[time-nuts] Close-in phase noise question...
Grant Hodgson
grant at ghengineering.co.uk
Tue Dec 16 10:05:24 UTC 2008
Brian
Could you give some more details? I think alternative solutions to
MMICs at 5 and 10MHz would give much lower phase noise.
Bruce's web pages have a number of designs that will get the 5MHz
reference up to 20MHz in 2 stages :-
http://www.ko4bb.com/~bruce/FrequencyMultipliers.html
Another approach would be to use op-amps instead of MMICs, op-amps with
a low flicker corner frequency should give lower close in noise than a
MMIC, but probably won't be as good as a discrete solution.
regards
Grant
>
>
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
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