Re: [SI-LIST] : Vocabulary of Signal Integrity Degradations

Bill Dempsey (bdempsey@dnaent.com)
Mon, 04 Jan 1999 10:20:22 -0800

Abe Riazi wrote:

> Dear All,
>
> During the course of a signal integrity simulation, there are an
> infinite number of different waveform patterns which can emerge. One
> of
> the responsibilities of a SI engineer is to provide meaning to these
> waveforms and to evaluate their implications. To accomplish these
> objectives, it is often necessary to recognize several critical
> waveform
> characteristics (or signal integrity degradations), as defined below:
>
>
> OVERSHOOT (The initial transient response which exceeds the steady
> state
> response).
>
>
> UNDERSHOOT (Excessive voltage pulse below ground. Also called negative
>
> overshoot)

I would not mix the use of overshoot and undershoot to mean the same
thing *only different*. Overshoot, both positive and negative variants,
exceed the steady state response. One is more positive than the desired
result and one is more negative. This leaves the definition of
undershoot clear since there is a case when the desired positive voltage
is not acheived (likewise the negative). Undershoot has its place -- as
does overshoot.

I would suggest in an open forum that engineers use the classical
definitions and not the defacto (and wrong) definitions.

> Best Regrads,
>
> Abe Riazi

That's my two cents worth.

Bill Dempsey

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