61 ACS, a general purpose mixed analog and digital circuit simulator

(from comp.lsi.cad)

A new version of ACS (Al's Circuit Simulator) has been posted to alt.sources. It is also available by ftp from ftp://cs.rit.edu/pub/acs or ftp://ee.rochester.edu/pub/acs . If you don't have net access you can get it by dial-up from (USA) 716-272-1645.

ACS is a general purpose mixed analog and digital circuit simulator. It performs nonlinear dc and transient analyses, fourier analysis, and ac analysis linearized at an operating point. At this point the analog is stronger than the digital. (In fact, the digital part is rather weak.) It is fully interactive and command driven. It can also be run in batch mode or as a server. The output is produced as it simulates. Spice compatible models for the MOSFET (level 1 and 2) and diode are included in this release.

This version (0.13) includes several improvements including real Fourier analysis and better time step control based on truncation error. There are other minor improvements.

Since it is fully interactive, it is possible to make changes and re-simulate quickly. The interactive design makes it well suited to the typical iterative design process used it optimizing a circuit design. It is also well suited to undergraduate teaching where Spice in batch mode can be quite intimidating. This version, while still officially in beta test, should be stable enough for basic undergraduate teaching and courses in MOS design, but not for bipolar design.

In batch mode it is mostly Spice compatible, so it is often possible to use the same file for both ACS and Spice.

The analog simulation is based on traditional nodal analysis with iteration by Newton's method and LU decomposition. An event queue and incremental matrix update speed up the solution for large circuits.

It also has digital devices for true mixed mode simulation. The digital devices may be implemented as either analog subcircuits or as true digital models. The simulator will automatically determine which to use. Networks of digital devices are simulated as digital, with no conversions to analog between gates. This results in digital circuits being simulated faster than on a typical analog simulator, even with behavioral models. The digital mode is experimental and needs work. There will be substantial improvements in future releases.

The source and documentation can be obtained by anonymous ftp from ftp://ee.rochester.edu/pub/acs or ftp://cs.rit.edu/pub/acs . It can also be obtained by dial-up (USA) 716-272-1645 in /pub/acs. It may be distributed under the terms of the GNU general public license. The dial-up also has some test circuits, pre-compiled executables for Next, Sun4, MSDOS and possibly others, and documentation in dvi and postscript.

This document was translated by ms2html v1.7 on 16.01.97. OMN

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