Maximum propagation delay


#1

Assume that a half adder has a maximum propagation delay of ∆, and a full adder
has a maximum propagation delay of 2∆. What is the maximum propagation delay for your
4-bit adder, from LSB input to MSB output?


#2

As we know
we have three (3) full -adders and one half adders in your 4-bit adder design ,
so the maximum propagation delay for 4-bit adder from the L S B input at the half-adder to the MSB output at the last full adder must go through all the adder components.
Therefore the maximum propagation delay is :-
3 * 2 delta + delta =7 delta