[SI-LIST] : QUAD Model & Device capacitance

Mark Nass (markn@rccorp.com)
Tue, 14 Apr 1998 14:30:49 -0700

I have a question about the value of CEFF: in a QUAD model
I was given the diagram of an output buffer we are using, see diagram
below, and I am confused on what value I should use for device capacitance.
My feeling is that the 1.7pf, 2.2pf & 1.6pf are "embedded" in the Rise/Fall
times & VI curves because the QUAD model data was generated from HSPICE
models.
This would mean that I would need to add the 3.0pf and 3.1pF to get a total
device capacitance of 6.1pF, and this would be the value in my SHUNT
statement.
Any QUAD experts out there with an answer or opinion?

Thanks,
Mark Nass

Power
_|
| | Power
-------| | |
| |_ |
1.7pf > | ___|___ ------
Junction | | | | |
|--------| |________| | 3.1pf Metal
2.2pf | ^ ^ | |
Junction >| 1.6pF 3.0pF ------
| | Junction Junction
-------| |
| |_
|
|
|
GND