling technique to improve the efficiency of a mm-wave DA while maintaining a broadband 50\Omega match. An analysis of interstage load modulation and the effects of shunt dc-feed inductors on distributed operation is provided. A single-ended, eight-stage DA is designed in a 90 nm SiGe BiCMOS process. The fabricated amplifier has a gain of 12 dB over a 3 dB bandwidth from 14-105 GHz. The measured peak output power is 17 dBm with a peak power-added efficiency (PAE) of 12.6% at 50 GHz and 3 dB power bandwidth greater than 70 GHz. The DA occupies an area of 2.65 mm × 0.57 mm, and total dc power consumed from four scaling voltage supplies is 297 mW.