V-AMS Compact Modeling Extensions subcommittee
Minutes of October 8, 2003

Attendees:
Geoffrey Coram, Analog Devices
Ken Kundert, Cadence
Ilya Yusim, Cadence
Jonathan David, Cadence
Colin McAndrew, Motorola
Boris Troyanovsky, Tiburon
Peter Liebmann, Xpedion
Al Davis, Kettering University
Jim Barby, University of Waterloo

1) Model cards
Note that resistor tc1, tc2 can be model or instance param
in many spice-like simulators; there is precedence for
ability of instance to override parameter from model card.

Al talked about his GNUCAP simulator, which introduces yet
another level of parameter: common, which goes between
model and instance.  A circuit that has lots of devices
with the same W and L will share a common and his simulator
will benefit from some further optimization.

It was suggested that we build the idea of paramset, a
syntax for a Verilog-A netlist to handle what a Spice model
card does (and then some); and we should also suggest how
simulators might read a .model card in a standard Spice
netlist and map it to their implementation of paramset.
This would allow maximum use of existing model cards.
The paramset proposal should be on the web shortly, at
http://www.designers-guide.com/private/vams-extensions/compact-modeling/

2) Inheritance
Al asked about the concept of inheritance.  In GNUCAP, he
has a basic mos model that defines the topology (eg, four
terminals), and then the various mos models inherit from
the base class, sometimes through other lower-level models.

Ken suggested that this might be useful for the case that
one takes a standard model like BSIM3 but adds a substrate
resistance.  Using inheritance, an update to the BSIM3
model will be automatically included in the BSIM3_RF model.

One could do this hierarchically (build a module with the
BSIM3 and Rsub in it), but then one has to re-declare all
the BSIM3 parameters for the new module.

3) M factor
Someone noted that the m-factor might not be appropriate
for a system-level module.  If the m-factor is an implicit
parameter to all modules, we might need a way to say that
it is not allowed for some.