A 51.3-MHz 21.8-ppm/°C CMOS Relaxation Oscillator With Temperature Compensation

A 51.3-MHz 18-mu W 21.8-ppm/degrees C relaxation oscillator is presented in 90-nm CMOS. The proposed oscillator employs an integrated error feedback and composite resistors to minimize its sensitivity to temperature variations. For a temperature range from -20 degrees C to 100 degrees C, the fabricated circuit demonstrates a frequency variation less than +/- 0.13%, leading to an average frequency drift of 21.8 ppm/degrees C. As the supply voltage changes from 0.8 to 1.2 V, the frequency variation is +/- 0.53%. The measured rms jitter and phase noise at 1-MHz offset are 89.27 ps and -83.29 dBc/Hz, respectively.