Spice to IBIS Conversion

Hello Everyone:

This is for those who are interested in the Spice to
IBIS conversion program, S2IBIS2.

I have observed the following difficulty in generating
the V/I curve for an I/O pin. To generate a pull-up or
pull-down curve for an I/O pin when enabled, s2ibis2
creates a voltage source at the enable pin in the .spi
file (say putx.spi for pull-up, typical and pin x as an
example) to make sure that the output is active. That
was done correctly. However, when comes to generate the
pull-up of pull-down curves under disabled condition, no
active voltage source is created in the .spi file (it
will be dutx.spi or ddtx.spi in this case). Anyone who
has tried the tryme.s2i can look at the following two
files, put8.spi and ddt8.spi. In put8.spi, a voltage
source, 'venas2i 61 0 dc 0' was generated to enable the
output. But in dut8.spi, node 61 is left floating.
I tried to correct the problem by connecting a large
resistor from the enable pin to VDD in the .sp file (the
spice source file) to make that pin defaults to high.
It fixed this situation but run into problem in other
cases.

Any feedback or comments from anyone would be very much
appreciated.

Jeff Chu
Digital Equipment Corp.
77 Reed Road
Hudson, MA
01749
(508)568-4197
(508)568-5195 fax
email chu@rock.enet.dec.com
Received on Fri Oct 25 14:58:58 1996