So what do big name simulation front ends do when probing current, does the simulator modify the netlist by sticking in a bunch of 0V voltage sources? It would be good to know the proper method since im currently in the middle of writing a front in for ngspice/gnucap to replace gspiceui.
On Fri, Apr 10, 2009 at 1:15 PM, John Doty <[email protected]> wrote: > > On Apr 10, 2009, at 1:07 PM, Yamazaki R2 wrote: > >> Sorry to randomly jump in here, but in ngspice, the only way to probe >> current is to probe a 0V voltage source? Theres no other work arounds >> for this? > > It's classic SPICE technique. > >> For example, if I had a very large hierachical design with >> 10,000 transistors in it and I wanted to plot the drain current of one >> particular transistor, I'd have to either edit the schematics and >> break apart the net and insert a 0V voltage source or hack the >> netlist? > > Hardly difficult. The most important thing any professional needs to > learn is not to get stuck on a trivial impediment. > >> Isnt that a pretty important missing feautre? Gnucap lets you >> probe device currents without hacking the schematics. > > Gnucap is a rapidly advancing work in progress. SPICE is > conservative, stagnant, but still much more important. There's > enormous knowledge and experience available for SPICE, little for > gnucap. I expect gnucap will eventually surpass SPICE in all areas, > but it isn't there yet. > >> >> On Fri, Apr 10, 2009 at 11:33 AM, John Doty <[email protected]> wrote: >>> >>> On Apr 10, 2009, at 12:19 PM, [email protected] wrote: >>> >>>> So spice won't actually calculate the current for me? >>> >>> In this particular case, you can also use Ohm's law to convert >>> voltage to current through the resistors, and KCL to get the reactive >>> currents versus time from your transient simulation. Of course, you >>> could also just do it entirely by hand from the complex impedances at >>> a given frequency. Spice is a little excessive here. >>> >>> Lots of ways to do this problem. You want to get good at this? Master >>> them all.. >>> >>> John Doty Noqsi Aerospace, Ltd. >>> http://www.noqsi.com/ >>> [email protected] >>> >>> >>> >>> >>> _______________________________________________ >>> geda-user mailing list >>> [email protected] >>> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user >>> >> >> >> _______________________________________________ >> geda-user mailing list >> [email protected] >> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user >> > > John Doty Noqsi Aerospace, Ltd. > http://www.noqsi.com/ > [email protected] > > > > > _______________________________________________ > geda-user mailing list > [email protected] > http://www.seul.org/cgi-bin/mailman/listinfo/geda-user > _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
