[time-nuts] CPLDs for clock dividers

Gerhard Hoffmann dk4xp at arcor.de
Wed Feb 3 20:14:11 UTC 2010

paul swed wrote:
> They are indeed cheap and it would be handy to have low noise divider
> chains.
> 6 decades worth. 74ls90s get really boring to wire.
> Unfortunately I am unfamiliar with using the device. But I do seem them
> used.
> On Wed, Feb 3, 2010 at 1:59 PM, Matt Ettus <boyscout at gmail.com> wrote:
>> Does anyone have any experience using CPLDs for very low phase noise
>> dividers?  You can get an XC9536XL from Xilinx for around $1, and I
>> thought it would make a good divide by 2 through 10 device.
>> Matt
I have done that with a Virtex4-SX on a ML402 board for fun and because a customer 
insisted on it. 

It was a desaster on the spectrum analyzer. 
It will probably work if you resynchronize the CPLD output with a 74LVC1G74 to the original clock.

regards, Gerhard

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