a 16-bit adder is to be designed using four 4-bit carry-lookahead adders:
(a) draw and label your design using ripple-carry connections between the four carry-lookahead units.
(b) modify your design to eliminate the ripple carry from part (a) above using an additional level of carry-lookahead logic. Label all inputs and outputs.
(c) calculate the total delay time (in terms of number of gates) for each of (a) and (b) above.