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pa-63

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Meisam Bahadori 2026-07-22 14:48:00 +02:00 committed by Holger Vogt
parent 3cdce8bef7
commit b54bf483fb
1 changed files with 12 additions and 1 deletions
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13
src/spicelib/analysis/span.c
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@ -142,7 +142,18 @@ CKTspnoise(CKTcircuit* ckt, int mode, int operation, Ndata* data, NOISEAN* noise
double Gu = tempCy->d[0][0].re - Rn * Y11_Ycor;
cplx Ysopt; Ysopt.re = sqrt(SQR(Ycor.re) + Gu / Rn); Ysopt.im = -Ycor.im;
/* Enhancement-63: the uncorrelated noise conductance Gu (and
with it the sqrt argument below) is physically >= 0, but for
a fully-correlated noise topology (e.g. a single series
resistor as the only noise source) it is analytically ZERO
and floating-point rounding can land it at -1e-18 --
sqrt(negative) then poisons NF/SOpt/NFmin/Rn with NaN.
Clamp to the physical range. */
double YsoptArg = SQR(Ycor.re) + Gu / Rn;
if (YsoptArg < 0.0)
YsoptArg = 0.0;
cplx Ysopt; Ysopt.re = sqrt(YsoptArg); Ysopt.im = -Ycor.im;
cplx Y0; Y0.re = refPortY0; Y0.im = 0.0;
Sopt = cdivco(csubco(Y0, Ysopt),
caddco(Y0, Ysopt));