Subject: RE: [IBIS] Terminated buffer
From: Shee Kian Wong (SKWONG@altera.com)
Date: Thu Oct 10 2002 - 16:39:53 PDT
Hi all,
Normally we would use a 50ohms resistor and connect it to the output node to
get rising/falling data. However, if the built-in resistor is 50 ohms, and
we connect the IBIS load resistor (another 50ohms) to vcc, are we not going
to get an effective resistance that is lower that 50 ohms?
Confused,
Shee Kian
-----Original Message-----
From: Ingraham, Andrew [mailto:Andrew.Ingraham@hp.com]
Sent: Thursday, October 10, 2002 8:39 PM
To: Shee Kian Wong
Cc: ibis@eda.org
Subject: RE: [IBIS] Terminated buffer
The Pullup and/or Pulldown clamp I-V curves should describe anything that is
always in the circuit, including leakage currents, terminations, etc.
If the termination is independent of the supply, put it into the Pulldown
curve. If it tracks with the supply, use the Pullup curve, or a combination
of both.
Regards,
Andy
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