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 0.13 µm CMOS technology, the total area of the proposed VCO is approximately 0.28 mm 2 . This VCO achieves a tuning range of 21.4 to 25 GHz (15.5%), and a linear tuning range between 0.5 V to 1.8 V control voltage, the mismatch of the VCO gain is only 9.1% in the linear tuning range. The output phase noise reaches −75.13 dBc/Hz at 100 kHz offset frequency and −108.53 dBc/Hz at 1 MHz offset frequency from the 24.2 GHz carrier frequency, respectively.