> From: "Bob Camp" <[email protected]>
> Subject: Re: [time-nuts] Realistic Tbolt phase noise
> Hi
> I think you will find that the noise floor of the ADF4107 (dividers and
> phase detector) is a bit higher than -150 at 100 Hz offset at 10 MHz. It
> should get you past the -120 level though. That's still much better than you
> are seeing.
> Indeed -120 is not what figure 15 on page 8 of the specification would
> imply. I'm sure that the figure is technically correct. It's just not
> showing the complete picture.
> Bob
I have found the Analog Devices chips to have a very poor phase comparator
noise floor close-in. If you do the math based on their published figure of
merit, it won't add up.
I believe the issue is 1/F noise due to the low-current CMOS process they use.
They are cheap, jelly-bean chips that have their uses. Definitely not high
performance. Bipolar is they way to go.
Clay
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