Re: BIRD #61 -- Characterization of Receivers

All,

> The question is: do you or any of the the other algorithm troglodytes
> have comments on the feasibility of implementing input delay models
> based on the table scheme we presented?

Well, I am concerned that about the use of the new INF reserved word in the
receiver delay table:

> | Use of INF as a Receiver Delay:
> | When building a receiver delay table the user may specify an
> | input condition that does not result in the receiver's output
> | changing state. In that case, the receiver delay is considered
> | infinite, and the reserved word INF is used in the delay
> | column. See the examples below.

> | An example table showing how receiver delay varies vs. overdrive.
> | Note the use of the reserved word INF.
> |
> [Receiver Delay]
> Start_point = 0.8v
> Slope = 1v/1ns
> End_point TABLE
> |variable typ min max
> 1.4 INF 7.0ns INF
> 1.5 INF 5.0ns INF
> 1.51 INF 3.0ns 10.0ns
> 1.53 7.0ns 0.0ns 7.0ns
> 1.55 2.0ns 0.0ns 1.0ns
> 1.6 0.0ns 0.0ns 0.0ns
> 1.7 0.0ns 0.0ns 0.0ns
> 2.0 0.0ns 0.0ns 0.0ns
> 2.1 0.1ns 0.1ns 0.1ns
> 2.5 -0.2ns -0.1ns -0.5ns

Often, interpolation/extrapolation is used when trying to look up values in
tables. When INF appears in the table, doesn't it present a discontinuity in
the data? One of the examples given showed a delay delta of 7.0ns at 1.53V
and INF at 1.51V. What would the delta delay be at 1.52V? Where is the elbow
in the curve? Is this simply a case of the table not having enough data
points?

Regards,
Matthew Flora
IBIS Open Forum Postmaster
(425) 869-2320 PH
(425) 881-1008 FAX
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Received on Wed Aug 18 13:44:22 1999