i am designing a multiplier circuit which uses a adder. what is the
fast adder with less delays.

This seems to be an active area of research. The definitive answer may
not be known at this time. Also, you do not specify how many bits wide
you need the adder to be, or whether there is any limit on the
complexity of the adder. If you can provide more information, or
clarify what would constitute a sufficient answer, I may be able to
help more.

hi 
i am Designing 8x8 multiplier using modified booth algorithm and like
to extend it to 16x16 bit. the process i am using is Slef Reseting
CMOS (SRCMOS). until now i designed upto partial products stage, next
stage is adding those partial products to get the final output. i need
 a faster adder so that it adds all those partial products to give my
final output.
hope i am clear my slef.
let me know if you need any more details.
thanks
praveen