X-band and K-band low-phase-noise VCOs using SiGeBiCMOS technology

From the past two decades, SiGe transistors have been identified as excellent candidates to match requirements both for high purity signal generation and high frequency applications. Moreover, SiGe BiCMOS technology benefits from CMOS devices that allow high integration levels for monolithic microwave integrated circuit (MMIC) phase locked loop (PLL) systems. This work focuses on the only analogue circuit of a PLL: the voltage controlled oscillator (VCO) which is one of the cornerstones of a transceiver because its stability mainly influences the data rate of the channel. X-band and K-band VCOs are investigated. Design rules are compared for two different topologies in the X-band. The K-band VCO is also designed to assess the technology behaviour for higher frequencies. State-of-the-art results are obtained and compared with the best published performances to date. New expressions of a figure of merit (FOM) are proposed to provide an accurate comparison between designs featuring scattered performances.