Design and Analysis of Collective Pulse Oscillators

Abstract

Collective pulse oscillators (CPOs) are novel designs constructed using pulse regenerative amplifiers that exhibit timevariant 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 ∝ −10 log p for power ∝ 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. Closedform 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.

Long-Range Pulse Interactions in Unclocked FPGAs

“…As an initial motivation for future modeling, we note that in both [20] and [24] there exists some type of pulse coupling model such that the time for a pulse going around a loop depends on the interval between it and the preceding pulse in the delay. These types of models require a mechanism for altering the time of a pulse around the feedback loop.…”

“…Interactions between pulses in feedback loops that result in PTE have been previously reported in both electronic and optical systems. Micro-pipeline rings [17], self-timed ring oscillators [18], [19], and collective pulse oscillators [20] include feedback for active jitter suppression. In these fullyelectronic systems, voltage pulses and feedback times are on similar timescales, and PTE can be achieved with a relatively short number of round trips in the feedback loops (< 50 to 500).…”

Multiwire Phase Encoding: A Signaling Strategy for High-Bandwidth, Low-Power Data Movement

“…Thus, the retimer can retrigger at minimum intervals of 20 ps, and we use a T = 30 ps in order to meet the timing constraints described in Section III. The clock used in this implementation is a 12-gate, one-pulse collective pulse oscillator (CPO) [19], designed to have a period = T min = 60 ps, and the two phases used in the link are tapped from the The driver is a single-ended make-before-break driver [20] driving a terminated transmission line of Zo ≈ 27 , with the signal swing on each line being ≈ 170 mV.…”