Process-and-temperature compensated CMOS voltage-controlled oscillator for clock generators

A voltage-controlled oscillator (VCO) with a current subtraction bias (CSB) for compensating the CMOS process-and-temperature variations is proposed and analysed. The design, fabrication, and testing of a clock generator with a VCO using CSB and conventional fixed bias (FB) is reported. Measurement results demonstrate that the frequency range of CSB selection has 36% reduction against that of FB selection and the temperature coefficient of 76% reduction.