Recent changes to 33: Parametric Sweep NgSpice

#33 Parametric Sweep NgSpice

2021-01-12T12:02:57.416000Z

Could this ticket be reopened? It would be quite helpful to do a parametric DC sweep in the same way than PSPICE does:

.DC LIN PARAM Ik 1p 400p 1p

This would be needed to facilitate the KiCad ngspice integration, see discussion: https://gitlab.com/kicad/code/kicad/-/merge_requests/564#note_481539302

#33 Parametric Sweep NgSpice

2018-06-29T20:00:25.990000Z

status: open --> closed
assigned_to: Holger Vogt

#33 Parametric Sweep NgSpice

2018-06-29T19:59:54.582000Z

Command 'alterparam' to alter (and sweep) parameters is available in ngspice-28.

#33 Parametric Sweep NgSpice

2016-05-03T20:58:31.320000Z

You may use alter or altermod in subcircuits (manual, at the end of Chapt. 17.5.3).

After loading the circuit, use the command 'listing expand' (or 'listing expand > listtext.txt', if you want to put the output into a file listtext.txt). Then you may have a look at the subcircuits, how they are expanded, and what names to use in the alter command.

Holger

#33 Parametric Sweep NgSpice

2016-05-01T19:48:07.122000Z

Will this feature also support subcircuit parameter sweeps ? If possible kindly support this too. "alter" and "altermod" can not be used for this purpose.

#33 Parametric Sweep NgSpice

2015-11-14T15:18:38.153000Z

please have a look at manual chapter
16.13.4.2 .step

Holger

#33 Parametric Sweep NgSpice

2015-11-13T14:21:54.895000Z

I would also like to have this parameter change method. It is interesting when you have to test the behaviour of a trimmer or a trimpot in a filter circuit (like an graphic equalizer, for example).

I can use the alter command and the only problem is that the script will be longer and more prone to mistakes. The bad part about this is that you can´t save vectors between runs (with different names) so you can plot them stacked for comparison reasons. Almost all simulators have this feature.

#33 Parametric Sweep NgSpice

2014-05-03T13:52:07.012000Z

It ain't pretty ...
The main problem was that ALTER changes the device directly, you
don't need to go through the parameter. Also, the alpha_T in the
control loop can't be a parameter because a control section
is a third interpreter layer :-E

I didn't make it plot, sorry. You probably will need to read in
the diskfile again, assign the scale/value columns to variables,
and then plot.

Note that diskfile contains paired scale/value columns. The actual
value of the scales is a bit mysterious, maybe somebody else can
explain.

-marcel

Test sweeping

Vin 1 0 1
R1  1 2 1k
R2  2 0 200
.tran 1ms 10ms

.control
 let start_T = 20
 let stop_T  = 30
 let delta_T = 1
 let T_act   = start_T
 let alpha_T = -0.001
 let new_R   = 200

 while T_act le stop_T
     let new_R = 200 * (1 + alpha_T * T_act)
     alter r2 new_R
     run
     wrdata sweepT.out v(2) v(1) T_act new_R
     set appendwrite
     let T_act = T_act + delta_T
 end
asciiplot v(2) v(1)
.endc

.end

#33 Parametric Sweep NgSpice

2014-05-03T09:44:27.143000Z

Thank you Marcel

I tried Let and Alter

VDin 1 0 1
R1 1 2 1k
R2 2 0 r={200*(1+alpha_T * T)}
.tran 1ms 10ms

.control
let start_T = 20
let stop_T = 30
let delta_T = 1
let T_act = start_T
*loop
while T_act le stop_T
alter T T_act
run
wrdata sweepT.out v(2) v(1) T_act
set appendwrite
let T_act = T_act + delta_T
end
plot v(2) v(1)
.endc
.end
but this code didn't work cause the values wasn't right in the file sweepT and when i tried to plot the T_act, i got an error "T_act isn't a vector"

#33 Parametric Sweep NgSpice

2014-05-03T09:08:43.337000Z

Did you look at LET and ALTER in the manual?

-marcel