Subject: Re: [IBIS-Users] IBIS model driver impedance
From: Scott McMorrow (scott@teraspeed.com)
Date: Fri Jan 10 2003 - 00:51:52 PST
From ohms law
V=IR
therefore
R =V/I
In the ibis model is a V/I table.
The impedance is real, thus at any point in the table the impedance is:
Z = V/I
As you will see, the impedance will change depending upon the output
voltage. If you want to find a good average impedance, then find the
current at approximately half of the voltage swing of the driver. You
can compute this for the pullup and the pulldown curves at all three
corners.
best regards,
scott
-- Scott McMorrow Teraspeed Consulting Group LLC 2926 SE Yamhill St. Portland, OR 97214 (503) 239-5536 http://www.teraspeed.comShee Kian Wong wrote:
> Hi all, > > > > Can anyone suggest a way to measure the driver impedance of an IBIS > buffer? Do the look-up tables in the IBIS file carry this information? > > > > Regards, > > SK >
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