A Low-Power K-Band CMOS VCO With Four-Coil Transformer Feedback

A K-band low-power and low-phase-noise voltage-controlled oscillator (VCO) is presented in this letter. By utilizing four-coil transformer feedback and forward body bias topology, good performances are obtained under a low-power supply with a 5.1% tuning range and a phase noise of -109.8 dBc/Hz at 1 MHz offset from the 21.37-GHz carrier frequency. The core circuit of this VCO only consumes 3.5 mW with a 0.6-V supply voltage and a 0.55-V body bias.