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R. Najvirt, A. Steininger:
"A Pausible Clock with Crystal Oscillator Accuracy";
Vortrag: 22nd European Conference on Circuit Theory and Design, Trondheium, Norwegen; 24.08.2015 - 26.08.2015; in: "22nd European Conference on Circuit Theory and Design", (2015), Paper-Nr. 67, 4 S.

Pausible clocking is an efficient means of establishing
communication between different timing domains without
suffering from the risk of metastable upsets, as seen with
synchronizer based solutions. On the downside, pausible clocks
are usually ring-oscillator based and hence exhibit relatively
bad accuracy and stability. In this paper we extend an existing
solution to pausible clocking that allows to synchronize the ring
oscillator to a high precision reference like a crystal clock. In that
basic solution, the generated clock will run out of sync with the
reference during a synchronization phase whenever it is paused
for longer than a clock period. Our goal here is to avoid irregular
periods of the generated clock and to keep it in sync with the
reference at all possible times. We achieve this by (a) decoupling
the communication interface in a way that allows a data transfer
without actually pausing the clock, and (b) carefully aligning the
signal timings. This finally yields a clock source that combines the
benefits of being stable like a crystal clock and allowing hazardfree
communication, like a ring-oscillator based pausible clock.