A K-Band High-Efficiency VCO Using Current Reused Technique

In this letter, we present a high-efficiency CMOS voltage control oscillator (VCO) at K-Band. In order to achieve high efficiency, we adopt center-tapped transformer and current reused technique to integrate cross couple pair and buffer amplifier. In addition, we put buffer amplifier gate bias at class AB to enhance efficiency. VCO tuning range is from 22.35 to 25.31 GHz. Across the VCO frequency range, peak output power and best efficiency are 4.37 dBm and 10.93%, respectively. Phase noise is better than -101 dBc/Hz at 1 MHz offset at all tuning range. Total dc power consumption is only 25 mW for 1.8-V supplied voltage. To our best knowledge, this VCO has excellent dc to RF efficiency at K-band.