[time-nuts] Low pn integrated frequency multiplier/PLL

[Attila Kinali]

Ciao Luciano,

On Tue, 13 Aug 2019 20:18:58 +0200
"timeok at timeok.it" <timeok at timeok.it> wrote:

>  I was wondering, and I do it to you too, if this Texas Instruments  device could be used to build a
>    frequency difference meter with high precision features.
> 
>    http://www.ti.com/lit/ds/symlink/lmx2594.pdf
> 
>    http://www.ti.com/lit/ug/tidud10a/tidud10a.pdf

If you mean by using two synthesizers to multiply DUT frequency up
and then use some technique there to get better precision. 
Then the answer is a clear maybe! 

Multiplying up will reduce your SNR proportional to the multiplication
ratio. Thus, if you have an instrument that operates already close to
the noise limit at the DUT frequency, you will not get better by 
up-multiplication. On the other hand, if all you have is a crude frequency
counter, then up-multiplication will help. But that's only because the
instrument is not the right tool for the task. With this approach, you
will still not get down to the level that a good instrument by its own can do.


			Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neal Stephenson