acs (Al's Circuit Simulator) from Thomas Gellekum <thomas@ghpc8.ihf.rwth-aachen.de>

Submitted by:	thomas

1 files changed, 48 insertions, 0 deletions

diff --git a/cad/acs/pkg-descr b/cad/acs/pkg-descr
new file mode 100644
index 000000000000..efc0bfdaf161
--- /dev/null
+++ b/cad/acs/pkg-descr
@@ -0,0 +1,48 @@
+ACS is a general purpose circuit simulator.  It performs nonlinear
+dc and transient analyses, fourier analysis, and ac analysis
+linearized at an operating point.  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.
+
+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 mixed signal 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.
+
+ACS also has a simple behavioral modeling language that allows
+simple behavioral descriptions of most components including capacitors
+and inductors.  Unfortunately, it is not well documented.
+
+ACS uses an object oriented approach to modeling.  Complex models
+like MOSFETS are made of simpler ones like resistors, capacitors,
+diodes, and any other models that may already exist.  The model
+designer does not need to worry about details like convergence
+checking, bypass checking, integration, or how the new device plugs
+into the solution matrix because these are already taken care of
+by the basic models.  This results in a dramatic improvement in
+the time it takes a researcher or model designer to install a new
+model, compared to Spice.