[time-nuts] REF osc distribution.

[Tom Knox]

I have seen that many commercial ref distribution amps are not as good as a quality low phase noise 5 or 10MHz oscillator, considering the time and resources that went into their design 
I think it would be difficult to design a amp capable of distributing something much cleaner then a LPRO.  
Thomas Knox



> From: lists at rtty.us
> Date: Wed, 5 Sep 2012 17:37:34 -0400
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] REF osc distribution.
> 
> Hi
> 
> You *can* get the job done with a CMOS inverter biased up and filtered. An op amp is likely not as good as the full bipolar approach and may be better / worse than the gate depending on exactly what you are looking at.
> 
> Bob
> 
> On Sep 5, 2012, at 12:59 PM, Michael Tharp <gxti at partiallystapled.com> wrote:
> 
> > 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
> > 
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> 
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