Re: [SI-LIST] : RE: 2.5 GHz in FR4

About this list Date view Thread view Subject view Author view

From: Bill Owsley (owsley@cisco.com)
Date: Mon Apr 30 2001 - 06:38:22 PDT


At 06:56 AM 04/30/2001 -0400, RMELLISON@aol.com wrote:
>Larry,
>After reading all of the replies to the 2.5GHz questiion, I can see the need
>for using stripline to keep phaseshift constant on long runs. In trying to
>make the stubs a part of the transmission line, wouldn't it be advisable to
>utilise most of the via as part of the line by using the stripline located on
>the opposite side of a card from the IC?
>Consider the 8 layer stackup shown here for clarification.
>
>------- Sig and IC layer
>------------- Plane
>------- Sig
>------------- Plane
>------------- Plane
>------- Sig 2.5 GHz stripline
>------------- Plane
>------ Sig
>
>The stub resulting from the the unused portion of the via is reduced in
>length. The trick would be to make the vias look like the transmission line
>impedance.
>
>Another thought--It seems like an imbedded microstrip line would possess
>almost the same qualities of a stripline in terms of dielectric affecting
>phaseshift. Can a card be made so that the vias would go only from the IC

HDI - High density interconnect. Lasers burn thru to the next layer and
then it's plated to make the connection.

>layer to an imbedded microstrip layer directly below? This would get rid of
>any stubs. What do you think?
>
>Richard Ellison
>972-569-8317

----------------------------
Bill Owsley, owsley@cisco.com
919) 392-8341

Compliance Engineer
Cisco Systems
7025 Kit Creek Road
POB 14987
RTP. NC. 27709

**** To unsubscribe from si-list or si-list-digest: send e-mail to
majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu
****


About this list Date view Thread view Subject view Author view

This archive was generated by hypermail 2b29 : Thu Jun 21 2001 - 10:11:46 PDT