A 0.68–1.65GHz CMOS LC voltage-controlled oscillator with small VCO-gain and step variation

A wideband CMOS LC voltage controlled oscillator (VCO) with small VCO gain (K
_VCO
) and band step variation was developed. In order to get small K
_VCO
and step variation across different sub-bands, 8-unit capacitor array was optimized and an additional array of varactors was introduced into the LC-tank, both of which are temperature weighted. Implemented in a 65 nm CMOS RF technology, post-layout simulation shows that the proposed VCO can be tuned from 681 MHz to1656 MHz. VCO gain is around 170 MHz/V with 17% variation across the tuning range, while the step between two sub-bands is 99 MHz. Under a 1.2 V supply, the VCO exhibits phase noise of -73dBc/Hz at 10 kHz offset and phase noise -124.3 dBc/Hz at 1 MHz offset from the carrier. VCO figure-of-merit (FoM) of -184.0dBc/Hz is achieved.