Hi The same process issues that make for a “less than perfect” ADC, also add more than a little noise into the circuit. Exactly which component(s) are the biggest culprits … no idea. About all you can do is take data and look at the results.
Bob > On May 11, 2016, at 4:55 AM, David <davidwh...@gmail.com> wrote: > > Was that a couple of nanoseconds of resolution or minimum time > interval? > > Based on the simplified schematic which shows the current source being > controlled by a single XOR gate, it looks to me like the minimum time > interval is much longer than the achievable single shot resolution. > > On Tue, 10 May 2016 21:37:08 -0400, you wrote: > >> Hi >> >> I have not dug into them for several years. Back when I did, you were >> pushing >> their limits as a couple of nanoseconds without getting into things like >> lots of >> averaging. >> >> Bob >> >>> On May 10, 2016, at 8:29 PM, David <davidwh...@gmail.com> wrote: >>> >>> I ran a search through the time-nuts archives and found only one >>> mention of this a couple years ago asking the same question which is, >>> has anybody explored the capabilities of the Microchip PIC CTMU for >>> use as a time to digital converter or programmable delay? >>> >>> The Microchip datasheets lack detailed performance specifications but >>> my conservative estimate is that resolution down to 500ps over 200ns >>> using the built in 10 bit ADC should be possible without complex >>> calibration. (The PIC series ADCs with more than 10 bits are pretty >>> horrible.) >>> >>> See What You Can Do with the CTMU: >>> http://ww1.microchip.com/downloads/en/AppNotes/CTMU%2001375a.pdf >>> >>> Overview of Charge Time Measurement Unit (CTMU): >>> http://www.microchip.com/stellent/groups/SiteComm_sg/documents/DeviceDoc/en542792.pdf >>> >>> PIC18(L)F2X/4XK22 w/10 Bit ADC: >>> http://ww1.microchip.com/downloads/en/DeviceDoc/39977f.pdf >>> >>> PIC18F66K80 w/12 Bit ADC: >>> http://ww1.microchip.com/downloads/en/DeviceDoc/39977f.pdf >>> >>> I prefer more discrete implementations but this might be useful for >>> its higher integration, lower cost, and simplicity in less demanding >>> applications. > _______________________________________________ > 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.