A Wideband, Dual-Path, Millimeter-Wave Power Amplifier With 20 dBm Output Power and PAE Above 15% in 130 nm SiGe-BiCMOS Yi Zhao, Student Member , IEEE, and John R. Long , Member , IEEE

Abstract

A frequency-scalable, three-stage, transformer- coupled millimeter-wave power ampli fier (PA) is implemented in 130 nm SiGe-BiCMOS. Differential common-base gain stages extend collector-emitter breakdown voltage beyond 3 V , while collector-emitter neutralizatio n increases reverse isolation and stability. Monolithic self-shielded transformers designed for low insertion loss and compact dim ensions on-chip include: a 2:4 input power splitter, a 4:1 output balun combiner and inter-stage coupling transformers. The balun combiner and fully-differential splitter are compensated for imbalances caused by parasiti c interwinding capacitance, and simulations predict better than 3% uniformity between re flected port-to-port impedances at 60 GHz. Simulated impedance uniformity is within 6% from 55 –65 GHz, and insertion loss of the 0.015 mm combiner prototypes at 60 GHz is below 1 dB. The 0.72 mm 60 GHz-band PA realizes a measured peak small- signal gain higher than 20 dB with over 10 GHz 3d Bb a n d w i d t h . Reverse isolation is better than 51 dB from 50–65 GHz and the PA is unconditionally stable. It consumes 353 m W (quiescent) from a 1 . 8Vs u p p l ya n dt h ea c t i v ea r e ai s0 . 2 5m m . Maximum output power and peak power-added ef ficiency (PAE) are 20.1 dBm and 18% at 62 GHz, respectiv ely. An up-banded 7 9–87.5 GHz PA is also implemented to verify frequen cy scalability of the design. The 0.23 mm active area 79 GHz PA prototype produces 18 dBm sat- urated output power and