lab report riphah university

1. Department of Electrical Engineering
Faculty of Engineering & Applied Sciences
Riphah International University, Islamabad, Pakistan
Program: B.Sc. Electrical Engineering Semester: III
Subject EE-241 Basic Electronics Date:
Experiment 10: To obtain common emitter characteristics of NPN transistor
OBJECTIVES:
(i) To obtain common emitter characteristics of NPN transistor
Name : Sap Id :
Performance Lab Report
Description Total
Marks
Marks
Obtained
Description Total
Marks
Marks
Obtained
Ability to
conduct
Experiment
5 Organization/Structure 5
Data Analysis
& Interpretation
5 Calculation & Data
Presentation
5
Total Marks obtained
Remarks (if any): ………………………………….
Name & Signature of faculty: ………………………………….

2. Introduction Of Theory:-
The transistor is a two junction, three terminal semiconductor device which has three
regionsnamely the emitter region, the base region, and the collector region. There
are two types oftransistors. An npn transistor has an n type emitter, a p type base and an n
type collector while a pnptransistor has a p type emitter, an n type base and a p type collector.
The emitter is heavily doped,base region is thin and lightly doped and collector is moderately
doped and is the largest. The current conduction in transistors takes place due to both charge
carriers- that is electrons and holes and hencethey are named Bipolar Junction Transistors (BJT).
We will obtain input characteristics and output characteristics of common emitter (CE)
configuration. We will connect variable DC power supply at VBB and VCC to obtain
characteristics. Input voltage in CE configuration is base-emitter voltage Vbe and input current
is base current Ib. Output voltage in CE configuration is collector to emitter voltage VCE and
output current is collector current Ic. We will use multi-meter to measure these voltages and
currents for different characteristics. Collector to emitter junction is reverse biased and base to
emitter junction is forward biased. The CE configuration is widely used in amplifier circuits
because it provides voltage gain as well as current gain. In CB configuration current gain is less
than unity. In CC configuration voltage gain is less than unity. Input resistance of CE
configuration is less than CC configuration and more than CB configuration. Output resistance
of CE configuration is more than CC configuration and less than CB configuration.
Circuit setup for input characteristics:
Experiment procedure:
.Connect circuit as shown in the circuit diagram for input characteristics
.Connect variable power supply 0-30V at base circuit and collector circuit.
.Keep Vcc fix at 0V (Or do not connect Vcc)
.Increase VBB from 0V to 20V, note down readings of base current Ib and base to emitter
voltage Vbe in the observation table.
.Repeat above procedure for Vcc = +5V and Vcc = +10V
.Draw input characteristics curve. Plot Vbe on X axis and Ib on Y axis.

3. Observation table:
Sr. No. Vcc = 0V Vcc = 5V Vcc = 10V
Vbe Ib Vbe Ib Vbe Ib
1 0.52 10 0.5 10 0.5 10
2 0.54 30 0.5 30 0.56 30
3 0.54 50 0.5 50 0.56 50
4 0.54 70 0.52 70 0.56 70
5 0.55 90 0.54 90 0.56 90
6 0.55 110 0.54 110 0.57 110
7 0.56 140 0.56 140 0.57 140
8 0.56 160 0.57 160 0.57 160
9 0.57 180 0.57 180 0.57 180
10 0.57 200 0.57 200 0.57 200
Input Characteristics:
Circuit setup for output characteristics:

4. Experiment Procedure:
.Connect circuit as shown in the circuit diagram for output characteristics
.Connect variable power supply 0-30V at base circuit and collector circuit.
.Keep base current fix (Initially 0)
.Increase VCC from 0V to 30V, note down readings of collector current Ic and
collector to emitter voltage Vce in the observation table.
.Repeat above procedure for base currents Ib = 5μA, 50 μA, 100 μA. Increase base
current by increasing VBB.
.Draw output characteristics curve. Plot Vce on X axis and Ic on Y axis.
Observation table:
Sr. Ib = 0µA Ib = 5µA Ib = 50µA Ib = 100µA
No. Vce Ic Vce Ic Vce Ic Vce Ic
1 0.008 0 0.02 5 0.5 1.8 1 15.9
2 0.003 0 1.8 780 0.8 5.2 2 30.8
3 5.5 0 4.6 792 0.9 8.4 3 32.6
4 8.5 0 8.4 796 3.4 10 4 36.4
5 11.6 0 11.2 804 5 11.1 5 37.4
6 16.2 0 14.02 806 5.9 11.5 6 39.6
7 19.2 0 16.08 812 10.9 11.8 7 41.1
8 22.1 0 18 816 13 11.85 8 42.8
9 22.2 0 19.6 818 14 12.25 9 43.9
10 22.8 0 20.03 912 15 13.45 10 45.0

5. Output Characteristics:
Discussion of Results :-
In this lab we have to learnt about the behavior of transistor and also study about
thecommon emitter amplifier and also find the voltages and current with help of DMM
havingdifferent values. After that find the output and input voltages by the given circuit and
make thewaveform with the help of different values.
Conclusion:
This lab is about to common emitter characteristics of NPN transistor.After that observe the
working of common emitter amplifier. And find the input and output voltages and currents.
After that make the waveform ofdifferent values.