RE: output impedance of a driver

Jason,

The DC impedance can be found by dividing V/I on the IV curve of
the buffer. You will find that you get a different value at
practically any of the voltages due to the non linear shape of
the IV curve. Plus, the process variation of a chip can give
you a variation on the order of 2-3x. So finding the impedance
and matching the T-line to it is like shooting at a moving target.

The reason I said DC impedance above is because the capacitive
components of the buffer will also alter the impedance of the
buffer a higher frequencies.

Arpad Muranyi
Intel Corporation
================================================================

-----Original Message-----
From: Jason Leung [mailto:jleung@cid.alcatel.com]
Sent: Monday, April 09, 2001 6:14 AM
To: ibis-users@eda.org
Subject: Re: output impedance of a driver

Hi all:
Morning!
I am trying to obtain the output impedance of a driver, so that I can
match the driver with a transmission line and proper termination.
The way that I have tried is I used the IBIS model and then translate
the model into QUAD model, so that I can used the XNS to observe their
rising and falling waveform. Moreover I am trying to find its output
impedance in XNS.
My question is : Does anyone ever try finding the output impedance of a
driver? AND how did you achieve that?

Thanks very much for your comment!
Jason leung

 
Received on Mon Apr 9 07:59:23 2001