"op" command


Performs a nonlinear DC steady state analysis, with no input. If a temperature range is given, it sweeps the temperature.


op start stop stepsize {options ...} 


There are substantial extensions beyond the capabilities of the SPICE op command.

If there are numeric arguments, they represent a temperature sweep. They are the start and stop temperatures in degrees Celsius, and the step size, in order. They are saved between commands, so no arguments will repeat the previous sweep.

This command will use the op probe set, instead of automatically printing all nodes and source currents, so you must do “print op ….” before running op. We did it this way because we believe that printing everything all the time is usually unnecessary clutter. All of the information available from SPICE and more is available here. See the print command and the device descriptions for more details.

A single parameter represents a single temperature. Two parameters instruct the computer to analyze for those two points only.

This command also sets up the quiescent point for subsequent AC analysis. It is necessary to do this for nonlinear circuits. The last step in the sweep determines the quiescent point for the AC analysis.


Sweep control

* multiplier Log sweep. Multiply the input by multiplier to get the next step. Do not pass zero volts!!
by stepsize Linear sweep. Add stepsize to get the next step.
decade steps Log sweep. Use steps steps per decade.
times multiplier Log sweep. Multiply the input by multiplier to get the next step. Do not pass zero volts!!
continue Use the last step of a OP, DC or Transient analysis as the first guess.
loop Repeat the sweep, backwards.
reverse Sweep in the opposite direction.

Input / Output

> file Send results of analysis to file.
» file Append results to file.
noplot Suppress plotting.
plot Graphic output, when plotting is normally off.
quiet Suppress console output.


dtemp degrees Temperature offset, degrees C. Add this number to the temperature from the options command.
temperature degrees Temperature, degrees C.
trace off No extended trace information.
trace warnings Show extended warnings.
trace iterations Show every iteration.
trace verbose Show extended diagnostics.


op 27

Do a DC operating point simulation at temperature 27 degrees Celsius.

op -50 200 25

Sweep the temperature from -50 to 200 in 25 degree steps. Do a DC operating point simulation at each step.


With no parameters, it uses the same ones as the last time. In this case, from -50 to 200 in 25 degree steps.

op 200 -50 -25

You can sweep downward, by asking for a negative increment.

op temperature=75

Simulate at 75 degrees, this time. This isn't remembered for next time.


Since the last time used the temperature option, go back one more to find what the sweep parameters were. In this case, downward from 200 to -50 in 25 degree steps.

gnucap/manual/commands/op.txt · Last modified: 2015/12/11 15:39 (external edit)
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