On Sunday, October 25, 2015 11:56:13 PM Gerhard Hoffmann wrote: > Am 24.10.2015 um 22:21 schrieb Bruce Griffiths: > > On Saturday, October 24, 2015 09:03:21 AM Charles Steinmetz wrote: > >> The spec sheet says both TimePod inputs accept -5 to +20dBm into 50 > >> ohms. -5dBm is less than 0.4Vp-p, which requires less than +/-4mA > >> from the source, so a 0-5v comparator output feeding a > >> capacitor and a 560 ohm series resistor should work fine as long as > >> the comparator can source and sink at least 4mA. > > > > The fly in the ointment is that with such low level inputs (the LTC6957-4 > > evaluation board will deliver +4dBm into 50 ohm) the Timepod phase noise > > floor is uncomfortably close to the phase noise floor of the LTC6957. > > > >> Alternatively, a 0-5v comparator output could be buffered with three > >> 'AC04 inverters in parallel, or an 'AC line driver -- but that adds s > >> the PN of the gates. > > > > Not if one uses a pair of drivers one to drive the Timepod Ch0 input and > > one to drive the Timepod CH2 input. > > > > It would perhaps be useful to measure the PN characteristics of several > > comparators and other sine to square converter circuits using a Timepod > > or equivalent. > > For the sake of repeatability, could we agree on a common setup? > Timepod would be ok for me. Levels, sources, filters, splitters... > > regards, Gerhard > > > _______________________________________________ > 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. Gerhard I'll start another thread on this initially detailing how I measured the PN of the LT6957-4. Bruce