The .OP statement requests a DC operating point analysis. The simulator computes the quiescent (steady-state) voltages and currents of the circuit with no time-varying or frequency-domain stimuli.
.OP
No parameters are required.
Voltage divider
V1 VCC 0 12
R1 VCC OUT 1k
R2 OUT 0 2k
.OP
.SAVE V(OUT)
.END
The operating point of V(OUT) will be computed as 8 V (voltage divider:
$12\cdot 2k/(1k + 2k)$).
.OP solves the real-valued DC MNA system. Capacitors behave like open circuits
in the DC limit, inductors behave like short branch relations, and nonlinear
devices are solved by Newton iteration.
The simulator repeatedly loads the matrix and RHS until the operating point converges:
load DC/Newton matrix
solve Y*x = rhs
update nonlinear device guesses
repeat until convergence
For the full matrix algorithm, see How SpiceSharp Solves Circuits.
.OP is commonly used to:
- Verify bias points in amplifier circuits
- Check quiescent currents through components
- Debug circuit connectivity before running transient or AC simulations
var sim = model.Simulations.Single(); // OP simulation
var vout = model.Exports.Find(e => e.Name == "V(OUT)");
sim.EventExportData += (s, args) =>
{
Console.WriteLine($"V(OUT) = {vout.Extract()}");
};