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pa-177

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Meisam 2026-07-28 17:52:49 +02:00 committed by Holger Vogt
parent 5887fb8dff
commit d75cdc264d
1 changed files with 36 additions and 4 deletions
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40
src/spicelib/analysis/dcpss.c
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@ -851,7 +851,16 @@ pnoise_sweep(CKTcircuit *ckt, PSSan *job)
* 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. */
* .noise) when S(t) is constant, by Parseval.
*
* Enhancement-177 note: this time-domain identity treats the source
* PSD as FREQUENCY-FLAT across the folding span (exact for
* modulated-white noise). A frequency-dependent PSD (flicker) folded
* through k != 0 conversion cannot be collapsed into the |A_s|^2
* product with the aggregate device-noise API; use the stationary
* mode (which evaluates each sideband at its own source frequency,
* E-177) when folded flicker matters. The shipped cyclo use cases
* (modulated white; flicker on conversion-free circuits) are exact. */
long P = job->PSSopPoints, s;
int Nf = 0, fi, c;
double *freqs, *onz, *Pr_all, *Pi_all;
@ -932,7 +941,6 @@ pnoise_sweep(CKTcircuit *ckt, PSSan *job)
for (freq = fstart; freq <= fstop * (1.0 + 1e-9); ) {
double onoise = 0.0, gain2 = 1.0, gsi;
data.freq = freq;
data.delFreq = 0.0; /* density only -- we do not integrate here */
data.prtSummary = FALSE;
@ -941,6 +949,15 @@ pnoise_sweep(CKTcircuit *ckt, PSSan *job)
for (k = -M; k <= M; k++) {
double dens = 0.0;
size_t blk = (size_t)(k + M) * (size_t)N;
/* Enhancement-177: the sideband-k adjoint carries noise that
* ORIGINATES at the physical frequency |freq + k*f0| -- a
* frequency-dependent source PSD (flicker 1/f, noise_table)
* must be evaluated THERE, not at the output frequency.
* (White sources are flat, and LTI circuits have no k != 0
* transfer, which is why every earlier check passed.) */
data.freq = fabs(freq + (double)k * f0);
if (data.freq == 0.0)
data.freq = freq; /* exact-hit guard (1/f at dc) */
for (j = 1; j <= N; j++) {
ckt->CKTrhs[j] = Psr[blk + (size_t)(j - 1)];
ckt->CKTirhs[j] = Psi[blk + (size_t)(j - 1)];
@ -2351,6 +2368,11 @@ QPnoiseAnalyze(CKTcircuit *ckt, int outNode, double f_in, int cyclo, int verbose
for (hi = 0; hi < Nh; hi++) {
double dens = 0.0;
size_t blk = (size_t)hi * (size_t)N;
/* Enhancement-177: evaluate the source PSD at the harmonic's
* own physical frequency (see pnoise_sweep). */
data.freq = fabs(f_in + hd->h1[hi] * hd->f1 + hd->h2[hi] * hd->f2);
if (data.freq == 0.0)
data.freq = f_in;
for (j = 1; j <= N; j++) {
ckt->CKTrhs[j] = Psr[blk + (size_t)(j-1)];
ckt->CKTirhs[j] = Psi[blk + (size_t)(j-1)];
@ -2368,7 +2390,10 @@ QPnoiseAnalyze(CKTcircuit *ckt, int outNode, double f_in, int cyclo, int verbose
* is the TIME-domain transfer at 2-D phase sample s = (s1,s2). Evaluate
* each device's noise at every sample's bias (v(theta1,theta2) from the
* retained V) and average over the P1xP2 grid. By Parseval this reduces to
* the stationary sum (and hence .noise) when S(t) is constant. */
* the stationary sum (and hence .noise) when S(t) is constant.
* (E-177: same frequency-flat assumption as the single-tone cyclo
* path -- exact for modulated-white; use stationary mode for folded
* flicker.) */
int P1 = hd->P1, P2 = hd->P2, s1, s2;
int Ptot = P1 * P2;
double *vsamp = TMALLOC(double, (size_t)N * (size_t)Ptot);
@ -2893,10 +2918,17 @@ PhaseNoiseAnalyze(CKTcircuit *ckt, double fstart, double fstop, int npts, int ve
memset(Psi, 0, (size_t)Ntot*sizeof(double));
Psr[(size_t)(M+1)*(size_t)N + (size_t)(onode-1)] = 1.0; /* carrier sideband m=1 */
if (pss_csolve(Ntot, Ar, Ai, Psr, Psi) == 0) {
data.freq = freq; data.delFreq = 0.0; data.prtSummary = FALSE;
data.delFreq = 0.0; data.prtSummary = FALSE;
for (k = -M; k <= M; k++) {
double dens = 0.0;
size_t blk = (size_t)(k+M)*(size_t)N;
/* Enhancement-177: sideband k folds noise ORIGINATING at
* |freq + k*f0| -- crucial for the flicker (1/f^3) region,
* where evaluating the folded far-sideband blocks at the tiny
* offset frequency would wildly overweight them. */
data.freq = fabs(freq + (double)k * f0);
if (data.freq == 0.0)
data.freq = freq;
for (j = 1; j <= N; j++) { ckt->CKTrhs[j] = Psr[blk+(size_t)(j-1)]; ckt->CKTirhs[j] = Psi[blk+(size_t)(j-1)]; }
ckt->CKTrhs[0] = 0.0; ckt->CKTirhs[0] = 0.0;
for (ei = 0; ei < DEVmaxnum; ei++)