An Ultra-Low-Noise Swing-Boosted Differential Relaxation Oscillator in 0.18-μm CMOS

Abstract

This article presents an ultra-low-noise differential relaxation oscillator that achieves a phase noise figure of merits (FoMs) of 157.7 and 162.1 dBc/Hz, respectively, at 1- and 100-kHz frequency offsets. The oscillator is inherently robust against $1/f$ noise, while swing-boosting minimizes the phase noise arising out of thermal noise. Furthermore, an inverter-based differential comparator maximizes power efficiency, enabling FoMs close to the fundamental limits. Operating at 10.5 MHz and consuming 219.8 $\mu \text{W}$ from a 1.4-V supply, the oscillator achieves a period jitter of 9.86 psrms, equivalent to a relative jitter of 0.01%. The oscillator occupies an active area of 0.015 mm2 in a 0.18- $\mu \text{m}$ standard CMOS process.