hello all I m testing an analog circuit time based which inc

Question

hello all I m testing an analog circuit time based which includes a d flip flop and I would like to replace it by an ideal d flip flop to decouple some issues is there some way to do this I found the d dff digital model on the ngspice is there any way to 1 integrate that component in an xschem testbench using a symbol how do i do the model and the link to a symbol 2 integrate it with analog signals using dac bridge and adc bridge or any other ideas would be really helpful

Tim Edwards · Answer

Yes that s the right approach Possibly the quickest way to get there is to use the `spi2xspice py` script in `qflow` which will convert a SPICE netlist using standard cells into its xspice equivalent subcircuit

Tim Edwards · Answer

But just to implement a single flip flop in xspice you d want something like this unverified ``` subckt myflop a vdd a gnd a in a clk a out model todig 3v3 adc bridge in high=2 2 in low=1 1 + rise delay=10n fall delay=10n model toana 3v3 dac bridge out high=3 3 out low=0 model ddflop d dff ic=0 rise delay=1n fall delay=1n AA2D1 a gnd d gnd todig 3v3 AA2D2 a in d in todig 3v3 AA2D3 a clk d clk todig 3v3 A1 d in d clk d gnd d gnd d out NULL ddflop AD2A1 d out a out toana 3v3 ends```

Jorge Marin · Answer

Thanks a lot for confirming < U016EM8L91B> I m trying but no success for now I still need to find out how to connect this with the xschem symbols I ll better ask in < C017P3RAD42|xschem>

Jorge Marin · Answer

ah ok found an explanation by < U01819B63HP> here

Stefan Schippers · Answer

< U0285R77C4W> < U016EM8L91B> i have wrapped Tim s model into a `ngspice flop sym` as you can see it works The overall delay is a bit too high so the A D D A conversion delays must be lowered somewhat in the model The new components are available on

Jorge Marin · Answer

Hello < U01819B63HP> WOW that s great A more basic question how do i update to get this locally without messing up any dependencies Just doing the make step again

Jorge Marin · Answer

Thanks so much by the way

Stefan Schippers · Answer

< U0285R77C4W> If you rebuild open pdks it will fetch the updated xschem sky130 libs including the new flop However this takes lot of time cpu disk activity Just copy `ngspice flop sch ngspice flop sym test ngspice flop sch` from into your open pdks install like in ` share pdk sky130A libs tech xschem sky130 tests `

Jorge Marin · Answer

Ok thanks a lot once more < U01819B63HP>

Jorge Marin · Answer

< Alfonso Cortés> < Vicente Osorio> FYI

Jorge Marin · Answer

< aquiles viza> regarding xspice models