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.




AC Analysis


I am running an AC analysis on one of my circuits. I have a sine source in the schematic that provides the AC stimulus. However, when I run the simulation, the output node that I am looking at is producing a constant 0 which is in error. In the AC analysis limits, I have disabled the Operating Point option. What is going wrong?


In order to be able to disable the operating point, the State Variables option in the AC Analysis Limits must be set to Read or Leave. The definition of AC analysis is that it is a linear, small signal analysis. Micro-Cap constructs a small signal representation of the circuit for the analysis. Typically, Micro-Cap obtains the small signal models by linearizing the devices about the operating point calculations. If the State Variables is set to Read or Leave, then the responsibility of determining accurate and true state variables lies with the user. If using the Read option, there must be a previously saved state variables file for the circuit, and if using the Leave option, there must be the correct values available in the State Variables Editor. If the complete state variables are not supplied by the user when Read or Leave is selected, the run will not be meaningful.






AC Analysis
Analysis - General
DC Analysis
Dynamic DC
Initial Conditions
Monte Carlo
Schematic Editor
Transient Analysis