Design and Analysis of Collective Pulse Oscillators

Collective pulse oscillators (CPOs) are novel designs constructed using pulse regenerative amplifiers that exhibit time-variant gate delay based on the residual charge from past state. This property makes it possible to achieve precise phase resolutions smaller than a pulse gate delay and/or provide identical phase taps at multiple physical locations. CPOs exhibit temporal phase error correction that results in an improvement in frequency stability \propto -10\log p for power \propto p across all timescales beyond the correction settling time. While CPOs result in device noise-based figure of merits (FoMs) comparable to that of ring oscillators, they are more resilient to power-coupled and impulse noise. This article presents a systematic time-domain analysis of the properties of CPOs based on an abstract model that captures the time-variant delay of pulse gates. Closed-form analytic solutions for CPOs disturbed by impulse noise are derived, and higher order CPOs with continuous noise injection are analyzed using behavioral simulations and characterized using Allan deviation. Hspice simulation results are presented to validate the model and compare CPOs with ring oscillators. Allan deviation and phase noise measurements on CPOs of 8 and 40 gates fabricated in GFUS8RF (130-nm) technology corroborate the theory and simulation results.