What determines Vref & Rref, R_fixture & V_fixture?

I'm starting to use s2ibis2 to create models
for a gate array library. I don't understand
the significance of the Rref and Vref sub-parameters
under [Model]. We characterize propagation delays
for the I/O buffers in SPICE for a range of
capacitive loads on the output pad. It isn't
clear what values to use for Rref and Vref
(or Cref for that matter).

Similarly, how do I determine the values to
use for R_fixture and V_fixture with
[Rising Waveform] and [Falling Waveform]?

-Greg Haynes
UTMC
 
Received on Wed Feb 23 10:59:12 2000