Transient Test


The transient analysis generates the circuit's behavior over time, from tstart to tstop. The maximum interval between time steps, tmax, is critical to prevent the simulation from generating incorrect results. If tmax is too high, then sharp changes in the circuit's voltages may be overlooked by the simulator. The program gives you the option to linearize results, which will cause SPICE to generate a second transient graph, with results linearized at an interval of tstep. The Transient Test is similar to the default Simulation, but the time span is defined and the results are displayed in a graph instead of the virtual instruments.

Sometimes Spice has trouble converging on solutions with the transient analysis. If this happens, sometimes increasing capacitances and internal transistor capacitances specified in transistor models can relax the circuit enough to help convergence. Also, sometimes increasing the itl4 option (in the Simulation Options... dialog) from its default of 10 to around 40 can help.

The following graph is the result of running a Transient test on Tut2.ckt


param_trans_graph.gif (5131 bytes)

Transient Parameter Sweep

The parameterized transient sweep runs a set of transient analyses with a parameter changing its value for each transient sweep. In the screens shown below, the example circuit's resistor is swept from a resistance of 1 Ohm  to 51 Ohm at every 10 Ohms.  The resulting graphs (shown above) plot the output voltage at every resistance step.