[time-nuts] 10 MHz -> 16 MHz

Ben Bradley ben.pi.bradley at gmail.com
Sun Sep 30 15:20:37 EDT 2018


There's this clock chip that might do it all-in-one. it has a built-in
PLL and several internal dividers for generating clock signals at a
wide range of frequencies. Adafruit has a breakout board for it.
Unfortunately, some people are calling it a DDS even though it's not:
https://www.mouser.com/new/Silicon-Laboratories/silabssi5351/

How about (my original thought, but the above chip may be perfect for
the job) two doublers to generate 40MHz to drive a DDS set to generate
16MHz? This won't EXACTLY be perfect cycle count as 16/40 (or 2/5)
can't be exactly represented in binary, but I calculate that a 32 bit
approximation would lose 1 cycle about every couple of minutes. The
good part is you can calculate exactly how many cycles off you'll be
based on how long it's been running.
On Sat, Sep 29, 2018 at 11:58 PM Tom Van Baak <tvb at leapsecond.com> wrote:
>
> What's a clever, simple, reliable (pick 2 of 3) way to get 16 MHz out of 10 MHz? Low phase noise isn't a big requirement and jitter doesn't need to be sub-nanosecond. The main requirement is perfect cycle count accuracy. This is for driving a 16 MHz microcontroller from a 10 MHz Rb/Cs/GPSDO. 10 MHz input is likely sine; 16 MHz output is 3v3 or 5v CMOS.
>
> Thanks,
> /tvb
>
>
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