// Param sweep .STEP param C 1n 100n 10n

LTspice (free, best for beginners), ngspice (open-source), PSpice (commercial), HSPICE (high-precision).

| Problem | Likely Cause | Solution | |---------|--------------|----------| | "Singular matrix" | Floating node (no DC path to ground) | Add a huge resistor (1GΩ) to ground | | Unrealistic fast edges | Missing parasitic capacitance | Add Cpar=1p to inductors/diodes | | Simulation too slow | Too small timestep | Use .OPTIONS reltol=1e-3 or increase max timestep | | No current through cap | DC analysis (capacitor = open) | Use .TRAN for transient current |

is always ground.

Spice Circuit Now

// Param sweep .STEP param C 1n 100n 10n

LTspice (free, best for beginners), ngspice (open-source), PSpice (commercial), HSPICE (high-precision). spice circuit

| Problem | Likely Cause | Solution | |---------|--------------|----------| | "Singular matrix" | Floating node (no DC path to ground) | Add a huge resistor (1GΩ) to ground | | Unrealistic fast edges | Missing parasitic capacitance | Add Cpar=1p to inductors/diodes | | Simulation too slow | Too small timestep | Use .OPTIONS reltol=1e-3 or increase max timestep | | No current through cap | DC analysis (capacitor = open) | Use .TRAN for transient current | // Param sweep

is always ground.