The George Washington UniversitySchool of Engineering and Applied Science

Department of Electrical and Computer Engineering

ECE122 – Lab 3Multiplexers, Parity Generators and other

Boolean functions using MUX

Ritu BajpaiOctober 9, 2008

Multiplexers (Review)

● A multiplexer has n select lines, 2n inputs and 1 output.

● The number represented by the select lines chooses one of the inputs to be placed on the output.

4X1 Multiplexer

X1 X2 X3 X4 S1 S2 O

A B C D 0 0 A

A B C D 0 1 B

A B C D 1 0 C

A B C D 1 1 D

X1

X2

X3

X4

S1 S2

O

Homework from last lab...

You were supposed to ● Review a 2x1 multiplexer.● Review 4x1 multiplexer from your 2x1

multiplexer.

Application of multiplexers

● Now we are ready to learn the application of multiplexers to make useful circuits like parity generator and adder.

Parity Generator (Lab Exercise)

● Build a circuit that determines if the number of inputs that are high is even or odd.

● 3-bits using a 4x1 multiplexer.● Simulate your circuit.

Results and Analysis

● Test your parity generator for all possible combinations of 3 bit input.

● Show the output waveforms for the above test in your lab report.

● What is the application of a parity generator?

Homework

● Implement a 1-Bit full adder using a 4x1 multiplexer.

● Simulate your adder.● You should test your circuit for all

possible combinations of input.