DC-50GHz Wideband Phase-Compensated 90nm-CMOS Active Balun Design

Abstract

This manuscript explores the output phase imbalance observed in the common-gate common-source transistors, and gives a mathematical formulation in determining the length of the compensation transmission line. To demonstrate the validity of this wideband phase-compensation technique, a DC-50GHz active balun is designed using commercial 90nm-CMOS process and then measured, where the phase imbalance is less than 5 degrees while the magnitude imbalance is within 1dB. All ports are well-matched and positive gain has been sustained up to 50GHz; the output-referred 1dB compression point is around 3dBm. With 3V and 32.5mA drain bias, the total power consumption is 97.5mW. To our knowledge, this is the widest active balun ever designed with such tight output phase requirement.