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pa-126

This commit is contained in:
Meisam Bahadori 2026-07-26 11:15:52 +02:00 committed by Holger Vogt
parent 89cf69d4ee
commit 11e8d318b3
4 changed files with 117 additions and 3 deletions
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4
src/include/ngspice/pssdefs.h
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@ -58,6 +58,9 @@ typedef struct {
int PSSdoPnoise; /* 1 if this job runs a pnoise sweep */
CKTnode *PnOutNode; /* pnoise output node (reference = ground) */
IFuid PnInSrc; /* input source name, for the input-referred spectrum */
int PSSpnCyclo; /* Enhancement-126: 1 = cyclostationary noise (per-sample
* bias + time-domain transfer, averaged over the period);
* 0 = stationary (noise PSD at one operating point) */
/* Enhancement-125: periodic transfer function (.pxf). The ADJOINT counterpart of
* PAC: solve Hᵀ Ψ = e_{out,0} and dot Ψ with the netlist AC-source pattern to get
@ -87,6 +90,7 @@ enum {
PNOISE_INSRC,
PXF_DO,
PXF_OUT,
PNOISE_CYCLO,
};
#endif

91
src/spicelib/analysis/dcpss.c
View File

@ -769,10 +769,97 @@ pnoise_sweep(CKTcircuit *ckt, PSSan *job)
linstep = (np > 1) ? (fstop - fstart) / (np - 1) : 0.0;
fprintf(stderr, "PNOISE sweep: %s from %.6g to %.6g Hz around f0 = %.6g Hz; "
"output node %d; folding %d sidebands\n",
"output node %d; folding %d sidebands%s\n",
(stepType == 1) ? "dec" : (stepType == 2) ? "oct" : "lin",
fstart, fstop, f0, outNode, 2*M + 1);
fstart, fstop, f0, outNode, 2*M + 1,
job->PSSpnCyclo ? "; cyclostationary" : "");
if (job->PSSpnCyclo) {
/* Enhancement-126: cyclostationary noise. The device noise PSD S(t) varies
* along the PSS period, and its harmonics couple sidebands. Using the
* identity onoise = (1/P) Σ_s S(t_s)·|ΔA_s|², where A_s(j) = Σ_k Ψ_k(j)·
* exp(j·2π·k·s/P) is the inverse-DFT of the sideband adjoint transfers, this
* is computed by evaluating each device's noise at every sample's bias
* (CKTload per sample) and folding through the time-domain transfer, then
* averaging over the period. Reduces to the stationary case (and hence
* .noise) when S(t) is constant, by Parseval. */
long P = job->PSSopPoints, s;
int Nf = 0, fi, c;
double *freqs, *onz, *Pr_all, *Pi_all;
for (freq = fstart; freq <= fstop * (1.0 + 1e-9); ) { /* count points */
Nf++;
if (stepType == 0) { if (np <= 1) break; freq += linstep; }
else { freq *= mult; }
}
freqs = TMALLOC(double, Nf);
onz = TMALLOC(double, Nf);
Pr_all = TMALLOC(double, (size_t)Nf * (size_t)hd.Ntot);
Pi_all = TMALLOC(double, (size_t)Nf * (size_t)hd.Ntot);
c = 0;
for (freq = fstart; freq <= fstop * (1.0 + 1e-9); ) { /* fill + adjoints */
freqs[c] = freq; onz[c] = 0.0;
if (pac_solve_adjoint(&hd, f0, freq, outNode, Psr, Psi) != 0) {
memset(Psr, 0, (size_t)hd.Ntot * sizeof(double));
memset(Psi, 0, (size_t)hd.Ntot * sizeof(double));
}
memcpy(Pr_all + (size_t)c * (size_t)hd.Ntot, Psr, (size_t)hd.Ntot * sizeof(double));
memcpy(Pi_all + (size_t)c * (size_t)hd.Ntot, Psi, (size_t)hd.Ntot * sizeof(double));
c++;
if (stepType == 0) { if (np <= 1) break; freq += linstep; }
else { freq *= mult; }
}
for (s = 0; s < P; s++) { /* evaluate device noise at each sample's bias */
double ang0 = 2.0 * M_PI * (double)s / (double)P;
for (i = 1; i <= N; i++)
ckt->CKTrhsOld[i] = job->PSSopVoltages[(i - 1) + s * N];
ckt->CKTrhsOld[0] = 0.0;
if (ns > 0)
memcpy(ckt->CKTstate0, job->PSSopStates + (size_t)s * (size_t)ns,
(size_t)ns * sizeof(double));
ckt->CKTmode = (ckt->CKTmode & MODEUIC) | MODEDCOP | MODEINITSMSIG;
CKTload(ckt);
for (fi = 0; fi < Nf; fi++) {
double dens = 0.0;
double *pr = Pr_all + (size_t)fi * (size_t)hd.Ntot;
double *pi = Pi_all + (size_t)fi * (size_t)hd.Ntot;
for (j = 1; j <= N; j++) { /* A_s(j) = IDFT_k Ψ_k(j) */
double ar = 0.0, ai = 0.0;
for (k = -M; k <= M; k++) {
size_t idx = (size_t)(k + M) * (size_t)N + (size_t)(j - 1);
double cs = cos((double)k * ang0), sn = sin((double)k * ang0);
ar += pr[idx] * cs - pi[idx] * sn;
ai += pr[idx] * sn + pi[idx] * cs;
}
ckt->CKTrhs[j] = ar; ckt->CKTirhs[j] = ai;
}
ckt->CKTrhs[0] = 0.0; ckt->CKTirhs[0] = 0.0;
data.freq = freqs[fi]; data.delFreq = 0.0; data.prtSummary = FALSE;
for (i = 0; i < DEVmaxnum; i++)
if (DEVices[i] && DEVices[i]->DEVnoise && ckt->CKThead[i])
DEVices[i]->DEVnoise(N_DENS, N_CALC, ckt->CKThead[i],
ckt, &data, &dens);
onz[fi] += dens;
}
}
for (fi = 0; fi < Nf; fi++) { /* period-average, gain, output */
double onoise = onz[fi] / (double)P, gain2 = 1.0, gsi;
IFvalue refVal, valData;
double out[2];
if (hd.has_src && pac_solve_at(&hd, f0, freqs[fi], outNode, 1, Xr, Xi) == 0) {
size_t oidx = (size_t)M * (size_t)N + (size_t)(outNode - 1);
gain2 = Xr[oidx] * Xr[oidx] + Xi[oidx] * Xi[oidx];
}
gsi = 1.0 / MAX(gain2, N_MINGAIN);
out[0] = onoise; out[1] = onoise * gsi;
refVal.rValue = freqs[fi];
valData.v.numValue = 2; valData.v.vec.rVec = out;
SPfrontEnd->OUTpData(plot, &refVal, &valData);
}
FREE(freqs); FREE(onz); FREE(Pr_all); FREE(Pi_all);
} else
for (freq = fstart; freq <= fstop * (1.0 + 1e-9); ) {
double onoise = 0.0, gain2 = 1.0, gsi;

8
src/spicelib/analysis/psssetp.c
View File

@ -86,6 +86,11 @@ PSSsetParm(CKTcircuit *ckt, JOB *anal, int which, IFvalue *value)
job->PxOutNode = value->nValue;
break;
/* Enhancement-126: cyclostationary-noise flag */
case PNOISE_CYCLO:
job->PSSpnCyclo = value->iValue;
break;
default:
return(E_BADPARM);
}
@ -112,7 +117,8 @@ static IFparm PSSparms[] = {
{ "pnoise_out", PNOISE_OUT, IF_SET|IF_STRING, "pnoise output node" },
{ "pnoise_insrc", PNOISE_INSRC, IF_SET|IF_STRING, "pnoise input source (for the input-referred spectrum)" },
{ "pxf", PXF_DO, IF_SET|IF_INTEGER, "run a periodic transfer-function sweep after PSS" },
{ "pxf_out", PXF_OUT, IF_SET|IF_STRING, "pxf output node" }
{ "pxf_out", PXF_OUT, IF_SET|IF_STRING, "pxf output node" },
{ "pnoise_cyclo", PNOISE_CYCLO, IF_SET|IF_INTEGER, "pnoise cyclostationary mode (per-sample bias, period average)" }
};
SPICEanalysis PSSinfo = {

17
src/spicelib/parser/inp2dot.c
View File

@ -854,6 +854,23 @@ dot_pnoise(char *line, void *ckt, INPtables *tab, struct card *current,
parm = INPgetValue(ckt, &line, IF_REAL, tab); /* fstop */
GCA(INPapName, (ckt, which, foo, "pac_fstop", parm));
{ /* Enhancement-126: optional trailing "cyclo" keyword */
char *p = line;
while (*p == ' ' || *p == '\t')
p++;
if (*p) {
char *word;
INPgetTok(&line, &word, 1);
if (strcmp(word, "cyclo") == 0) {
ptemp.iValue = 1;
GCA(INPapName, (ckt, which, foo, "pnoise_cyclo", &ptemp));
} else {
fprintf(stderr, "Error: unknown parameter %s on .pnoise - ignored\n", word);
}
tfree(word);
}
}
ptemp.iValue = 1; /* enable the pnoise sweep */
GCA(INPapName, (ckt, which, foo, "pnoise", &ptemp));