Code-level modeling in XSPICE

Describes code-level modeling in XSPICE, an extended version of the SPICE3 simulator from the University of California at Berkeley. XSPICE extends SPICE3´s capabilities to allow efficient simulation of mixed-signal (analog/digital) circuits and systems. XSPICE´s code-level modeling approach allows new models to be easily added to the SPICE3 core, providing a practical alternative to traditional macromodeling techniques. Addition of event-driven simulation extends SPICE3 to include 12-state digital modeling. User-defined data types allow simulation of designs such as sampled-data filters. A library of over 40 predefined code models has been developed, covering analog, digital, and hybrid devices and functions. The complete XSPICE simulator has been integrated with the Mentor Graphics MSPICE CAE (computer-aided engineering) environment, and provides a general interprocess communication interface for connection to other CAE system software. An example illustrating the use of XSPICE in top-down, system-level design is shown. The system is a simple MIDI (musical instrument digital interface) synthesizer