Re: [IBIS-Users] problems about extracting IV curves from SPICE model

> For my circuit connection, let's take pulldown curve as an example, I give
> corresponding Vdd voltage source to power suply, ground input and connect
> the output to a variable voltage source (V1) and use a current probe to
> measure the output current(I1) at the output port. I plot the IV curve I1
> vs. V1 and treat it as the pulldown curve. No floating voltage source in
> the circuit.
> Can anyone tell me what's wrong with my connection?

Yuancheng,

Other than the fact that the 74lvc04a is an inverter, so grounding the input
drives the output high (pullup not pulldown ... I'm thinking it was a typo),
your connections seem about right.

Did you do this as a .DC sweep, or a slow transient simulation?

The LVC part has a very wide supply voltage range. Did you use a supply
voltage consistent with the IBIS table you compared it to?

How well does both your simulated data, and the IBIS data, compare with the
part's DC specifications for Voh and Vol?

Regards,
Andy

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