Different parts have different timing test loads associated with them. They are specified by the manufacturer and usually included in the datasheet. If the timing test load is just a capacitor, Cref then the model should have that in it. If the timing test load is a transmission line terminated in its characteristic impedance to a voltage then you should put the Rref resistance Ro to the termination Vref the termination voltage. IBIS has no way of describing a transmission line in the timing test load. Tom Dagostino Teraspeed Labs 13610 SW Harness Lane Beaverton, OR 97008 503-430-1065 http://www.teraspeed.com tom@teraspeed.com Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 401-284-1827 Teraspeed is the registered service mark of Teraspeed Consulting Group LLC -----Original Message----- From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On Behalf Of RODRIGUEZ_LECONA_RAMIRO Sent: Thursday, April 14, 2005 2:53 PM To: ibis-info@eda.org; ibis-users@eda.org Subject: [IBIS-Users] question about Cref Hi all, In some cases the semiconductor vendors use a transmission line terminated with a 50 ohms resistor to Vdd/2 in order to determine the propagation delay or switching time of the devices. If the IBIS standard says I have to specify Cref and the IBIS user wants to perform a timing analysis, then, is it necessary to specify Cref? Regards, Ramiro. |------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993 |------------------------------------------------------------------ |For help or to subscribe/unsubscribe, email majordomo@eda.org |with just the appropriate command message(s) in the body: | | help | subscribe ibis <optional e-mail address, if different> | subscribe ibis-users <optional e-mail address, if different> | unsubscribe ibis <optional e-mail address, if different> | unsubscribe ibis-users <optional e-mail address, if different> | |or email a written request to ibis-request@eda.org. | |IBIS reflector archives exist under: | | http://www.eda.org/pub/ibis/email_archive/ Recent | http://www.eda.org/pub/ibis/users_archive/ Recent | http://www.eda.org/pub/ibis/email/ E-mail since 1993Received on Thu Apr 14 15:05:39 2005
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