how can i get ibis model for following components
With regards the ADG918, sorry but currenlty there is no IBIS model availble.
I don't believe that we have IBIS models for any of these components. If we do, they will be on the web.
I attached a the IBIS model of the AD9864 which is the same product as the AD9874 with the exception that its LNA/mixer bias level is fixed (vs programmable as AD9874). While AD9874 is is LQPF (vs LFCSP for AD9864), the pinout/package dimensions are the same (except leaded vs leadless) hence I do not any significant difference in the model parasitics for pins (R-L-C).