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.