ECL has a high phase noise floor in the -140s. Other than that, it works fine.
Rick Karlquist Robert LaJeunesse wrote: > Assuming a transformer coupled input (with biasing via a secondary center > tap) > why not use a fast differential PECL to CMOS level translator? For > example, the > IDT ICS508 will take 0.3 to 1.0 V p-p input and give 2.5, 3.3, or 5 V > swing on > the output. The chip works down to DC and keeps the duty cycle in the > 40%-60% > window up to 250MHz (at 3.3V out). Jitter and noise is not spec'd however. > > > To increase the noise immunity with a relatively slow 10MHz sine source > I'd look > at boosting the amplitude with the transformer, then clipping with > balanced > series resistors and back-to-back diodes so the translator sees a higher > dV/dT > on its inputs. > > Might want to look in some old Motorola ECL appnotes for other possible > schemes. > > Bob > > > > > ________________________________ > From: jimlux <jim...@earthlink.net> > To: Discussion of precise time and frequency measurement > <time-nuts@febo.com> > Sent: Wed, December 8, 2010 10:31:08 AM > Subject: [time-nuts] reference oscillator input circuit > > I'm looking for suggestions on a general circuit that can be used to > receive an > external frequency reference (nominally a real clean sine wave at, say, 10 > MHz, > although up to 100 MHz is possible) and turn it into a "real clean" square > wave. Galvanic isolation is a plus (a transformer or capacitor would > probably > do that). > > I was thinking about rummaging through the schematics for test equipment > reference inputs (since they've already "solved" the problem, eh?), but > any > other ideas would be welcome. > > I've scanned the archives of time-nuts, and while we have a fair amount of > discussion on how to square up the 1Hz (or 100Hz) in a phase noise/ADEV > setup, > not so much on what to do with the 10 MHz. Rick has commented that you > don't > want to use a comparator. I have the papers by Dick, et al, and Collins, > as well > as all the others.. they tend to be looking at the low frequency problem, > although the analysis is certainly applicable. > > I don't know that I'm looking for the whole multiple limiting stages > scheme in > any case. > > Oh, as far as performance.. Say the need is to not horribly degrade a good > quality crystal oscillator... here's a typical set of specs: > 76 MHz > 1Hz <-90dBc > 10Hz <-110dBc > 100Hz <-120dBc > 1k-100k <-125dBc > > Adevs of the oscillator run from 5E-12 at 0.1 sec, down to 1E-12 at 10 > sec, and > back up to 2 E-12 at 1000sec. > > _______________________________________________ > 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. > _______________________________________________ > 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. > > _______________________________________________ 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.