Design and Optimization of 20 GHz LC-VCOs in SiGe:C BiCMOS Technology

The design and analysis of fully integrated voltage controlled oscillators (VCO) for 20 GHz low cost and low power communication system is presented in this paper. Two differential topologies have been studied: balanced Colpitts VCO and LC-VCO using a cross-coupled differential pair. We have focussed on oscillation frequency, tuning range, phase noise, and output power optimization and buffer stage specifications. SiGe:C hetero-junction bipolar transistors of f_T=55 GHz have been used and produced with a monolithic BiCMOS technology.