A broadband CMOS LC voltage-controlled oscillator for FMCW synthesizer

A broadband CMOS LC voltage controlled oscillator (VCO) for an FMCW synthesizer application was developed, which achieves wide tuning range and low phase noise. The VCO employs a topology of NMOS cross-coupled pair and NMOS tail current source. In order to lower phase noise while fulfill continuous tuning range of 2GHz, P-type AMOS varactors are used, which connect to LC tank through a MIM coupling capacitor. This VCO is implemented in a 65 nm CMOS RF technology. Post-layout simulation shows that, consuming 17.4mW under a 1.2 V supply, the proposed VCO can be tuned from 14.09 to 16.28 GHz and exhibits phase noise of -109dBc/Hz at 1 MHz offset from the 14.4 GHz carrier. VCO figure-of-merit (FoM) of -180.2dBc/Hz and FoM_T of -183.4dBc/Hz are achieved.