[time-nuts] 10 MHz -> 16 MHz clock multiplier

WarrenS warrensjmail-one at yahoo.com
Thu Jan 3 05:19:16 UTC 2013


Tom

For simple, cheap, low performance and fast to build with junk box parts, 
hard to beat:
What I made long ago for myself (before time-nut days).
I still use it today for low end stuff, and it is all done with standard 
74HC DIP parts.
The main IC is a 74HCT4046 Phase lock loop with internal Osc.
The internal osc output is divided by 16  using a 74HC93. The 10MHz ref is 
divide by 10 using a 74HC90
The two 1 MHz signals are feed into it's phase comparator. A couple of 
resistors and caps and I have a low tech 16 / 8 / 4 / 2 / 1  MHz tracking 
ref.
With a couple of tweaks, I got the noise jitter down to a couple of ns as 
measured with a scope.
16 MHz is pushing the limits of the internal Osc, but I did not have any 
trouble getting there using less than the recommended osc cap.

ws

********************

"What's the simplest way to generate 16 MHz from 10 MHz? This will be for 
clocking a microcontroller at 16 MHz given 10 MHz (Cs/Rb/GPSDO).
Low price and low parts count is a goal; jitter is not a concern but 
absolute long-term phase coherence is a must.

The ICS525 (as in TAPR Clock-Block) is a good candidate but I was wondering 
if there's something cheaper, less functional, and maybe not SSOP. Any 
suggestions?

Thanks,
/tvb 




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