I think one should recall that for very deep phase-noise numbers for far-out noise, we cannot remove the suspicion of cross-correlation cancellation problems have overstated the phase-noise levels. I've seen both instrument makers and oscillator makes handwaving to protect the values which so far is understood to be non-physical.
Cheers, Magnus On 2020-01-10 03:25, Bruce Griffiths wrote: > That's not possible at room temperature since thermal noise will limit the > residual PN to -180DbC/Hz with a noiseless amplifier and a +3dBm input. > > Bruce > >> On 10 January 2020 at 14:38 Lifespeed <lifesp...@claybuccellato.com> wrote: >> >> >> Hi Time Nuts, >> >> >> >> I have a need for a low phase noise, noise floor and noise figure amplifier >> at 400MHz. I have tried some off-the-shelf 50 ohm amplifiers, the best of >> which degrades phase noise by a couple dB. I'm working with a signal with >> -172dBc/Hz PN, so not much tolerance for degradation here. The input signal >> level is only 3dBm, so noise figure still matters as well. I'm looking for >> 15dB gain, 16dBm P1. The residual phase noise would have to be better than >> -180dBc/Hz, and I would probably operate the amplifier slightly compressed. >> >> >> >> Any suggestions on topologies, transistors, white papers, etc? I'm >> considering the NXP BFU590Q silicon bipolar transistor, which I have used in >> a transformer feedback configuration at 100MHz with less than -180dBc/Hz PN. >> But this topology doesn't appear practical for 400MHz due to the difficulty >> maintaining a high collector impedance at that frequency with a transformer. >> Nor do I need to control the gain, which is one of the features of the >> transformer-feedback topology. I was thinking about common emitter with >> inductive emitter degeneration. Not sure cascode is right for this UHF >> application. >> >> >> >> Lifespeed >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.