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

Abe Riazi (ariazi@anigma.com)
Mon, 4 Jan 1999 13:27:12 -0800

Hi:

The definitions which I had presented in my email had been collected
from several sources including technical dictionaries, high speed
digital design books, and signal integrity manuals.

I received several emails which indicated disagreement with the
definition given for the term UNDERSHOOT and provided alternative (and
more comprehensive) definition for that term.

I am thankful for these comments.

Regards,

Abe Riazi

>----------
>From: Bill Dempsey[SMTP:bdempsey@dnaent.com]
>Sent: Monday, January 04, 1999 10:20 AM
>To: Abe Riazi
>Cc: 'si-list@silab.eng.sun.com'
>Subject: Re: [SI-LIST] : Vocabulary of Signal Integrity Degradations
>
>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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