[time-nuts] Test equipment-level phase noise PLLs

[Matt Ettus]

In looking into extremely low phase noise synthesizers, I have come
across the new HMC700LP4 chip from hittite, which seems to have the
best figure of merit I have found, -227 dBm/Hz.  That gives you
-107dBc/Hz at 20 kHz offset at 6 GHz according to the datasheets.

That sounds amazingly good, but my R+S signal generator does better.
Do they use a different sort of architecture?  Do they not use
conventional dividers?  Some other sort of phase detector?

Thanks,
Matt