HI For quite a while, the “quick and easy” way to do it has been to run one of the Mini Circuits RPD parts into a > 5K load at audio. You get a nice big output voltage without a lot of crazy effort. Follow it with the highest voltage / lowest noise op amp you can find ….
Bob > On Dec 11, 2019, at 5:36 AM, Bruce Griffiths <bruce.griffi...@xtra.co.nz> > wrote: > > There are a number of NIST papers on this: > https://tf.nist.gov/general/publications.htm > > You can also simulate the effect of a capacitive IF port load. > However a capacitive load can also degrade the isolation and RF and LO port > mismatch. > > One can also use diode connected BJTs instead if lower close in PN is desired > at least for frequencies up to 10MHz or so. > There is a NIST paper on this as well: > https://tf.nist.gov/general/pdf/2556.pdf > > Bruce > >> On 11 December 2019 at 22:55 Tobias Pluess <tobias.plu...@xwmail.ch> wrote: >> >> >> Hi colleagues >> >> In parallel to my GPSDO project I am also thinking about a DMTD measurement >> system which should also be capable of doing phase noise measurements. This >> will be necessary to measure the stability and phase noise of my own GPSDO. >> >> There is the paper from W. J. Riley, "A small DMTD system". He uses >> TUF-R3SM+ mixers. The HP 11729C carrier noise test set uses a custom HP part >> as phase detector, and a lot of other publications I found use the HP >> 10514A, either as mixer or as phase detector. >> I wonder, which criteria are relevant to select a mixer for this application >> (besides the frequency range). Are there devices which are better when used >> as mixers, or phase detectors, or are there even devices which are good for >> both purposes? Of course, we want low noise, but for most if not all >> commercial mixers, only the isolation and conversion loss is specified, but >> I never saw a mixer datasheet having information about the mixer's noise >> contribution. So there must be other criteria people use when selecting a >> mixer for a DMTD or phase noise measurement system. >> >> Further. in this paper "OPTIMIZATION OF DUAL-MIXER TIME-DIFFERENCE >> MULTIPLIER" from Sojdr I even found a reference "The mixer output has a >> capacitive loading (22 nF) that increases the zero-crossing slope". The >> "Small DMTD system" from Riley also does have this capacitive loading. Can >> somebody explain why this does help to improve the zero crossing slope? >> >> >> Tobias >> HB9FSX >> >> _______________________________________________ >> 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.
