A 30-MHz, 90-ppm/°C fully-integrated clock reference generator with frequency-locked loop

A temperature- and supply-independent clock generator has been developed using 0.35-µm CMOS technology. This generator is based on a simple frequency-locked loop technique and can be implemented monolithically without using LC resonant circuits, quartz resonators, and MEMS oscillators. A sample device that is tunable over a wide frequency range of 2–100 MHz was designed and fabricated. It showed a temperature coefficient of 90 ppm/°C, a line regulation of 4%/V, and a power dissipation of 180 µW, at a frequency of 30 MHz. The process sensitivity (σ/μ) was 2.7%. This clock generator can be used as an on-chip reference clock circuit.