Hello It also depends on which device primitives you can use. Xilinx spartan series has an SRL16, 16 bit shift register that can be ganged to form dividers / pre scalers. It only takes up one lut or slice, I forget which.
Link On Jun 11, 2015, at 4:11 AM, Bob Camp <kb...@n1k.org> wrote: > Hi > > Depending on which chip you are using and how big it is, you can get into the > 150 to > 500 ps range running a carry chain as a TDC.That’s without getting into > things like > hand routing and temperature / voltage issues. > > How big a chip you need will be a function of how high you can get the > internal PLL > to run while packing a bunch of stuff in the chip. If you can hit 400 MHz, > each carry > chain will need to handle a bit more than 2.5 ns, but probably less than 5 > ns. You > can do that with a carry chain a few hundred bits long. > > There is a bit of handwaving already so this is indeed a guess rather than a > design. > If you run 320 bit chains and 8 inputs, you will need 2.5K registers for the > carry chains. > You also will need about 200 registers for the support of each chain, so that > adds another > 1.6K registers. Something in the 5K register range is a possible way to go > for 8 inputs. > > Bob > >> On Jun 11, 2015, at 2:04 AM, Gregory Maxwell <gmaxw...@gmail.com> wrote: >> >> On Tue, Jun 9, 2015 at 11:40 AM, Alan Ambrose <alan.ambr...@anagram.net> >> wrote: >>> How about a 1pS resolution TIC? :) >>> >>> Or a >12 digit frequency counter? :) :) >>> >>> It's not a proper time-nut project unless there's a nutty element... >> >> Well, how complex? Front end with a fast ADC and make a DSP DMTD device? >> >> In terms of simpler things that (AFAIK) one can't go out and buy: a >> TIC with 4 or 8 inputs would be an interesting piece of time nut >> gear.even if it was 'just' 1ns resolution >> >> Surplus lab TICs are easily had but become quite a pile of equipment >> when you want to concurrently measure a half dozen oscillators. >> _______________________________________________ >> 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.