Re: Rev 2.0 items for discussion

IBIS-onians,

Stephen Peters writes:

>> Also under discussion is how to best handle packages whose bond wires/
>> lead frames are long enough to be considered transmission lines. It
>> has been proposed to distribute the L and C values. My questions is,
>> does the current spec contain all the information needed or is there
>> something else to add.

    L & C are fine so long as it's just a single transmission line.

    It seems to me that if we want to go to this level of detail,
    using transmission line models for the package, we should also
    probably be considering the discontinuities that occur as
    a signal travels from bond wire to lead frame to package pin.
    These could give rise to reflections, etc. that can't be
    modeled by a single uniform line. A really rigorous model
    would have a separate transmission line model for each piece.

>> If there is anything I have missed please email the IBIS forum.

    Crosstalk/noise due to the package: eventually we're going to
    need to address the mutual inductances/capacitance couplings
    between pins, lead frame wires and bond wires. This data
    may be unavailable from some Si vendors, and the tool vendors
    might be unable to use it immediately, but shouldn't we
    anticipate this need in the Version 2.0 spec? Eventually the
    customers will be demanding crosstalk/ground bounce analyses...

Have a pleasant day,

Eric Bracken
Performance Signal Integrity, Inc.
Received on Wed Sep 8 12:57:57 1993