ngspice: enable .dc current, temperature and resistance sweeps

[Holger Vogt]

This is an extension to report https://bugs.launchpad.net/kicad/+bug/1786126

The .dc command in ngspice (in addition to sweeping a voltage) allows sweeping the current of a current source that is in the netlist, the temperature of the simulation or sweeping the value of a resistor that is in the netlist.

The command for sweeping the temperature is
.dc TEMP -15 75 5
During simulation a scale (x axis) vector temp-sweep is generated, which is used for plotting.

Combining the temperature sweep with another sweep is possible, e.g.
.dc V1 0 5 0.1 TEMP -15 75 5
Here for each temperature the voltage V1 is swept. vector temp-sweep is not generated, but vector v-sweep.

.dc TEMP -15 75 0.5 V2 0 5 1
For each voltage V2 the temperature is swept. vector temp-sweep is generated and has to be available for plotting.

The command for a resistance sweep in combination with a voltage sweep is
.dc R2 5 10 1 V1 0 1 100m
The scale vector res-sweep is generated and used as x axis vector for plotting

The command for a current sweep in combination with a resistance sweep is
.dc I1 0 1 100m R2 5 10 1
The scale vector i-sweep is generated and used as x axis vector for plotting

Eeschema --> Tools --> Simulator --> Settings --> DC Transfer
should be modified, e.g. by exclusive radio buttons V, I, T, R, each for primary and secondary selection, next to the enable button. The drop-down files DC Source should then offer only the V, I, R available in the netlist. In case of T being selected, the drop-down should grey out. Some value checking for start or end point might be done (R > 0, T > -273.15 °C).

[Wayne Stambaugh (stambaughw)]

I wouldn't mind seeing this implemented myself.

[Sylwester Kocjan (skocjan)]

Hi,

I wonder if radio buttons are necessary here. Drop-down list can contain all the elements: V and I sources, resistors and additional element: TEMP.

Moreover, I think we should get rid of one of Enable checkbox: first item must be always included in .dc command. Second item can be enabled if necessary. Two more ideas:

- controls for second item can be disabled when checkbox will be cleared
- text fields indicating units (Volts, Amperes, gr. C) can change depending on selected item in list.

In the attachment you can find my proposals for this feature.

[Sylwester Kocjan (skocjan)]

This is screenshot how it can look like

[Sylwester Kocjan (skocjan)]

This is partly modified fbp file

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2370