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: li...@rtty.us > Date: Wed, 5 Sep 2012 17:37:34 -0400 > To: time-nuts@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 <g...@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 > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
