Hello, this is an issue related to #C0750383B2M I am having trouble with parametric noise runs. The core problem is this bit of code:

alter vvgs_ctrl 0.8
  op
  print Vp1p8hvt#branch
  noise v(src_n1p8lvt) Vvgs_ctrl dec 1000 100 10e9
  print onoise_total
  ; reset
  alter vvgs_ctrl 1.2
  op
  print Vp1p8hvt#branch
  noise v(src_n1p8lvt) Vvgs_ctrl dec 1000 100 10e9
  print onoise_total

This is the core of my loop, I alter a parameter and then re-run the simulation. I have included the

op

command just to verify the

alter

command is doing something. This is what it returns:

Using SPARSE 1.3 as Direct Linear Solver
 Reference value :  0.00000e+00
No. of Data Rows : 1
vp1p8hvt#branch = 5.9080065507013344e-07
Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver

No. of Data Rows : 8001

No. of Data Rows : 1
onoise_total = 1.2877645416968548e-05
Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver

No. of Data Rows : 1
vp1p8hvt#branch = 2.3014385629361719e-05
Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver

No. of Data Rows : 8001

No. of Data Rows : 1
onoise_total = 1.2879064884219959e-05

The branch current increases, however the output noise seems to return the original value. When I simulate at

vctrl=1.2

directly, I get the (expected) noise increase. I saw this: https://sourceforge.net/p/ngspice/discussion/133842/thread/fcd70adf/ So I tried adding the

reset

command, but it kills the sim:

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver

No. of Data Rows : 1
vp1p8hvt#branch = 2.3014385629361719e-05
Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver
Error: no data saved for Noise analysis; analysis not run
doAnalyses: not found

noise simulation(s) aborted
Warning from checkvalid: vector onoise_total is not available or has zero length.

Any ideas? Thank you.

This works fine for me (with reset). Perhaps there is something going on outside this core that you're showing?

Thanks for trying it out! I wonder if it’s somehow related to OSX or my versions? I removed all the other stuff, and just run this control line.

.control
  save all
  noise v(src_n1p8lvt) Vvgs_ctrl dec 1000 100 10e9
  reset
  noise v(src_n1p8lvt) Vvgs_ctrl dec 1000 100 10e9
.endc

I just tried the following versions: Version 4.4, installed via homebrew (pre-compiled)

******
** ngspice-44.2 : Circuit level simulation program
** Compiled with KLU Direct Linear Solver
** The U. C. Berkeley CAD Group
** Copyright 1985-1994, Regents of the University of California.
** Copyright 2001-2024, The ngspice team.
** Please get your ngspice manual from <https://ngspice.sourceforge.io/docs.html>
** Please file your bug-reports at <http://ngspice.sourceforge.net/bugrep.html>
******
Warning: locale not supported by Xlib, locale set to C
Warning: X locale modifiers not supported, using default

Note: No compatibility mode selected!


Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver
 Reference value :  1.00000e+02
No. of Data Rows : 8001

No. of Data Rows : 1
Reset re-loads circuit ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver
Error: no data saved for Noise analysis; analysis not run
doAnalyses: not found

noise simulation(s) aborted

I compiled version 4.2 myself, from the tarball release download:

******
** ngspice-42 : Circuit level simulation program
** Compiled with Sparse Direct Linear Solver
** The U. C. Berkeley CAD Group
** Copyright 1985-1994, Regents of the University of California.
** Copyright 2001-2023, The ngspice team.
** Please get your ngspice manual from <https://ngspice.sourceforge.io/docs.html>
** Please file your bug-reports at <http://ngspice.sourceforge.net/bugrep.html>
******

Note: No compatibility mode selected!


Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

 Reference value :  1.00000e+02
No. of Data Rows : 8001

No. of Data Rows : 1
Reset re-loads circuit ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Error: no data saved for Noise analysis; analysis not run
doAnalyses: not found

noise simulation(s) aborted

Compiled version 4.4+ from hash dd916b1d0e03a8a441d998291897424cf956ee92

******
** ngspice-44+ : Circuit level simulation program
** Compiled with KLU Direct Linear Solver
** The U. C. Berkeley CAD Group
** Copyright 1985-1994, Regents of the University of California.
** Copyright 2001-2024, The ngspice team.
** Please get your ngspice manual from <https://ngspice.sourceforge.io/docs.html>
** Please file your bug-reports at <http://ngspice.sourceforge.net/bugrep.html>
******

Note: No compatibility mode selected!


Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver
 Reference value :  1.00000e+02
No. of Data Rows : 8001

No. of Data Rows : 1
Reset re-loads circuit ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Circuit: ** sch_path: /users/colinww/foss/work/device_char/device_char.sch

Doing analysis at TEMP = 27.000000 and TNOM = 27.000000

Using SPARSE 1.3 as Direct Linear Solver
Error: no data saved for Noise analysis; analysis not run
doAnalyses: not found

noise simulation(s) aborted

Fundamentally, it seems like I can’t run a noise analysis after the

reset

command. I could dig into the source if someone gives a general idea of what this message means:

Error: no data saved for Noise analysis; analysis not run

I don't need the

save all

for it to work. Is

src_n1p8lvt

a "regular" node in your circuit?

Yeah, just top level connectivity. It’s not some internal macromodel node like the ST models used to do, if that’s what you meant. I agree it’s odd, but still not the oddest thing I’ve encountered with this flow in the past few days 🙂