# Pulse Width Modulation

## Pulse Width Modulation

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ANTENNA ENGINEERING

BETT 4833

SEMESTER 1

SESI 2015/2016

LAB 1: Pulse Width Modulator

NAME OF GROUP MEMBERS &
MATRIX NUMBER
1. CHAN WEI NICK
B071210113

2. SARAVANAN A/L SUKUMARAN
B071210044
COURSE
4 BETT
DATE
10/1/2015

NAME OF INSTRUCTOR
MOHD ERDI BIN AYOB

EXAMINER’S COMMENT

VERIFICATION STAMP

TOTAL MARKS

OBJECTIVES
To implement the pulse width modulator by using µ741.
To measure and analyse the pulse width modulation circuit.

EQUIPMENT
TC-6000-02-DCT3 Trainer

EXPERIMENT RESULT

Input Signals
Input and Output Signal Waveform
Sinusoidal Wave

Square Wave

Triangle Wave

Table 1: The input and output signal waveform of sinusoidal, square and triangle wave.

QUESTION

1. What are the functions of VR1?
VR1 is a variable resistor used to adjust the input terminal Vin(+) operation voltage. When we adjust VR1, then the Vin(+) input terminal operation voltage will change, which means the reference voltage comparator will change, thus the output signal of pulse width will also change too. If the VR1 is fixed, it means that the operation voltage of Vin(+) input terminal is fixed.

DISCUSSION
In this experiment, three different waveforms, the sinusoidal, square, and triangular waveforms are used as an input signal to investigate the properties of pulse width modulation (PWM).

With that said, it is found that the output of the PWM signal is always at a peak of positive 5 volts and negative 5 volts. This is most probably due to the design of the PWM trainer itself, where the output signal is filtered at VR1 so that the output is always constant at 5 volts and negative 5 volts. This assumption is verified by the function of VR1, whereby adjusting the variable resistor VR1 will change the reference voltage of...