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pa-134a

This commit is contained in:
Meisam Bahadori 2026-07-26 12:51:58 +02:00 committed by Holger Vogt
parent 73e259bb56
commit d603b060da
1 changed files with 36 additions and 6 deletions
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42
src/spicelib/analysis/dcpss.c
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@ -1295,18 +1295,48 @@ hb_extract(CKTcircuit *ckt, const double *vsamp, int N, int P, int K,
for (i = 1; i <= N; i++)
ckt->CKTrhsOld[i] = vsamp[(size_t)s * (size_t)N + (size_t)(i - 1)];
ckt->CKTrhsOld[0] = 0.0;
for (i = 0; i <= N; i++)
ckt->CKTrhs[i] = 0.0;
/* (a) Settle the nonlinear device state at the FIXED node voltages v(t_s).
* In MODEINITFLOAT a junction device (diode/BJT/MOS) reads the node voltage
* but LIMITS the junction step against its stored internal voltage; a single
* load leaves it pinned at a stale bias (and MODEINITSMSIG alone reads the
* stored op-point, ignoring the node voltage -- the bug that made real diodes
* look linear). So load repeatedly: each pass walks the internal voltage
* toward the fixed node voltages until the limiter is a no-op. Behavioural/
* OSDI devices with no limiting settle on the first pass. */
ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEDCOP | MODEINITFLOAT;
{
int inner;
for (inner = 0; inner < 100; inner++) {
double bnorm = 0.0, dnorm = 0.0;
for (i = 0; i <= N; i++)
ckt->CKTrhs[i] = 0.0;
CKTload(ckt); /* reads CKTrhsOld (fixed v), evolves state0 */
for (i = 1; i <= N; i++) {
double db = ckt->CKTrhs[i] - bsave[i - 1];
dnorm += db * db;
bnorm += ckt->CKTrhs[i] * ckt->CKTrhs[i];
bsave[i - 1] = ckt->CKTrhs[i];
}
if (inner > 0 && sqrt(dnorm) <= 1e-12 * (sqrt(bnorm) + 1e-30))
break;
}
}
/* The settled MODEINITFLOAT load left the DC companion b = G*v - i(v) in
* bsave; it gives the ACTUAL resistive current i(v) = G*v - b for EVERY
* device (behavioural, OSDI, junction), not the tangent G*v.
* (b) A MODEINITSMSIG load then reads the now-settled junction state to build
* the small-signal linearization the AC (C) load needs. Its RHS is NOT the DC
* companion, so we do NOT overwrite bsave; but the small-signal G it sets up
* is the same di/dv at the settled bias, so I_R = G*v - b_float = i(v). */
for (i = 0; i <= N; i++)
ckt->CKTrhs[i] = 0.0;
ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEDCOP | MODEINITSMSIG;
CKTload(ckt);
/* companion source b = G*v - i(v) is in CKTrhs NOW; save it before acLoad
* clears it (so the resistive current is i(v) = G*v - b, the ACTUAL current,
* not the tangent G*v). */
for (i = 1; i <= N; i++)
bsave[i - 1] = ckt->CKTrhs[i];
ckt->CKTomega = 1.0;
ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEAC;
CKTacLoad(ckt); /* clears + stamps G (real) and C (imag) cleanly */
CKTacLoad(ckt); /* clears + stamps G (real) and C (imag) at the settled bias */
/* resistive current I_R = G*v - b, using the clean G from acLoad */
Gv = IRt + (size_t)s * (size_t)N; /* reuse row s as scratch, then subtract */