Swing and Phase-Noise Enhanced VCO With Capacitive-Division Dynamic-Threshold MOS

Abstract

This letter presents a swing and phase-noise enhanced dynamic-threshold voltage controlled oscillator (VCO) using a capacitive division technique. This technique prevents forward biasing of the pn-junction between the body and source when the output swing increases, which results in low phase noise. The proposed VCO shows phase noise of $-$ 122.0 dBc/Hz at a 1 MHz offset frequency at 2.31 GHz and a figure of merit of $-$ 192.7 dBc/Hz while consuming 0.46 mW from a 0.38-V supply voltage. It is implemented using a 0.11 $\mu\text{m}$ CMOS process with a chip area of 0.96 $\text{mm}^{2}$ .