Gnucap 0.32 release notes  (09/30/2002)

New features:

1. Series resistance in the diode.  It took 5 minutes to do,
so it is embarrasing that it wasn't done before.

2. History and command line editing, using Gnu Readline.  Thanks to
Simon Hoffe for sending me the patch.

3. More parameters in the BJT model.  This gives it better
compatibility with commercial simulators.  These parameters are beyond
Spice 3f5.

4. "M" parameter in diode, BJT and MOS devices.  M is the number of
parallel devices.  Some commercial simulators have this.



Changes that may or may not be improvements.

1. The definition of the transient option "UIC" has changed.  It is
now Spice compatible, which means to not attempt to do any solution or
consistency check.  Just apply the values, assuming anything that
isn't specified is 0.  The old behavior was to attempt a solution
while holding the IC values.
 

Bug fixes:

1. voltage sync bug.  It still doesn't fix the MOS 2 convergence
problem.

2. Fix memory leak in POLY components.

3. Fix bug in Fourier that sometimes causes overrun (crash) and time
sync errors.

4. Modelgen: fix bug in list parsing.

5. Some changes to eliminate warnings when compiling with g++ 3.1.

6. Use Euler differentiation on first step, because trap used a value
that cannot be known then.  Usually, this doesn't make much
difference, but there are a few cases where the error can get
magnified and trigger trapezoidal ringing, leading to a totally bogus
result.  It most cases, you could hide it with small enough steps.
These cases should work with default settings now.

7. Fix bug that sometimes caused incorrect handling of initial
conditions (UIC),

8. Fix bug that caused continuing a transient analysis to give
incorrect results.



Significant internal changes:

1. The inductor uses all of the same support functions as the
capacitor, including "integrate", which is now correctly called
"differentiate".

2. Most of the code is in place for named nodes.  It mostly works and
can be turned on with the option "namednodes".  It is off by default
because it is not complete.  Most likely, it will be finished in the
next release.



Some things that are still partially implemented:

1. BSIM models, charge effects, "alpha0" parameter.  (computed then
ignored)

2. Configure still doesn't handle everything.

3. The model compiler still requires too much raw coding.

4. Named nodes.  If you set the option "namednodes", it will support
named nodes, but some things don't work, so it is off by default.

5. The preliminary IBIS code is now included.  For now, it is a
standalone executable, that reads an IBIS file and generates a
netlist.  The netlist requires some editing to use, and is not fully
compatible anyway.  It is included in hopes of recruiting help in
finishing the project.



Bugs (nothing new, but needs repeating):

1. The transmission line initial conditions are not propagated until
the transient analysis runs.

2. An occasional bogus calculation in MOSFETS occurs when a device is
reversed.  This sometimes causes nonconvergence.

3. The "modify" command with multiple arguments seems to take only the
first one.  It used to work, but is broken in this release.  I am not
sure when it broke.


Hot items for a future release (no promises, but highly probable):

1. Charge effects and substrate current (alpha0) in BSIM models.  They
are computed, but not loaded to the matrix.  It was deferred waiting
for the poly-cap, but now that the poly-cap works, this missing part
of the MOS models should be working soon.

2. JFET model.

3. Completion of multi-rate.

4. Homotopy methods to improve convergence.

5. Transmission line accuracy and speed improvements, using a step
control mechanism similar to that used for capacitors.

6. Parameterized subcircuits and defined parameters.

7. Spice-3 compatible "B" device.


To reach me, try this email address:
	aldavis@gnu.org

ftp sites:
	ftp://ftp.gnu.org/gnu/gnucap/gnucap-0.32.tar.gz
	ftp://ftp.geda.seul.org/pub/geda/dist/gnucap-0.32.tar.gz
	http://www.geda.seul.org/dist/gnucap-0.32.tar.gz
	ftp://sunsite.unc.edu/pub/Linux/apps/circuits/gnucap-0.32.tar.gz
