[time-nuts] Sub-ps delay line
ed breya
eb at telight.com
Wed Feb 8 01:28:44 EST 2017
Even presuming this system is for clocking within a single-board
environment, that seems like a fairly tall order for setting resolution
and long-term stability. It could be tough to keep these numbers with
temperature and supply variations in all the circuitry involved,
including the parts that ultimately receive the various clock signals.
On the other hand, making it adjustable delay-wise should be fairly easy
- almost anything you do to tweak the operating conditions of this
essentially analog system will change the delays. The trick will be to
compensate for the unwanted effects, and consistently control certain
things to set the delay.
I'd recommend using differential signals throughout, if possible, with
coarse delays set by sections of on-board transmission line, and fine
adjustment by tweaking DC bias at various points. I don't think you need
to add any extra variable delays such as varicap circuits - you should
be able to affect enough control and compensation just with the normal
part characteristics.
Ed
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