A 45 mu W, 9.5MHz Current-Reused RC Oscillator Using a Swing-Boosting Technique

Abstract

This paper presents a differential relaxation oscillator that uses swing-boost and current-reused techniques. Output swing boosting is adopted to improve noise performance, and current-reused architecture reduces the power consumption of the oscillator. Since oscillation frequency is defined by the resistor and capacitor, combining opposite temperature coefficient resistors helps eliminate temperature-caused frequency drifts. The proposed RC oscillator is fabricated using 0.18 mu m standard CMOS technology. The design achieves an FOM of 161.5 dBc/Hz with a phase noise of -108.5 dBc/Hz at 100kHz offset and an Allan deviation floor of 5.2 ppm at a 2-second integral window while consuming 45 mu W. The measured temperature coefficient is 307 ppm/degrees C in the temperature range of -20-100 degrees C, and the measured period jitter is 10.5 ps(rms).