[IBIS] 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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