[time-nuts] Re: Oscillator for LTC6948 Ultralow Noise 0.37GHz to 6.39GHz

[John Miles]

> -----Original Message-----
> 1. Is it considered "low noise"
> 
> 2. How does it achieve low noise
> 

It's an OK part, but there are better ones out there.  Notice that you don't
get the whole 0.37 GHz-6.39 GHz tuning range from one part number.  You have
to buy the right suffix for the frequency range you're interested in.
That's not true for virtually any of its competitors.

Some of the key performance numbers are the normalized figures of merit for
PN and flicker noise.  A couple of generations ago, -226 and -274 were
great, but they are nothing special now.  ADF4377 is the best currently
(un)available, at -239 and -287.   In addition to the usual improvements in
circuits and processes, the big wins come from raising the phase detector
frequency (hence lower N factor) and adding more switchable tank circuits to
the VCO, which lowers the tuning sensitivity in any one band segment.

-- john