The simplest way to drop the output impedance without adding much circuitry is to just change the series R to 100 ohms or so - that would still give pretty good isolation from capacitive loading. If the R is dropped to zero, the DC performance will be best, but you'll have to worry about the amount of capacitive loading. If the lines are short - say a couple of meters or less of open wire, it would probably be OK, but that much coaxial cable may make it oscillate. The suggestion to get the feedback right from the output terminal,or even with external sensing at the load would be best for DC accuracy, but would have the same problems as above. You can also take the DC feedback from the output directly, and the AC feedback from the amplifier output, while the series resistor isolates the two. This would give good DC accuracy and AC stability, but would alter the dynamic response and LF noise shape somewhat. If you add an amplifier, you'll of course have to consider its offset and noise contribution, and it will have the same stability issues to resolve. Ed

Hi Ed, I am a little confused with regard to your paragraphs 3 & 4. Could you elaborate on those two paragraphs ? thank you, Bill....WB6BNQ ed breya wrote: > The simplest way to drop the output impedance without adding much > circuitry is to just change the series R to 100 ohms or so - that > would still give pretty good isolation from capacitive loading. > > If the R is dropped to zero, the DC performance will be best, but > you'll have to worry about the amount of capacitive loading. If the > lines are short - say a couple of meters or less of open wire, it > would probably be OK, but that much coaxial cable may make it oscillate. > > The suggestion to get the feedback right from the output terminal,or > even with external sensing at the load would be best for DC accuracy, > but would have the same problems as above. > > You can also take the DC feedback from the output directly, and the > AC feedback from the amplifier output, while the series resistor > isolates the two. This would give good DC accuracy and AC stability, > but would alter the dynamic response and LF noise shape somewhat. > > If you add an amplifier, you'll of course have to consider its offset > and noise contribution, and it will have the same stability issues to resolve. > > Ed > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.