Negative time
> The source starts at the threshold voltage of 5 due
> to the delay of -2n, then it goes up to 10, then falls to 0.
> The switch should start in the on position and stay on until
> the source
> voltage falls below 4v. However, with my old spice code, the output
> oscillates at the onset of the transient.
>
> VCS_Test.ckt
> V1 77 0 DC 12.5
> R1 4 0 1K
> S1 77 3 33 0 S2_switch on
> V2 33 0 DC 5 PULSE( 0 10 -2n 4n 4n 2n 10n)
> R2 33 0 1K
> VAm1 3 4 0
> IVm1 33 0 0
> .model S2_switch SW vt = 5 vh = 1 ron = 1 roff = 1gig
> .OPTIONS gmin = 1E-12 reltol = 1E-4 itl1 = 500 itl4 = 500
> .TRAN 1u 10n 0 .5n uic
> .IC V(33)= 5
> .END
Wow ! I'd never have expected spice to handle things
which "happened" before the simulation started. But I
suppose there's no reason why it shouldn't handle these
simple things, if it can be implemented simply.
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