Right, I'm speaking specifically of L(f). The device being driven by the oscillator doesn't care about the NF of the driver stage, only what a PN analyzer would measure at the output jack.
For any 50-ohm source, the practical L(f) floor is -177 dBm/Hz - the carrier power in dBm. No oscillator with an output of 0 dBm can be quieter than -177 dBc/Hz at any offset, but an oscillator that puts out +20 dBm could approach -197 dBc/Hz. Given a proverbial black box containing a +17 dBm oscillator that measures -195 dBc/Hz at 100 kHz, the interesting question is, "What's in the box?" There could be a passive resonator that's shaving off the broadband noise after the last active stage without contributing additive noise of its own. Another possibility might be cross-spectral collapse due to correlated thermal noise from the splitter. -- john, KE5FX Miles Design LLC > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of KA2WEU-- > - via time-nuts > Sent: Thursday, August 11, 2016 2:37 PM > To: time-nuts@febo.com > Subject: Re: [time-nuts] State of the art of crystal oscillator measurements > > NO, the maximum possible noise dynamic range is ( 177 + Pout) [dBm] - > Transistor large signal NF ( dB), > the signal to noise ration is dimensionless !!!! > _______________________________________________ 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.
