[SI-LIST] : Fwd: Connector question on SI

John Fisher ([email protected])
Fri, 13 Nov 1998 17:15:34 -0800

>X-SMAP-Received-From: outside
>From: "Cutler, Robert" <[email protected]>
>To: [email protected]
>Cc: [email protected]
>Subject: Connector question on SI
>Date: Fri, 13 Nov 1998 17:14:13 -0500
>X-Mailer: Internet Mail Service (5.5.2232.9)
>John Fisher at Cisco passed on your question about routing differential
>pairs through the connector. There are a number of issues to be considered.
>The frequency and edge speed of the differential signals is critical to the
>way the connector is implemented. Open pin field connectors can be used at
>gigabit speeds if the differential pairs are well isolated from each other
>with grounds. The ground pins also serve to help control the differential
>impedance through the connector. For example, in the 2mm Hard Metric
>connector, differential pairs will be ~ 100 ohms when surrounded with
>grounds. The exact pinout will be a function of the specific connector
>chosen and the isolation required.
>There are also controlled impedance connectors which include internal ground
>shields. No additional ground pins are required. AMP makes a controlled
>impedance backplane connector with either 6 rows or 10 rows. The
>differential impedance is near 100 ohms and the noise performance is
>excellent. This is the HS3 connector family.
>Feel free to call me if you want to talk in more detail.
>Have a good weekend.
>Robert Cutler
>Consultant to AMP Inc.
>(310) 456-5325
>FAX (310) 456-2566
>[email protected]

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