A 46 mu W, 8.2MHz Self-threshold-tracking Differential Relaxation Oscillator with 7.66psrms Period Jitter and 1.56ppm Allan Deviation Floor

Abstract

This paper presents an 8.2MHz relaxation oscillator with swing boosting and self threshold tracking, designed to improve both period jitter and frequency stability. A self-threshold-tracking loop ensures the switching threshold is kept in a constant, reducing the frequency uncertainty from process, temperature and supply voltage variations. Implemented in a 180nm CMOS process, the design achieves a period jitter of 7.66psrms, an Allan deviation floor of 1.56ppm, a temperature coefficient of 123ppm from-20 to 100 degrees C, and an FOM of 160.9dBc/Hz while only consuming 46.3 mu W. The power efficiency of the design is 5.6kHz/nW.