RE: [IBIS] Different PMOS and NMOS driver impedence

Chetana,
 
Rfixture should be chosen according to the
planned transmission line impedance that will
load the buffer, nit the buffer's impedance.
 
Arpad
===============================================

________________________________

From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On
Behalf Of Chetana Raghuwanshi
Sent: Monday, August 18, 2008 8:07 AM
To: ibis-users@server.eda.org; ibis@server.eda.org
Subject: [IBIS] Different PMOS and NMOS driver impedence



Hello Experts,

One of my IO cell has a buffer with different PMOS and NMOS impedences.
PMOS impedence is approx 200 Ohms and that for NMOS is 96 Ohms.
In this case what should be the value of Rfixture for calculating IV VT
curves ?
Would it be Rfixture1 for calculating pull down and falling waveforms
and Rfixture2 for calculating pull up and rising waveforms ?
If I do rise/pullup and fall/pulldown simulations with different
Rfixture values, is it acceptable ?

Best Regards
Chetana


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