A PVT-tolerant relaxation oscillator in 65nm CMOS

A fully-integrated CMOS relaxation oscillator (ROSC) using a process-voltage-temperature (PVT) insensitive current reference generator is presented. The oscillator is designed to generate a clock frequency of 64.4kHz in 65-nm CMOS technology for switched-capacitor circuit applications. The Monte-Carlo simulation results have shown that the ROSC is able to achieve 3.66% in the process sensitivity (σ/μ). The output frequency variation is 1.71% over the temperature range from -20°C to 100°C and 0.73% over the supply variation from 1.2V to 2V. The power consumption of ROSC is 4.32μW at 1.2V supply. It has displayed better figure-of merit (FOM) against PVT variations with respect to other reported prior-art works.