UPC EETAC Bachelor's Degree in Telecommunications Systems and in Network Engineering EEL

Chapter 1 problems

      - A1.2 -

Circuits using only-NAND or only-NOR gates




1. Specifications

Given the following Boolean expression:


a) Draw the circuit's symbol and truth table. Represent the circuit using only NAND logic gates.

b) Express the output as a sum of minterms and a product of maxterms.

c) With the equation obtained in b), represent the circuit using only-NOR logic gates.

d) Calculate the maximum frequency of operation of this circuit if the propagation delay time tPHL and tPLH of a gate of this kind, for instance 74HCT technology is 21 ns.

e) How would you use the VHDL simulator to verify the truth table of this digital circuit?

The representation in Fig. 1 is a map that can help to comprehend the concepts. Once you have deduced the circuit's truth table, you can produce several circuits that meet the same specifications.


Fig. 1. Concept map to explain the idea of extracting several circuits from the same initial specifications.