ibis calculation -understanding I-V curves

[ankitgarg0312]

ibis calculation

i have a output buffer ibis model, if i use a 1v pulse at input i gets a 3v output but if i applies a 0.5 v output i gets 0v output

as per my understanding I-V curves are calculated from output node wrt tovdd/gnd

from which part of ibis mdels is this dependence on input voltage coming?
also from where is this 3v level arriving? voltage levels specified in ibis are 5v for typ

 

[marikundam]

ibis calculation

Hi
Can you show the test bench diagram explaining in brief about the setup?

 

[tom_hanks]

Re: ibis calculation

Can you upload the file..
I think I can help you on this..

Tom

 

[ankitgarg0312]

Re: ibis calculation

i am uploading ibis file i used,
please tell me which portion of ibis file is determining output and input voltage relationship

 

[tom_hanks]

Re: ibis calculation

>if i use a 1v pulse at input i gets a 3v output but if i applies a 0.5 v output i gets 0v output
Ans: this model is not a functional base model. you cannot apply input and check output..

IBIS model is to check the In and out V/I charactierictic depedps upon load.

AT16245 input model: Vinl = 0.8V & Vinh = 2.0V.
In practicle (on chip),if input is 1v then ouput will be x,z or last logic..this depends upon the fabrication technology on chip.

can I know which simulation tool, you are using with this model.


>as per my understanding I-V curves are calculated from output node wrt tovdd/gnd
Ans: no..
output is based on Pulldown /pullup rating(which calculated by manufacture based on IC technology used)

>from which part of ibis mdels is this dependence on input voltage coming?
Ans:there is no relation in IBISI model betwee input and output..

>also from where is this 3v level arriving? voltage levels specified in ibis are 5v for typ
Ans:
If you see the Risiing and falling waveform table of the bufffer..
then you will see that buffer is going high(5v) for only 4ns and then after it is settled at 3v.
This characterisitics is a result of buffer model test and we use this result for simulation.

similarly, if you check the falling waveform, then reading are starting from 3v and not from 5v. this buffer

model is not tested wrt to 5v by manafacturer.
(so you cannt do any thing to get the 5v reading)

Tom
if you need any further help, try logicdevv_co_uk