Re: BIRD 42.3

Richard A. Schumacher wrote:
>
> In other words, different applications require different
> device models. Even one given circuit will require
> different models depending, as in the example, on whether
> the time between output transitions is greater than or less
> than the settling time. True?

That's one way. (For those joining late: Mr. Schumacher refers
to the problem where an output is still sourcing current into
an unsettled line when it switches LOW. The pullup turnoff
will produce one output step, followed some time later by the
pulldown turnon step.)

Far more serious, I would tink, is the situation in terminated
lines (eg, SSTL) where the line NEVER quiesces to a zero-current
state. For a whole lot of reasons, the output will almost
always do a two-step: first to the OFF state and then to the
reverse state. The difference between this and the academic
smooth-transition model is pretty significant.

-- 
D. C. Sessions
dc.sessions@tempe.vlsi.com