[IBIS-Users] IBIS model for a slow slew rate output driver question

Hello All,

My name is Anshul Bansal and I am trying to create an IBIS model for an 
output driver that has the same drive strength but some config bits that 
can select different output slew rate settings. The fast setting for 
output driver has a slew rate in order of 5ns whereas the slow setting 
has a slew rate of 30-50ns.

I have been able to successfully generate the IBIS model using the 
conventional method for rising and falling waveforms i.e. 50ohm 
termination resistor to ground and vcc_io. However when I try to run 
some co-relation simulations on the IBIS model and compare the results 
with the actual circuit, I can get very good co-relation (within 5-10% 
of actual circuit) for the fast setting of the output driver (waveform 
attached in fast.pdf). However the co-relation for slow setting of 
output driver is about 40-50% off as compared to actual circuit 
simulations (waveform attached in slow.pdf).

I was wondering if there are other techniques that I should be using to 
model this slow setting for the output driver in the IBIS model, instead 
of the conventional settings like changing the Vfixture or Rfixture. Can 
anyone tell me how are such models captured by other engineers?

Any response to these questions are highly welcome.

Thanks,

Anshul

-- 
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

--------------------------------------------------------------------
|For help or to subscribe/unsubscribe, e-mail majordomo@eda-stds.org
|with the appropriate command message(s) in the body:
|
|  help
|  subscribe   ibis       <optional e-mail address, if different>
|  subscribe   ibis-users <optional e-mail address, if different>
|  unsubscribe ibis       <optional e-mail address, if different>
|  unsubscribe ibis-users <optional e-mail address, if different>
|
|or e-mail a request to ibis-request@eda-stds.org.
|
|IBIS reflector archives exist under:
|
|  http://www.eda-stds.org/pub/ibis/email_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/users_archive/ Recent
|  http://www.eda-stds.org/pub/ibis/email/         E-mail since 1993