XSPICE is an extension to the SPICE3 circuit simulator that provides the ability to use code modeling techniques to add new models. The XSPICE code model library contains over 40 new functional blocks including summers, multipliers, integrators, magnetics models, limiters, S-domain transfer functions, digital gates, digital storage elements, and a generalized digital state-machine. XSPICE was developed by Fred Cox and his colleagues at the Georgia Tech Research Institute, a unit of the Georgia Institute of Technology.
Digital functions are simulated in XSPICE through an embedded event-driven algorithm added to the SPICE core. This algorithm is coordinated with the analog simulation algorithm to provide fast and accurate simulation of mixed-signal circuits and systems. The event-driven algorithm supports a "User-Defined Node" capability allowing additional event-driven data types to be defined and used. XSPICE comes with a 12-state digital data type as well as a user-defined node library that includes 'real' and 'integer' types useful in simulating sampled-data systems such as Digital Signal Processing algorithms.
XSPICE has been placed in the public domain by the Georgia Institute of Technology. It is available for download from this web site in source code form, allowing users to customize and extend the simulator and models to particular needs. The code and documentation below is provided free of charge as a community service. No technical support is available.