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Dear D. C.
Do you mean 40uH/inch? or 40nH/inch?
Best Regards
Weber Chuang(ChingFu Chuang)
SI Engineer, System Team.
VIA Technologies, Inc.
Taipei, Taiwan, ROC
*************************************************
> Re: [SI-LIST] : Modeling Package parasitics
> Mark Nass wrote:
> >
> > Does anybody have an accurate way of modeling package parasitics,
> > in particular in a QUAD simulation environment. I have been using
> > a lumped inductance for a BGA & SQFP package but find this to be
> very
> > inaccurate with fast edge rates and small voltage level swings. The
> ringing
> > from the inductor causes the signal to cross switching thresholds in
> the
> > simulation environment, but this ringing is not seen on the lab
> bench.
> > My feeling is that a specified ZO, TPD & and Length should be
> used
> > for the bonding wire, trace on the BGA package and the pin.
> > Does anybody have any thoughts on what values I could use for
> > the bonding wire?
>
> Bondwires are actually very good inductors. The package itself
> may be a PWB in implementation (consider BGAs). A good figure
> for bondwire inductance is 40uH/in.
>
> One of the reasons that many simulations show excessive ringing
> on ICs is that the capacitors are too high-Q. Most semiconductor
> capacitances (such as the ESD structures on I/O circuits) have
> quite large ESRs. Your best bet would be to correlate the ESR
> to the lab data.
>
> --
> D. C. Sessions
> [email protected]
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