Carry-Lookahead Adders

Carry-lookahead adders also try to speed up addition by addressing the carry bit problem.

Carry-lookahead adders look at blocks at a time and determines if it generates a carry or propagates a carry. It generates a carry if it produces a carry regardless of input ($G_i=A_iB_i$). It propagates a carry if it will return a carry out if it receives a carry in ($P_i=A_i+B_i$).