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COLLEGE OF ENGINEERING
AND ARCHITECTURE

ELECTRONICS
ENGINEERING DEPARTMENT

 

 

2ND SEMESTER
AY 2017-2018

PRELIM

 

ELECTRONIC CIRCUITS ANALYSIS AND
DESIGN

ECE 402

EE41FC1

 

Frequency
Response of Common-Base and
Common-Emitter Amplifiers

LABORATORY NO. 2

 

 

 

Submitted
to:

Engr. Reginald Phelps T. Laguna

 

Submitted
on:

January 9, 2017

Submitted
by:

Braga, Nolidhon A.
Cave, Levi John O.
Deocareza, Vicente II A.
Espinas, Jessa Eunice L.
Gumaru, Jhenord
Tampoco, Eugenics P.

 

Frequency Response of
Common-Base and Common-Emmiter Amplifiers

Laboratory
No. 2

Abstract—The word amplifier is used in this laboratory report is
a circuit (or stage) in manner, by utilizing a single active device rather than
a complete a system such as an integrated circuit operational amplifier. The
amplifier is a device that is used to enhance the power of a signal. This is done
by taking energy from a PSU (power supply unit) and controlling the output to
duplicate the shape of the input signal but with a larger (voltage or current)
amplitude. In this sense, it may be thought of as modulating the voltage or
current of the power supply to produce its output.

                                                                                                                                                    
I.      
Introduction      

In Electronics, Small signals amplifiers
are commonly used devices as they can amplify a relatively small input signal,
for example from a sensor such as a photo-device, into a much larger output
signal to drive a relay, lamp or loudspeaker.

      In this experiment we
would tackle different concepts regarding the frequency response of a
common-base and common-emitter amplifier configurations.

                                                                                                                                                            
II.      
Objectives

In this laboratory experiment our group
has the following objectives: (1) to characterize how frequency affects the
gain of an amplifier;(2) to determine how the capacitance affects the gain of
an amplifier;(3) to determine the upper and lower cut-off frequency of an
amplifier. (4) to be able to utilize and apply different concepts regarding
this topic and (5) to be able to create and be successful in gathering data in
this experiment.

                                                                                                                                                    
III.      
Calculations

 

A.      Calculation
for Common Base

RTH
= 9375 k?

VTH = VB

VB = VCC*R2/R1+R2

VB = 0.9375 V

 

VE = VB ­— VBE

VE
= 0.9375 — 0.7

VE = 0.2375 V

V­­­R1 = 13.39 V

VR2 = 0.871 V

 

IB
= 13.39 V/150 k ? — 0.871V/10 k ?

IB = 2.1667×10-6 A

 

IE = VE/RS

IE = 0.2375V/1000 ?

IE = 0.2375 mA

 

IC = IE — IB

IC
= 0.2375 mA — 2.1667×10-6A

IC = 0.2353 mA

 

? = hfe
= IC/IB

Hfe =
0.2353 mA/2.1667 ?A

Hfe = 108.615

 

1/t1 = 1/t11 + 1/t1

T11
= C1{R3+R2||(hfc/1+hfc)}

T11 = 2.10 mS

 

T1­
= C2{R1||R2||(hie+hfc)(R3*RS/R3+RS)}

T1 = 271 mS

 

1/t1 = 1/2.10mS + 1/271mS

1/t1 = 479.88 S

 

1/t2 = 1/C3(R4+R6)

1/t2 = 3.33 S

 

fL
= 1/2? ?(439.880)2 + (3.33)2

fL = 76.37 Hz

 

Vout =
0.707(2.95)

Vout = 2.0927 V

 

 

 

A.       Common
Emitter Calculation

 

R1S
= RTH

RTH =
R1||R2

RTH = 9375?

RC
= RE||(RS+hIe/hfe)

RC
= 1k?||(9375+5100/1000)

RC = 117.6?

 

FLe
= 1/2? (117.6)(47µF)

FLE = 28.79 Hz

 

Vout =
3.6(0.704)

Vout =
2.5452 V

 

                                                                                                                                                       
IV.      
Simulations

LTSpice is freeware software that is used
to implement a Simulation Program with Integrated Circuit Emphasis (SPICE)
simulator of electronic circuit. The software is utilized in this project to
create a precise measurement and outcome.

 

A.                  
Common
Emitter Simulation

Fig. 1.0 –Current of Input Signal and
Output Signal

Fig. 1.1 – Input Signal at the Base

Fig. 1.2 – Current of Input and Output
Signal

 

B.                  
Common
Base Simulation

Fig. 1.3 – Voltage Comparison at the Input
and Output Signal

 

Materials,
Tools, Equipment and Testing Devices

·        
Oscilloscope

·        
Power
supply

·        
Function
Generator

·        
Resistors
(150K ohms, 10K ohms, 15K ohms, 1K ohms, 100 ohms)

·        
Capacitor
(47 uF, 10 uF)

·        
Transistor

·        
Breadboard

·        
Alligator
Wires / Cable Wires

·        
Digital
Multimeter

 

A.       Common Emitter

Output graph of  Common Emitter

 

B.       Common Base

 

                                                                                                             
V.      
Navegating
equipment to gather accurate data

 

 

                .Data and Results 

A.       Common Base Amplifier

 

FL

FH

Calculated

Measured

Measured

76.37 Hz

50Hz

1000Hz

This table shows the calculated and measured
lower frequency (FL) and higher frequency (FH)

10x Frequency

5

15

20

35

45

Vin

1.03mV

1.00mV

1.05 mV

.98 mV

1.08 mV

Vout

302 mV

420.1 mV

653.1 mV

830 mV

1.02V

Gain

293.2

420.1

62.2

846.94

944.44

Gaindb

49.43

52.47

55.88

58.56

59.5

 

10x
Frequency

60

70

80

90

100

Vin

1.20 mV

1.23 mV

1.02 mV

1.03 mV

1.03 mV

Vout

1.350V

1.56V

1.69V

1.81V

1.99V

Gain

1125

1268.29

1656.86

1757.28

1895.24

Gaindb

59.5

61.02

66.39

64.9

65.55

 

The relationship between gain and frequency is directly
proportional

 

B.       Common Emitter Amplifier

 

FL

FH

Measured

Calculated

Measured

50 Hz

28.79 Hz

1000 Hz

 

 

 

10x
Frequency

5

15

25

40

50

Vin

0.99mV

1 mV

1.02 mV

1.35V

1.56V

Vout

400 mV

850 mV

1.1V

1.35 V

1.56 V

Gain

404.04

850

1078.43

1285.71

1471.07

Gain db

53.13

58.59

60.66

62.18

63.36

 

10x
Frequency

60

70

80

10

100

Vin

1.73V

1.85V

2.01V

2.74V

2.53V

Vout

1.73 V

1.85 V

2.01 V

2.74 V

2.53 V

Gain

1572.73

1608.7

1717.95

1866.67

1946.15

Gain db

63.93

64.13

64.7

65.42

65.78

 

The relationship between gain and frequency is directly
proportional

 

                                                                                                        
VI.      
Problems
Encountered and  Actions Taken

Problems Encountered and Actions Taken

Activity No.

Problems
Encountered

Actions
Taken

1

·         
Disrupted Waveform
·         
wrong connection of wiring and components

·         
re-configuring the oscilloscope
·         
analyzing and thoroughly reconnecting

 

                                                                                                                 
VII.      
Conclusions
and Recommendations

A.       Conclusions

We therefore we conclude that the
emitter current is greater than any other current in the transistor, being the
sum of base and collector currents. With common-emitter amplifier and
common-base amplifier configurations, the transistor parameter most closely
associated with gain was ?. In the common-base circuit, we follow another basic
transistor parameter the ratio between base current and emitter current which
is a fraction always less than 1.

Recommendations

Soon, our group hoped to further explore
deeper concepts and theories regarding this topic. They hoped to utilize the
knowledge and skills they acquired in the succeeding project.

The following are the list of
recommendation needed to complete the project:

(1)   
By
following the instruction carefully.

(2)   
Understanding
and applying the concepts behind the experiment.

(3)   
A
follow-up simulation regarding this experiment.

      These are the key
takeaways that will ensure that the project will be successful; together with
teamwork, cooperation, and proper mindset.

                                                                                                                                                       
VIII.      
Summary

  Small
signals amplifiers are commonly used devices as they can amplify a relatively
small input signal. The common-base configuration shows the signal source and
the load share the base of the transistor as a common connection point while
the common-emitter configuration shows both the signal source and the load
share the emitter lead as a common connection point. The common-emitter
configuration commonly called as the “Voltage Divider Biasing” is a type of
biasing arrangement that uses two resistors as a potential divider network
across the supply with their center point supplying the required Base bias
voltage to the transistor.

 

                                                                                                                                      
IX.      
Questions
and Answers

1.    
How does frequency relate to the gain of
an amplifier?

 

2.    
What is the importance of knowing the
frequency response of an amplifier?

 

 

3.    
What is the basis in getting the cut-off
frequency at 0.707 times the maximum output value?

 

4.    
Why is it necessary to maintain the input
signal at a constant level?

 

 

Task
Distribution

Name of the Participant

Task Distribution

Cave, Levi John O.

Documentation

Braga, Nolidhon A.

Documentation

Deocareza, Vicente II A.

Documentation, and Computation

Espinas, Jessa Eunice L.

Documentation, and Computation

Gumaru, Jhenord

Documentation

Tampoco, Eugenics P.

Computation

 

References

Horowitz P., and Winfield H., (1989). The Art of
Electronics (2nd ed.). Cambridge University Press. pp. 102–104. ISBN 978-0-521-37095-0.

Y. Yorozu, M. Hirano, K. Oka, and Y. Tagawa, “Electron
spectroscopy studies on magneto-optical media and plastic substrate interface,”
IEEE Transl. J. Magn. Japan, vol. 2, pp. 740-741, August 1987 Digests 9th
Annual Conf. Magnetics Japan, p. 301, 1982

M. Young, The Technical Writer’s Handbook. Mill Valley,
CA: University Science, 1989.

 

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