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The Design Explorer-based Circuit Simulator is a true mixed-mode simulator, meaning that it can analyze circuits that include both analog and digital devices.
The Simulator uses an enhanced version of the event-driven XSPICE, developed by the Georgia Tech Research Institute (GTRI), which itself is based on Berkeley's SPICE3 code. It is fully SPICE3f5 compatible.
The models supported by the Simulator can be effectively grouped into the following categories:
SPICE3f5 analog models
These are predefined analog device models that are built-in to SPICE. They cover the various common analog component types, such as resistors, capacitors and inductors, as well as voltage and current sources, transmission lines and switches. The five most common semiconductor devices are also modeled - diodes, BJTs, JFETs, MESFETs and MOSFETs.
A large number of model files (*.mdl) are also included, that define the behavior of specific instances of these devices.
XSPICE analog models
These are predefined analog device code models that are built-in to XSPICE. Code models allow the specification of complex, non-ideal device characteristics, without the need to develop long-winded sub-circuit definitions that can adversely affect Simulator speed performance. The supplied models cover special functions such as gain, hysteresis, voltage and current limiting and definitions of s-domain transfer functions.
The SPICE prefix for theses models is A.
Sub-Circuit models
These are models for more complex devices, such as operational amplifiers, timers, crystals, etc, that have been described using the hierarchical sub-circuit syntax.
A sub-circuit consists of SPICE elements that are defined and referenced in a fashion similar to device models. There is no limit on the size or complexity of sub-circuits and sub-circuits can call other sub-circuits. Each sub-circuit is defined in a sub-circuit file (*.ckt).
The SPICE prefix for theses models is X.
Digital models
These are digital device models that have been created using the Digital SimCode language. This is a special descriptive language that allows digital devices to be simulated using an extended version of the event-driven XSPICE. It is a form of the standard XSPICE code model.
Source SimCode model definitions are stored in an ASCII text file (*.txt). Compiled SimCode models are stored in a compiled model file (*.scb). Multiple device models can be placed in the same file, with each reference by means of a special "func=" parameter.
The SPICE prefix for theses models is A.
Digital SimCode is a proprietary language - devices created with it are not compatible with other simulators, nor are digital components created for other simulators compatible with the Design Explorer-based mixed-mode Simulator.
Notes
For more detailed information concerning SPICE and XSPICE, consult the respective user manuals for each. The XSpice manual is particularly useful for learning about the syntax required for the Code Models added to XSPICE by GTRI and extensions that have been made to SPICE3.
Many of the component libraries (*.IntLib) that come with the installation, feature simulation-ready devices. These devices have the necessary model or sub-circuit file included and linked to the schematic component. These are pure SPICE models for maximum compatibility with analog simulators.
There were no syntax changes made between SPICE3f3 and SPICE3f5. The manual for SPICE3f3 therefore describes the correct syntax for the netlist and models supported by the Design Explorer-based mixed-mode Simulator.
Links
Component and Simulation Multipliers
Simulation-ready Components - Quick Reference