[time-nuts] 1Mhz to 1 PPS
Mike Fahmie
mpfahmie at lbl.gov
Fri Nov 30 00:36:15 UTC 2007
At 06:02 AM 11/27/2007, you wrote:
>You will need a clock shaper to convert the sine to a digital signal, and
>a series of dividers.
>
>You can look at my page on clock shapers for ideas:
>
>http://www.ko4bb.com/Timing/ClockShaper.html
>
>If you look through the archives, I believe earlier this year there was a
>thread about the respective noise performance of various logic
>technologies, but I am sure someone can recommend the current
>best-in-class divider for low noise. For any but the most demanding
>applications, I am sure that standard CMOS decade counters in the AC, HC,
>ACT or HCT series would work fine, such as the 74ACT162.
While designing a timing distribution system at a cyclotron facility that
required stability and low jitter (in the low picoseconds), I found that
thermal changes caused the logic thresholds to vary which caused the edges
to drift dozens of picoseconds. The solution was, whenever possible, to use
differential logic signals. I was using the ECLips ECL logic family so that
was an easy fix. Resync'ing to the input clock should be done as required
and again close to the output.
-Mike-
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