Programmable current biasing for low noise voltage controlled oscillators

In this paper a programmable highly linear voltage-to-current conversion technique for low noise, wide tunable frequency range voltage controlled oscillator (VCO) is presented. The effect of VCO gain on phase locked loop (PLL) phase noise and frequency stability characteristics is addressed. The proposed solution offers digital calibration of VCO gain and frequency, using binary weighted thick oxide MOS devices. Results of simulations in deep submicron CMOS technology are presented and discussed.