Thanks! for your info.
I have referred the datasheet earlier itself it states clearly, there will be option for LVTTL/LVCMOS 1.8 V in page No 10.
But i have to do Signal integrity analysis for the same signals using the Cyclone3 IBIS models. In that LVCMOS 1.8V model selector was not available. Only LVTTL models are present.I got confused over here.
So, what can be considered for SI simulations. kindly provide your suggestion.
Vilas Kumar S