Low-power Scaling-friendly Ring Oscillator based ΔΣ ADC

Ring oscillators (ROs) are increasingly being used for ΔΣ ADC. This is because of the highly digital nature of ROs which makes them very amenable for design in scaled CMOS technologies. This work presents recent advances in RO based ΔΣ ADCs. In addition to being low power and scaling friendly, ring oscillators also possess intrinsic integration and quantization properties, which make them well suited for oversampling ADC applications. This work presents a review on both discrete-time and continuous-time ring oscillator based delta-sigma ADCs, as well as a novel second-order phase-locked loop (PLL)-like ring oscillator based ΔΣ ADC.