A Low Phase Noise 11.8-15.3 GHz CMOS LC-VCO with High-Q Inductor

Abstract

This work presents a 14GHz LC voltage controlled oscillator (VCO) by using high quality (Q) factor inductors. The LC-VCO consists of a NMOS cross-coupled pair and differential buffer for test purposes. To increase the VCO phase noise performance, double-turn parallel single-width inductor is used to achieve high tank quality factor. With 5-bit control bits, the VCO has a wide frequency tuning range (FTR) of 25.9 % (i.e. from 11.8 GHz to 15.3 GHz). At 14.64 GHz, the measured phase noise is -136.57 dBc/Hz @ 10 MHz offset frequency, which corresponds to a Figure of merit (FoM) of -188.25 dBc/Hz. Fabricated in a 65 nm CMOS process, the core VCO has an area of $210 \mu m \times 360 \mu m$.