Characterization of Noise in CMOS Ring Oscillators at Cryogenic Temperatures

Allan deviation provides a means to characterize the time-dependence of noise in oscillators and potentially identify source characteristics. Measurements on 130 nm, 7-stage ring oscillator show that declines from 300 K 150 as expected, but surprisingly increases 11 K. At low temperatures, measured can be well fit using few random telegraph (RTN) sources over range kilohertz gigahertz. Further, RTN characteristics evolve reveal an enhanced role low-frequency at lower temperatures.