A high‐linearity LC‐VCO with combined MOS varactors and bulk‐biased PMOS varactors for gain variation compensation

Abstract

A high‐linearity LC‐voltage‐controlled oscillator (LC‐VCO) with combined metal‐oxide semiconductor varactors and bulk‐biased P‐channel metal‐oxide semiconductor varactors in parallel is proposed to reduce the VCO‐gain (KVCO) variation and extend the linear range of the control voltage. Fabricated in a 180‐nm complementary metal‐oxide semiconductor process, the proposed topology achieves a low gain variation of less than 6.3% and a tuning range of ~28% operating from 2.31 to 3.06 GHz, corresponding to a linear control voltage range from 0.6 to 1.4 V. The phase noise is measured to be −115.3 dBc/Hz at 1 MHz offset at 3.06 GHz and the figure of merit (FoM) is −181.2 dBc/Hz. The oscillator occupies an area of 0.93 × 0.54 mm and consumes 1.8 mW from mixed 1.2/1.8 V supply voltage.