The 74S140 (dual 4-input NAND) is the classic TI TTL 50-ohm driver. They're still available in DIP & SOIC.
I'm currently waiting on some boards to arrive so I can try SN74LVC1G17 as a more modern replacement that's much cheaper and smaller. Once I've proven it I'll do a separate thread to the list about the whole project, since it's on-topic. On 18/3/19 1:27 pm, Bob kb8tq wrote: > Hi > > CMOS is good. The faster the better. Go to your favorite vendor and find > whatever is “king” this month > and that’s what you go with. HC has been around a *long* time and is about as > slow as it gets in terms > of 5V CMOS ( yes, 4000 series is slower still …). Faster means less delay in > the gate (so lower variation > in delay). It also turns out that faster means lower phase noise so lower > jitter. > > Buffers are better than inverters, simply because they have higher output > drive capability. One “favorite” > are the x125 and x126 tri-state buffers. NC7SZ125 and NC7SZ126 are two > examples. > > If you want to drive 50 ohms, you likely will need to parallel gates in order > to handle the current. There is > an ongoing debate about source termination vs load termination vs “both > termination” vs “don’t bother”. > I would suggest that terminating one end or the other is a … errr …. really > good idea. > > Lots more information in the archives. > > Bob > >> On Mar 17, 2019, at 6:39 PM, Taka Kamiya via time-nuts >> <[email protected]> wrote: >> >> I'm very curious, too. Especially when I *just* built one using 74HC04N. >> >> --------------------------------------- >> (Mr.) Taka Kamiya >> I'm stuck in a wormhole.... Hello, worms! >> >> On Sunday, March 17, 2019, 4:01:26 PM EDT, Hal Murray >> <[email protected]> wrote: >> >> >>> For 1PPs the main goal is jitter and the selection of the ICs is very >>> tricky >> >> Could you please say more? Do you mean logic family selection, or chip >> selection within a family? >> >> Most modern digital chips are CMOS with an input threshold of VCC/2. I'd >> expect power supply noise to be important and families with faster switching >> times probably make more noise. >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
