Hi Magnus, The C channel is the SMA on the back of the PCB. The input of 74LVC2G14 is set to 0.5vcc with 1k resistor and AC coupled with 100nF. Today I compared the performance 74LVC2G04, 74LVC2G17, 74LVC2G14. http://www.qsl.net/b/bi7lnq//freqcntv4.1/test/20150224/ . I saw people talking about using 74AC to square the signal, what's the difference between 74LVC and 74AC? 74AC is not easy to get.
Thanks Li Ang 2015-02-24 5:36 GMT+08:00 Magnus Danielson <mag...@rubidium.dyndns.org>: > Dear Li Ang, > > Nice to have you back reporting on your progress! > > Now, you have some pretty impressive performance going on there. Looks > like a nice little unit too. > > Is the C-channel the SMA on the back of the PCB? > > How did you wire up the 74LVC2G14? > > While it is tempting to use both channels in it, don't if you want to keep > cross-talk between channels low. > > Cheers, > Magnus > > > On 02/23/2015 02:10 PM, Li Ang wrote: > >> Hi, >> I'm back. I have been testing my new borad for days. >> Compared to previous version, this board makes the PCB track of >> signals far from each other and replaces LDO for TDC with LP5907. >> CH_A: simple resistor bias and ac couple "front end", CH_B: >> CH_A+MC100LVELT22 LVPECL , CH_C: CH_A+74LVC2G14 . >> At first, the result is worse than previous board. Using CH_B as the >> REF and DUT source, the stdev of the phase measurement is about 160ps. The >> old board can reach about 70ps. CH_A and CH_C are way much better than >> CH_B. That bothers me for days. >> Today, I use the 74LVC2G14 to square the signal from MV89A, and do >> the same test. For all three channel, the stdevs are about 37ps. The spec >> of TDC_GP22 is 35ps. And now the performance looks a little bit better than >> the previous board. It looks like that the jitter of MC100LVELT22 is much >> bigger at slow slew rate. >> It seems that next step is to play with the front end. >> >> >> The raw data is uploaded to http://www.qsl.net/b/bi7lnq/ >> freqcntv4.1/test/20150222/ >> The pic of this version is uploaded to http://www.qsl.net/b/bi7lnq/ >> freqcntv4.1/pic/ >> >> >> >> >> Regards >> Li Ang >> >> >> >> _______________________________________________ >> 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.