The amount of jitter verses logic family is all over the place as well. Take a look at an LS verses an HCT vs an S family and you will see what I mean. Some of them are very nasty, and are not all created equally.
Jerry At 09:58 AM 8/22/2012, you wrote: >I was not measuring cycle to cycle jitter but the input to output >jitter of a TTL gate itself when used as part of a delay circuit. The >input circuit and input waveform to the gate are very similar to what >would be expected in a sine wave zero crossing detector. > >Using a 7S11/7T11 in sequential sampling mode, I could see the jitter >fine on any analog 7000 series oscilloscope but to get a nicer photo, >I used a 7834 in variable persistence mode. The trigger occurs about >80ns before the displayed fast rise pulse. Most of the jitter is a >product of the low power supply rejection of the TTL gate and input >circuit. > >http://www.banishedsouls.org/c2df3757f1/PG506/PDJ%20Test%201b%20-%201.jpg > >Using hard limiting before the zero crossing detector will relax the >design of the later significantly. Differential signal paths would >help considerably as well. > > From going through the manuals and specifications, I am just not sure >the TDS220 or TDS3012 has the time base resolution necessary to >compare the jitter from the two different designs. On my 2440, it was >very difficult to see any difference between no jitter and the jitter >in the example I linked above. > >On Wed, 22 Aug 2012 15:44:10 +0200, Azelio Boriani ><[email protected]> wrote: > >>According to >> >>http://cp.literature.agilent.com/litweb/pdf/5989-8794EN.pdf >> >>the real time sampling scope (like the TDS220 or TDS3012) can measure cycle >>to cycle jitter directly, whereas the equivalent time sampling has only one >>sample each trigger and a little delay on the sampling point for the next >>trigger. The displayed waveform is a sort of "sum" of more than one cycle >>and now I can't figure out what type of picture this can give. The TDS3012 >>has also the advantage of the Digital Phosphor behavior that can be useful >>for the jitter analysis. Maybe a stable timebase and low jitter external >>trigger input are essential. Unfortunately the TDS3012 has a 200ppm >>timebase... >> >>On Wed, Aug 22, 2012 at 2:54 PM, David <[email protected]> wrote: >> >>> Do you mean with a 7404 hex inverter? I actually did something like >>> this recently while adding a 75ns pre-trigger pulse to an existing >>> fast rise pulse generator. >>> >>> The pre-trigger pulse ended up having significant pattern dependant >>> jitter caused by the adjacent TTL divider chain modulating the supply >>> voltage and the poor power supply rejection of the 7404. I was easily >>> able to see the jitter on my 7T11 sampling oscilloscope but on my 2440 >>> (20 GS/sec equivalent time sampling), it was barely perceptible if >>> that despite ideal conditions. The peak to peak jitter was about >>> 100ps. >>> >>> As far as I could tell from the available online documentation, the >>> TDS220 and TDS3012 have relatively low sample rates and do not support >>> equivalent time sampling so I would expect them to show even less than >>> my 2440. >>> >>> On Wed, 22 Aug 2012 11:55:11 +0200, Azelio Boriani >>> <[email protected]> wrote: >>> >>> >In your opinion, if I build a 7404 ZCD and a hard limiter one, can I see >>> >the jitter difference on a simple 'scope (Tek TDS220 or TDS3012) or do I >>> >need the Wavecrest SIA3000? >>> > >>> >On Wed, Aug 22, 2012 at 1:37 AM, Bob Camp <[email protected]> wrote: >>> > >>> >> Hi >>> >> >>> >> Since the Collins approach "tunes" the system for a single frequency >>> input >>> >> (more or less), the approach is probably not the best for a "many >>> decades" >>> >> sort of frequency range. There are a number of things that he alludes >>> to in >>> >> the paper, but does not directly address. The most obvious is the >>> >> temperature dependance of the "stuff" the system is made of. Another is >>> the >>> >> simple fact that a non-clipping linear amplifier is likely the best >>> choice >>> >> for a first stage, provide the input is not already near clipping. >>> >> >>> >> Bob >>> >> >>> >> On Aug 21, 2012, at 12:50 PM, [email protected] wrote: >>> >> >>> >> > Hello everyone, >>> >> > >>> >> > I am new to this forum. >>> >> > It looks like a lively discussion on various topics. >>> >> > >>> >> > A colleague of mine here at Agilent pointed me to this paper entitled >>> >> "The Design of Low Jitter Hard Limiters" by Oliver Collins. In Bruce >>> >> Griffiths' precision time in frequency webpage, this paper is described >>> as >>> >> "seminal." >>> >> > (http://www.ko4bb.com/~bruce/ZeroCrossingDetectors.html) >>> >> > >>> >> > Since I'm trying to create a limiter that will accept frequencies >>> >> ranging from 1 MHz to 100 MHz, I thought it would be good to understand >>> the >>> >> conclusions of this paper (if not the mathematics as well). The >>> >> mathematics turned out to be quite challenging to decode. Has someone on >>> >> this forum unraveled the equations? It appears Collins has >>> recommendations >>> >> on the bandwidth and gain of a jitter minimizing limiter, and then >>> extends >>> >> this analysis to provide the bandwidth and gain of a cascade of >>> limiters. >>> >> But the application is still fuzzy. In figure 5, he shows a graph >>> showing >>> >> the dependence of jitter on crossing time. Is the crossing time >>> (implied >>> >> by equations 7) considered a design parameter one can vary? Also, on >>> figure >>> >> 4, the "k" parameter has been varied to show the rising waveform as a >>> >> function of "k". The threshold is always assumed to be 0.5. So could >>> "k" >>> >> be related to "tau", the time constant of the RC filter? >>> >> > >>> >> > Thanks in advance for all your help. >>> >> > >>> >> > Yours >>> >> > >>> >> > Raj >>> >> > >>> >> > >>> >> > >>> >> > _______________________________________________ >>> >> > time-nuts mailing list -- [email protected] >>> >> > To unsubscribe, go to >>> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >> > and follow the instructions there. >>> >> >>> >> >>> >> _______________________________________________ >>> >> time-nuts mailing list -- [email protected] >>> >> To unsubscribe, go to >>> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >> and follow the instructions there. >>> >> >>> >_______________________________________________ >>> >time-nuts mailing list -- [email protected] >>> >To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >and follow the instructions there. >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>_______________________________________________ >>time-nuts mailing list -- [email protected] >>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>and follow the instructions there. > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. Jerry Mulchin _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
