[time-nuts] REF osc distribution.

[Michael Tharp]

On 09/05/2012 12:46 PM, Bob Camp wrote:
> Hi
>
> There are a number of discrete transistor buffers that have very good
> isolation and short term stability / phase noise performance. I'd take a
> look at the one from the NIST papers and Bruce's more modern re-design.  All
> are in the archives. http://tf.boulder.nist.gov/general/pdf/498.pdf is a
> pretty good place to start.
>
> Mostly what they do is to run a common emitter amplifier followed by several
> common base amplifiers. They may or may not follow that with a buffer. Each
> channel gets a separate string of amplifiers. All the common emitter amps
> are driven in parallel by the reference source.
>
> The transistors used are normally cheap stuff like the 2N3904. Except for
> the power supply nothing in the circuit costs much. None of it is hard to
> find.

For an integrated (op-amp) solution, how does OPA830 stack up? I'm 
trying one out for a GPSDO design to buffer the signal from the OCXO for 
50 ohm output, but I may also build a distribution amplifier at some point.

At $1.91 for single pieces on Digi-Key it's not terribly expensive, but 
something cheaper could probably get the job done. There are also dual 
and quad versions (OPA2830 and OPA4830).

-- m. tharp