Spectrum Software
Industrial Strength Simulation




Spectrum Software has released Micro-Cap 11, the eleventh generation of our SPICE circuit simulator.

For users of previous Micro-Cap versions, check out the new features available in the latest version. For those of you who are new to Micro-Cap, take our features tour to see what Micro-Cap has to offer.




Questions and Answers - Fall 2003


Question: I have been running Dynamic DC analysis. When I display the currents, powers, or conditions, it can sometimes be difficult to determine which component the display belongs to. Is there a way to view which component the display is linked to?

Answer: There is a simple way to view which displays belong to a specific component. While in Dynamic DC analysis, enable the Select mode. In Select mode, click on one of the components in the schematic. Any displays associated with this component will be redrawn in the select color. This will work for any current, power, or condition display. Voltage displays are associated with a node and not a specific component so they will not be affected by this method.

Question: I am running a 100ms transient analysis on my schematic. The simulation gets to approximately the 30ms mark, and it then starts the simulation over again. It will then run through the entire simulation and any subsequent simulations. If I revert my circuit, I get the restart again during the first run. Why does the restart occur?

Answer: In the Preferences dialog box, there is an option called Convergence Assist which will be enabled. Convergence Assist is invoked if the simulation runs into convergence problems. It may modify Global Settings parameters such as RELTOL, ABSTOL, VNTOL, ITL2, ITL4, METHOD, GMIN, and others to achieve convergence. Since a change in the Global Settings can affect the SPICE matrix, the simulation needs to be restarted. If the assist succeeds, it adds a .OPTIONS statement to the text area of the circuit with the modified parameters so that subsequent runs converge more readily.

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