If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a gain of +2 The subcircuit model provided by ADI is useless for noise, unfortunately.  I guess I'll have to build and measure, which I don't mind doing.  Unless it turns out to be a waste of time, and I should have just used the transistor circuit. Clay

Clay, I would really like to have a copy of your test board for this effort. I'm sure it will be a challenging layout. But it could be a very handy piece of hardware. Supporting a PCA order would easy to do. Pete Rawson On Feb 19, 2010, at 6:17 PM, life speed wrote: > If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a gain of +2 > > The subcircuit model provided by ADI is useless for noise, unfortunately. I guess I'll have to build and measure, which I don't mind doing. Unless it turns out to be a waste of time, and I should have just used the transistor circuit. > > Clay > > > > > _______________________________________________ > 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.

life speed wrote: > If I can believe the simulation (a big if) the ADA4899-1 can provide 90 dB isolation at 10 MHz, rolling up to 70 dB at 100 MHz, when configured with a gain of +2 > > The subcircuit model provided by ADI is useless for noise, unfortunately. I guess I'll have to build and measure, which I don't mind doing. Unless it turns out to be a waste of time, and I should have just used the transistor circuit. > > Clay > > Its easy to calculate a lower bound to the amplifier phase noise floor from the signal level at the output and the amplifier output noise due to feedback resistors together with the amplifier input voltage and current noise. The actual phase noise floor may be a few dB higher. Bruce