[IBIS] RE: [IBIS-Users] hspice vs IBIS model correlation at different capacitive loads

Venu,
 
How long is the transmission line you're using ... about 1ns?
 
Your IBIS driver in the 30pf case seems to be taking several round-trips
to charge the load where the HSpice driver doesn't - if this is a
programmable driver, is it possible the driver settings for the two
plots are different?  In the top plot for the 30pf case, the IBIS driver
looks like a much weaker output with a faster slew rate to me ...
 
Todd.

Todd Westerhoff
High Speed Design Group Manager
Cisco Systems
1414 Massachusetts Ave
Boxboro, MA 01719
email:twesterh@cisco.com
ph: 978-936-2149
____________________________________________
"Always do right.
 This will gratify some people and astonish the rest."
 
- Mark Twain

 

________________________________

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On
Behalf Of Ummalaneni, Venu Babu (Venu)
Sent: Tuesday, December 13, 2005 5:38 AM
To: ibis-users@eda.org; ibis@eda.org
Subject: [IBIS-Users] hspice vs IBIS model correlation at different
capacitive loads



Hi Gurus,

I have an ATA* IBIS model and it is correlating well with hspice model
when I am using a 5pF load followed by a transmission line. If I replace
the 5pF load with 30pF correlation is bad (particularly in 2nd page
waveform of attached PDF). 

Could some one comment on this, where it is going wrong?

Your comments/inputs are highly appreciated.

Attachments: ata4nik_5pf.pdf - hspice and IBIS model waveforms captured
using 5pF load

                    ata4nik_30pf.pdf - hspice and IBIS model waveforms
captured using 30pF load

Thanks & Best Regards,

Venu

<<ata4n1k_30pf.pdf>> <<ata4n1k_5pf.pdf>> 


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