[time-nuts] 10 MHz -> 16 MHz

jimlux jimlux at earthlink.net
Sun Sep 30 10:54:41 EDT 2018


On 9/29/18 8:57 PM, Tom Van Baak 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
> 
> 

cycle counts over what interval?  5 and 8 cycles respectively? or over, 
say,  1 second?

Multiply by 8 divide by 5 seems a bit tricky (although any number of off 
the shelf DDS will do it at fairly high power dissipation)

You might be able to injection lock an 80MHz oscillator by coupling the 
10 MHz in on the Vcc or output.

Then a divide by 5 down to 16.

If the requirement is over 1 second, then you can play a game with 
counting the first half of the second, and adjusting in the second by 
dropping/adding cycles to make it come out right. THat sounds pretty icky.




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