[time-nuts] fast switching quiet synthesizer

Jim Lux jimlux at earthlink.net
Tue Oct 7 19:36:42 EDT 2014


On 10/7/14, 10:32 AM, Magnus Danielson wrote:
> You should be able to use DDS test-boards and by timing your last write,
> you should be able to time the frequency jump.
>
> The STEL-1173 takes 6 bytes, but writing the last one latches all 6
> bytes over to a single 48 bit word. I expect that other DDSes have the
> same distinct transfer-phase if you only look in the datasheet for the
> details.
>

Yes, virtually all of them have a "load" input of some form (I'm 
familiar with the AD98xx and AD99xx ones, and they certainly do).

What I'd really like, though is something at a slightly higher level of 
integration (for which I am willing to pay.. it's a time vs money 
thing).  Does someone sell a DDS in a box with connectors, etc.

I need a tuning range, for now, of around 3.1 to 3.4 GHz, so any of the 
"1 GHz" DDSes can generate something that I could mix up with a 2.8-3 
GHz LO (which I have), although I'd have to be careful about images.
Or I can run the few hundred MHz out of the DDS into a doubler/tripler, 
then mix up.



> Some of the modern DDSes can take 10 MHz directly and step it up
> internally before hitting the DDS core, but it may be that you need to
> synthesize a higher clock from the 10 MHz first.
Not a problem, I think I have a 10 in to 100 MHz out set of bricks from 
Wenzel (x5 and x2) from a previous project





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