Question

1. Assume all the gates in Figure 3-18 have a propagation delay of 1 nsec, and all other delays can be ignored. How much time does it takes the AND function to produce a result? How much time does it takes the OR function to produce a result? How much time does it takes the NOT function to produce a result? How much time does it takes the ADDER function to produce a result?

Logical unit Carry in AB INVA A ENA AB -Output ENB Sum Enable lines Fo Full adder F1 Decoder Cam out

Answer 1

Solution:

Calculation for the critical path

"Calculation for the critical path NOT gate Number of gates in critical path = 2 Time required = 2 times 1 n s = 2 n s OR gate Number of gates in critical path = 6 Time required = 6 times 1 n s = 6 n s AND gate Number or gate in critical path = 3 Time required = 3 times 1 n s = 3 n s The complete result of Adder depends on "" Output "" and "" carry out "" pin . The maximum time required in between "" output "" and "" carry out "" pin is the actual time required by the ADDER "" output "" . Number gates in critical path = 6 Time required = 6 times 1 n s = 6 n s "" carry out "" Number of gates in critical path = 5 Time required = 5 times 1 n s = 5 n s the generation "