A 0.65-V process variation and supply noise insensitive ring VCO.

A low-voltage feedforward ring voltage-controlled oscillator (FRVCO) withstanding process variation and supply-voltage noise is proposed in this paper. In this design, the variation of transistors’ threshold voltages and supply voltage noise are detected by a compensating voltage generated circuit, and the load capacitance of the FRVCO is tuned by the compensating voltage to reduce the variation of oscillating frequency. Simulation results demonstrate that the centre oscillating frequency difference between ‘FF’ and ‘SS’ corners is reduced from 38.3% to 1.5% by tuning the voltage from 0 to 650 mV. Moreover, with a supply voltage change of ±0.5%, the frequency variation is smaller than ±0.06%. The 0.65-V 600-MHz FRVCO has been fabricated using the TSMC 130-nm CMOS process. [ABSTRACT FROM AUTHOR]