A linear dual-control-voltage K-band VCO with a Gilbert frequency multiplier

Abstract

This letter presents a linear K-band voltage-controlled oscillator (VCO) with a Gilbert frequency multiplier. Three pairs of varactors form a varactor compensation topology to broaden the linear frequency range and improve the VCO linearity. The varactors are tuned by two control voltages so that the frequency can be tuned in a wide range continuously. A Gilbert cell-based frequency multiplier is implemented to achieve the desired frequency with low phase noise. Fabricated in 0.13μm CMOS technology, the total area of the proposed VCO is approximately 0.28mm². This VCO achieves a tuning range of 21.4 to 25GHz (15.5%), and a linear tuning range between 0.5V to 1.8V control voltage, the mismatch of the VCO gain is only 9.1% in the linear tuning range. The output phase noise reaches -75.13dBc/Hz at 100kHz offset frequency and -108.53dBc/Hz at 1MHz offset frequency from the 24.2GHz carrier frequency, respectively.