[time-nuts] what is the best way to multiply a 10 Mhz signal?

Chris Albertson albertson.chris at gmail.com
Tue Dec 21 18:27:50 UTC 2010


This might explain a way to do it
http://physics.eou.edu/courses/phys345/lab14_pll.pdf

What this is doing is simple.  It is a 70Mhz voltage controlled oscillator
who's frequency is controlled such that every 7th cycle the phase matches
your 10MHz reference.  The example above does divide by 10 or 128 but
7 is the same thing.

The way to make a divide by 7 is to have a counter feed a comparator and
on match the comparator resets the counter.  The reset signal is your output.
It requires two 50 cent chips

Can you use 80Mhz or 100Mhz.  Either of these is easier and uses one less
chip.


On Tue, Dec 21, 2010 at 9:57 AM, Stephen Farthing <squirrox at gmail.com> wrote:
> Hi Rich....
>
> Thanks for the reply....I have an AD9834 DDS chip I want to use for a
> Frequency generator with an accuracy of 1 Hz from 0-30 Mhz. . This part can
> be clocked at 75 Mhz - but unlike other DDS chips seems to have no internal
> clock multipliers. So it seems to me if I can some how generate a 70 Mhz
> clock signal from my rubidium standard I can solve the problem.
>
> 73s Steve
>
> On 21 December 2010 17:36, Richard (Rick) Karlquist
> <richard at karlquist.com>wrote:
>
>> I used to be in the synthesizer business (Zeta Labs)
>> in a previous life.  I learned to ask the customers:
>> what you are trying to accomplish as the end goal,
>> before tackling a messy problem like multiplying by
>> 7.  Maybe you don't need to multiply by 7, but we
>> can't tell from your question.
>>
>> Rick Karlquist N6RK
>>
>>
>> On 12/21/2010 8:35 AM, Stephen Farthing wrote:
>>
>>> Hi everyone,
>>>
>>> I want to multiply the output from my Efratom 101 (10Mhz) to clock a DDS
>>> at
>>> 70 Mhz. Has anyone tried this?
>>>
>>> Regards,
>>>
>>> Steve G0XAR
>>>
>>>
>
>
> --
> It is vain to do with more that which can be done with less.
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-- 
=====
Chris Albertson
Redondo Beach, California



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