A self-sufficient digitally controlled ring oscillator compensated for supply voltage variation

A self-sufficient Giga-Hertz digitally controlled ring oscillator for clock distribution network is presented in this paper. It features a high supply insensitivity in order to mitigate the additional jitter due to supply noise. This is achieved by inducing a mutual compensation between the oscillation frequency parameters that are affected by the supply voltage variations. The proposed method can be easily implemented and takes advantage of the deep sub-micrometer effects peculiar to topical CMOS technologies. We demonstrate by simulations that this approach remains efficient over process variations despite the reliability issue of short channel MOS transistors.