RE: [SI-LIST] : IBIS question regards [Falling Waveform] / [Risin g Waveform].

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From: Peters, Stephen (
Date: Tue Apr 11 2000 - 15:13:42 PDT

Merav wrote:

> My question regards: [Falling Waveform] / [Rising Waveform].
> Our I/O buffer, output stage, contains the following structure:
> <<...>>
> while performing a rising transient on the pad , the ndrv signal
> "brakes" before the pdrv "mates".
> This cause a strange wave on the pad while simulating a [Rising
> Waveform] with R_fixture (resistor) connected to Vcc:
> The PAD begin to rise and even get to almost full swing
> before the Pmos opens. This cause a steepest slope of the [Rising
> Waveform] while simulating R_fixture connected to ground rather than
> R_fixture connected to Vcc .
> Waves forms:
> <<...>>
> Is this kind of wave is "harmful" to the IBIS model users?
> should I omit
> it,
> and leave only the [Rising Waveform] with resistor connected
> to ground ?
> Thanks,
> Merav.

No, you should not. In fact, the kind of behavior you describe is exactly
what the four waveform method shown in the IBIS cookbook

is designed to show. Please refer to the cookbook for more details.

  Stephen Peters
  Intel Corp.

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