Octave Frequency Range Triple-band Low Phase Noise K/Ka-Band VCO with a New Dual-path Inductor

This paper presents a triple-band voltage controlled-oscillator (VCO) with a new dual-path inductor. The change in inductance value of the proposed dual-path inductor is large while maintaining high Q, enabling to achieve low phase noise oscillation with octave frequency range. The inductances in the two modes of operation can be set independently, depending on the target frequencies. The inductance change is used as a coarse frequency tuning, while fine tuning is realized by a 2-bit capacitor bank with a small size varactor. As a proof of concept, a VCO in class-D biasing with the dual-path inductor has been implemented in a 65 nm CMOS process. The VCO achieves oscillation at three different frequency bands centered at 19, 28, and 36 GHz, while maintaining good phase noise and low power consumption. Measurement results show a peak figure of merit (FoM) of 185.7 dBc/Hz at 18.5 GHz, with 0.0875 mm² (250 µm × 350 µm) area.