[SI-LIST] Re: Substrate board impedance added to driver impedance for total output impedance of driver

Eric-

            +------+
--R--L--+---|      |
        |   | Z    |
        C   |driver|
        |   |      |
--------+---|      |
            +------+


Assuming your RLC package parasitics and Zdriver are connected as in the =
above diagram, vectorially calculate the parallel combo of Zc and =
Zdriver and then add that value (vectorially) to the vector sum of Zr + =
Zl. Or put the circuit into spice and let it do the number cunching for =
you.


Zinput =3D Zr + Zl +(Zc // Zdriver)



-Ray


Raymond Anderson
Senior Signal Integrity Staff Engineer
Product Technology Department
Advanced Package R&D
Xilinx Inc.
=20


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of Eric Steimle
Sent: Thursday, June 30, 2005 7:59 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Substrate board impedance added to driver impedance =
for total output impedance of driver

I'm have a chip that I've done some analysis on to get its driver
impedance.  However this chip is on a substrate board, and it's drivers
run through traces to balls and to the board.  I have R, L, and C
numbers for the trace/bondwire combination as part of a package model
that was made by someone else.  The trace in question is =BD inch long =
and
the frequency of interest is 350Mhz.  I've made the assumption that I
can use vector addition to add the inductive and resistive contributions
together, but I don't know what to do with the capacitive part.  I'm
also assuming that once I've vector added the inductive, resistive, and
capacitive parts together for a total Zpackage that I can then linearly
add Zpackage and the Zdriver from previous experiments.  Does that seem
right?  I'm just a little confused on the appropriate steps to take.  As
always I appreciate the time you all take to read and respond to my
questions.
=20

Thanks,

=20

Eric Steimle

=20


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