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 <[email protected]> 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 -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
