Chapter B, Problem 31E

Explanation of Solution

The above diagram describes about the 4 bit carry look ahead adder that includes 3 gate delays for all carry bits and 4 gate delays for all sum bits.

Here, the time unit is denoted by T.

The time taken to generate P_i and G_i is 1T.

The time required by all the carries C_i is 2T.

The time required for generating the sums S_i is 2T.

By comparing from the above statements,

For time T=0, $\text{T}\text{=}\text{0}\text{A3}\mathrm{..}\text{0}\text{B3}\mathrm{..}\text{0}\text{C0}$

For time T=1, $\text{T}\text{=}\text{1}\text{G3}\mathrm{..}\text{0}\text{g3}\mathrm{.}$