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49 lines
2.4 KiB
Plaintext
49 lines
2.4 KiB
Plaintext
ACS is a general purpose circuit simulator. It performs nonlinear
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dc and transient analyses, fourier analysis, and ac analysis
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linearized at an operating point. It is fully interactive and
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command driven. It can also be run in batch mode or as a server.
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The output is produced as it simulates. Spice compatible models
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for the MOSFET (level 1 and 2) and diode are included in this
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release.
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Since it is fully interactive, it is possible to make changes and
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re-simulate quickly. The interactive design makes it well suited
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to the typical iterative design process used it optimizing a circuit
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design. It is also well suited to undergraduate teaching where
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Spice in batch mode can be quite intimidating. This version, while
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still officially in beta test, should be stable enough for basic
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undergraduate teaching and courses in MOS design, but not for
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bipolar design.
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In batch mode it is mostly Spice compatible, so it is often possible
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to use the same file for both ACS and Spice.
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The analog simulation is based on traditional nodal analysis with
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iteration by Newton's method and LU decomposition. An event queue
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and incremental matrix update speed up the solution for large
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circuits.
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It also has digital devices for mixed signal simulation. The
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digital devices may be implemented as either analog subcircuits or
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as true digital models. The simulator will automatically determine
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which to use. Networks of digital devices are simulated as digital,
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with no conversions to analog between gates. This results in
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digital circuits being simulated faster than on a typical analog
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simulator, even with behavioral models. The digital mode is
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experimental and needs work. There will be substantial improvements
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in future releases.
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ACS also has a simple behavioral modeling language that allows
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simple behavioral descriptions of most components including capacitors
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and inductors. Unfortunately, it is not well documented.
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ACS uses an object oriented approach to modeling. Complex models
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like MOSFETS are made of simpler ones like resistors, capacitors,
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diodes, and any other models that may already exist. The model
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designer does not need to worry about details like convergence
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checking, bypass checking, integration, or how the new device plugs
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into the solution matrix because these are already taken care of
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by the basic models. This results in a dramatic improvement in
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the time it takes a researcher or model designer to install a new
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model, compared to Spice.
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