Re: [SI-LIST] : Power/Gnd Pin Input Impedance

Dima Smolyansky (dima@easystreet.com)
Tue, 12 Jan 1999 14:29:50 -0800

Christian:

There is quite a number of papers on measurement inductance of the package pins, both from TDR and Network analyzer stand point. However, it seems like the issue here is that people interpreted the question a bit differently,
resulting in quite a bit different interpretation of how this should be measured - and what the model will look like. I think all of them are correct depending on how you look at it, and what exactly people perceive as either
"impedance of the ground pin."

--
Thanks,

-Dima

========================= Dima Smolyansky TDA Systems, Inc. 7465 SW Elmwood St. Portland OR 97223 503-977-3629 503-245-5684 (FAX) dima@tdasystems.com http://www.tdasystems.com

Christian Schuster wrote:

> Hi Eric and Dima, > > may I add a little comment to the input impedance question? > > > Dear SI-List members, > > What is the input impedance looking into IC's Power/Gnd pin? > > How to measure it? > > Thanks. > > > > Eric Chien > > Assistant Researcher > > Synchrotron Radiation Research Center > > Taiwan, R.O.C. > > ycchien@alpha1.srrc.gov.tw > > > I think it should look like a small (I mean: very small) > > inductive value. If the pin is long enough, you should be > > able to observe it with a TDR. > > > > Thanks, > > > > -Dima > > ============================ > > Dima Smolyansky > > TDA Systems, Inc. > > 7465 SW Elmwood St. > > Portland, OR 97223 > > (503) 977-3629 > > (503) 245-5684 (fax) > > dima@tdasystems.com > > http://www.tdasystems.com > > There is a publication in 1994 which exactly addresses this > problem: > > Chi-Taou Tsai, Package Inductance Characterization at High > Frequencies, IEEE Transactions on Components, Packaging and > Manufacturing Technology - Part B, Vol. 17, No. 2, PP 175-181, > May 1994. > > The paper describes a measurement technique based on a vector > network analyser and gives examples as well (120 QFP, 296TAB tape, > 224PGA). It turns out that the impedances of the packages > are described by inductive effects only for low frequencies > (about several nH). At higher frequencies capacitive effects > have to be taken into account as well. In the end even > resonances will show up (of course, these should be well beyond the > working range of frequencies). > > >From own measurements and (FDTD) simulations of bonding wires > I found very similar results. > > Kind regards, > > Ch. Schuster > > ------------------------------------------------------------------- > Christian Schuster, Dipl.-Phys. IIS, ETH Zurich > > Integrated Systems Laboratory > Swiss Federal School of Technology Fax: +41 1 63 21194 > Gloriastrasse 35 Phone: +41 1 63 27595 > CH-8092 Zurich E-Mail: schuster@iis.ee.ethz.ch > Switzerland WWW: http://www.iis.ee.ethz.ch/~schuster/ > ------------------------------------------------------------------- > Note: This mail reflects only my personal experience and/or opinion. > I do not guarantee for any conclusions derived from it. > > **** To unsubscribe from si-list: send e-mail to majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE si-list, for more help, put HELP. si-list archives are accessible at http://www.qsl.net/wb6tpu/si-list ****

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