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IC APPLICATIONS LAB

III/IV B. TECH., I SEMESTER

STUDENT OBSERVATION MANUAL

DEPARTMENT

OF

ELECTRONICS & COMMUNICATION ENGINEERING

VEMU INSTITUTE OF TECHNOLOGY Tirupati - Chittoor Highway Road, P. Kothakota, Chittoor- 517 112.

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR

VEMU INSTITUTE OF TECHNOLOGY

DEPT. OF ELECTRONICS AND COMMUNICATION ENGINEERING

Vision of the institute

To be a premier institute for professional education producing dynamic and vibrant force of

technocrat with competent skills, innovative ideas and leadership qualities to serve the society

with ethical and benevolent approach.

Mission of the institute

Mission_1: To create a learning environment with state-of-the art infrastructure, well equipped

laboratories, research facilities and qualified senior faculty to impart high quality technical

education.

Mission_2: To facilitate the learners to foster innovative ideas, inculcate competent research and

consultancy skills through Industry-Institute Interaction.

Mission_3: To develop hard work, honesty, leadership qualities and sense of direction in rural

youth by providing value based education.

Vision of the Department

To become a centre of excellence in the field of Electronics and Communication Engineering

and produce graduates with Technical Skills, Research & Consultancy Competencies, Life-long

Learning and Professional Ethics to meet the challenges of the Industry and Society.

Mission of the Department

Mission_1: To enrich Technical Skills of students through Effective Teaching and Learning

practices for exchange of ideas and dissemination of knowledge.

Mission_2: To enable the students with research and consultancy skill sets through state-of-the

art laboratories, industry interaction and training on core & multidisciplinary technologies.

Mission_3: To develop and instill creative thinking, Life-long learning, leadership qualities,

Professional Ethics and social responsibilities among students by providing value based

education.

Programme Educational Objectives ( PEOs)

PEO_1: To prepare the graduates to be able to plan, analyze and provide innovative ideas to

investigate complex engineering problems of industry in the field of Electronics and

Communication Engineering using contemporary design and simulation tools.

PEO_2: To provide students with solid fundamentals in core and multidisciplinary domain for

successful implementation of engineering products and also to pursue higher studies.

PEO_3: To inculcate learners with professional and ethical attitude, effective communication

skills, teamwork skills, and an ability to relate engineering issues to broader social context at

work place.

Programme Outcome (POs)

PO_1: Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals, and an engineering specialization to the solution of complex engineering

problems.

PO_2: Problem analysis: Identify, formulate, review research literature, and analyze complex

engineering problems reaching substantiated conclusions using first principles of mathematics,

natural sciences, and engineering sciences.

PO_3: Design/development of solutions: Design solutions for complex engineering problems

and design system components or processes that meet the specified needs with appropriate

consideration for the public health and safety, and the cultural, societal, and environmental

considerations.

PO_4: Conduct investigations of complex problems: Use research-based knowledge and

research methods including design of experiments, analysis and interpretation of data, and

synthesis of the information to provide valid conclusions.

PO_5: Modern tool usage: Create, select, and apply appropriate techniques, resources, and

modern engineering and IT tools including prediction and modeling to complex engineering

activities with an understanding of the limitations.

PO_6: The engineer and society: Apply reasoning informed by the contextual knowledge to

assess societal, health, safety, legal and cultural issues and the consequent responsibilities

relevant to the professional engineering practice.

PO_7: Environment and sustainability: Understand the impact of the professional engineering

solutions in societal and environmental contexts, and demonstrate the knowledge of, and need

for sustainable development.

PO_8: Ethics: Apply ethical principles and commit to professional ethics and responsibilities

and norms of the engineering practice.

PO_9: Individual and team work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.

PO_10: Communication: Communicate effectively on complex engineering activities with the

engineering community and with society at large, such as, being able to comprehend and write

effective reports and design documentation, make effective presentations, and give and receive

clear instructions.

PO_11: Project management and finance: Demonstrate knowledge and understanding of the

engineering and management principles and apply these to one’s own work, as a member and

leader in a team, to manage projects and in multidisciplinary environments.

PO_12: Life-long learning: Recognize the need for, and have the preparation and ability to

engage in independent and life-long learning in the broadest context of technological change.

Programme Specific Outcome (PSOs)

PSO_1: Higher Education: Qualify in competitive examinations for pursuing higher education

by applying the fundamental concepts of Electronics and Communication Engineering domains

such as Analog & Digital Electronics, Signal Processing, Communication & Networking,

Embedded Systems, VLSI Design and Control Systems etc..

PSO_2: Employment: Get employed in allied industries through their proficiency in program

specific domain knowledge, specialized software packages and Computer programming or

become an entrepreneur.

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY ANANTAPUR

III B.Tech. I-Sem (ECE)

(15A04507) IC APPLICATIONS LAB

Course Outcomes(COs):

C317.1: Analyze the characteristics of OP Amp with negative feedback

C317.2: Construct regenerative feedback circuit, integrator, differentiator and active analog filters using

Operational Amplifier

C317.3: Design VCO, AGC, PLL, AVC using linear ICs

C317.4: Design a function generator using op- Operational Amplifier.

Experiments to be conducted:

1. Study the characteristics of negative feedback amplifier.

2. Design of an Instrumentation amplifier

3. Study the characteristics of regenerative feedback system with extension to design an astable

multivibrator.

4. Study the Characteristics of Integrator Circuit.

5. Design of Analog filters-I

6. Design of Analog filters-II

7. Design of self-tuned Filter.

8. Design of a function generator.

9. Design of a Voltage Controlled Oscillator.

10. Design of a Phase Locked Loop (PLL).

11. Automatic Gain Control (AGC) Automatic Volume Control (AVC)

12. Design of a Low Drop out Regulator.

13. DC-DC Converter.

CONTENTS

S. No Name of Experiment Page No

1 Negative Feedback Amplifier 1-4

2 Instrumentation Amplifier 5-6

3 Astable Multivibrator Characteristics 7-8

4 Integrator Circuit Characteristics 9-10

5 Design of Analog filters-I 11-13

6 Design of Analog filters-II 14-15

7 Design of self-tuned Filter 16-17

8 Design of Function Generator 18-20

9 Design of Voltage Controlled Oscillator 21-22

10 Design of Phase Locked Loop 23-24

11 Automatic Gain Control (or) Automatic Volume Control 25-26

12 Low Drop Out Regulator 27-28

13 DC-DC Convertor 29-30

ADDITIONAL EXPERIMENTS

14 Design of a Second Order Active Low Pass Filter 31-34

15 Design of a Second Order Active High Pass Filter 35-37

DOS & DONTS IN LABORATORY

1. While entering the Laboratory, the students should follow the dress code

(Wear shoes, White Apron & Female students should tie their hair back).

2. The students should bring their observation note book, practical manual,

record note book, calculator, necessary stationary items and graph sheets if

any for the lab classes without which the students will not be allowed for

doing the practical.

3. All the equipments and components should be handled with utmost care.

Any breakage/damage will be charged.

4. If any damage/breakage is noticed, it should be reported to the instructor

immediately.

5. If a student notices any short circuits, improper wiring and unusual smells

immediately the same thing is to be brought to the notice of technician/lab in

charge.

6. At the end of practical class the apparatus should be returned to the lab

technician and take back the indent slip.

7. Each experiment after completion should be written in the observation note

book and should be corrected by the lab in charge on the same day of the

practical class.

8. Each experiment should be written in the record note book only after getting

signature from the lab in charge in the observation note book.

9. Record should be submitted in the successive lab session after completion of

the experiment.

10. 100% attendance should be maintained for the practical classes.

SCHEME OF EVALUVATION

S NO NAME OF

EXPERIMENT DATE

MARKS AWARDED

TOTAL

(30M) Record

(10M)

Observati

on (10M)

Viva

voce

(10M)

Attendan

ce (10M)

1 Negative feedback

amplifier

2 Instrumentation amplifier

3 A stable multivibrator

characteristics

4 Integrator circuit

characteristics

5 II order butter worth band

pass filter Characteristics

6 Notch filter characteristics

7 Self tuned filter

characteristics

8 Function generator

9 Voltage controlled

oscillator

10 Phase locked loop

11 Automatic gain control

12 Low drop out regulator

13 Dc-dc convertor

Signature of Lab In-charge

IC APPLICATIONS LAB III B.Tech I SEM

VEMU INSTITUTE OF TECHNOLOGY, DEPT OF E.C.E Page 1

Exp. No: 1 Date:

STUDY THE CHARACTERISTICS OF NEGATIVE FEEDBACK

AMPLIFIER

AIM: To study and design the following amplifiers using TL082 OP-AMP

a) A Unity gain amplifier

b) An inverting amplifier

c) A non-inverting amplifier

APPARATUS REQUIRED:

S. No. Equipment/Component name Specifications/Value Quantity

1 IC TL082 1

2 Resistors 1kΩ

10kΩ

2

1

3 Regulated Power supply (0 – 30)V 1

4 Function Generator (0 – 3MHz), 20V p-p 1

5 Cathode Ray Oscilloscope 20MHz 1

6 Digital Multimeter 3 ½ digit display 1

7 Connecting wires -

8 Bread board trainer 1

CIRCUIT DIAGRAMS:

Unity –Gain Amplifier

Figure: 1



Inverting Amplifier

Figure: 2

Non-Inverting Amplifier

Figure: 3

PROCEDURE:

Unity – Gain Amplifier

1. Connect the circuit as shown in figure: 1.

2. Apply a Sine wave of 5VP-P at 1 KHz frequency at the non-inverting terminal.

3. Study the effect of slew rate.

4. Observe the output waveform

5. Plot the waveform on a graph.

Inverting Amplifier




2. Apply a Sine wave of 5VP-P at 1 KHz frequency at the inverting terminal.




Non-Inverting Amplifier


2. Apply a Sine wave of 5VP-P at 1 KHz frequency at the non-inverting terminal.




TABULAR COLUMN:

Unit- Gain Amplifier:

S. No Waveform Amplitude Time period

Inverting Amplifier:


Non-Inverting Amplifier:




MODEL WAVEFORMS:

RESULT:



Exp. No: 2 Date:

DESIGN OF AN INSTRUMENTATION AMPLIFIER

AIM:

To design Instrumentation Amplifier of a differential mode gain ‘A’ using three amplifiers.

APPARATUS:


1 Analog Signal Lab Kit Pro 1


3 Function Generator (0 – 3MHz), 20V p-p



CIRCUIT DIAGRAM:

J1

J2

J2

J1

J2

J1

j2

J1

-

++

3

2

1

84

U1 TL082

-

++

3

2

1

84

U2 TL082

-

++

3

2

1

84

U3 TL082

R1 2k

R2 2k

R3 1

kR

5 1

0k

R6 1k

R7 1k

R4 1

k

V3 10

V4 10

VF1

+

VG1

+

VG2

Figure: 1

PROCEDURE:

1. Connect the circuit as shown in figure:1

2. Apply the power supplies as VCC = +10V and VEE = -10V.

Apply the Inputs of sine wave with 1KHz frequency and amplitudes of 10Vp-p , 2Vp-p at



1. VG1 and VG2 respectively.

2. Observe the output waveform at terminal VF1.

3. Plot the input and output waveforms.

CALCULATIONS:

Theoretical Gain:

Practical Gain:

Gain = Vout / (V2-V1)

MODEL WAVEFORMS:

RESULT:



Exp. No: 3 Date:

STUDY THE CHARACTERISTICS OF REGENERATIVE

FEEDBACK SYSTEM WITH EXTENSION TO DESIGN AN

ASTABLE MULTIVIBRATOR

AIM: To design and study the characteristics of Astable multivibrator (Regenerative circuit)

using 741 OP-AMP

APPARATUS:


1 IC 741 1

2 Resistors 10kΩ 3

3 Capacitor 0.01µF 1





CIRCUIT DIAGRAM:

Figure: 1

PROCEDURE:





3. Observe the output at terminal Vo .

4. Measure the frequency of the oscillations.

5. Compare the Theoretical and Practical frequency values.

6. Plot the output waveform.

CALCULATIONS:

Where ‘T’ is the time period

T =

+

-1

1ln2RC where R=Rf

where β = 21

2

RR

R

+

TABULAR COLUMN:

S. No.

Theoretical Practical

Time period

T (ms)

Frequency

F (KHz)

Time period

T (ms)

Frequency

F (KHz)

output voltage

V0 (V)

MODEL WAVEFORMS:

RESULT:



Exp. No: 4 Date:

STUDY THE CHARACTERISTICS OF INTEGRATOR CIRCUIT

AIM: To design and study the characteristics of integrator circuit using 741 OP-AMP

APPARATUS REQUIRED:


1 IC 741 1

2 Resistors 2.2kΩ

10kΩ

2

1

3 Capacitor 0.01µF 1






CIRCUIT DIAGRAM:

Figure: 1

PROCEDURE:



3. Apply square wave input at 1KHz and 2Vp-p amplitude, choose the time period of the

signal T RF CF

4. Observe integrator output at terminal Vo.

5. Plot the input and output waveforms.



PRECAUTIONS:

1. Connections should be made properly.

2. Avoid loose connections.

MODEL WAVEFORMS:

RESULT:



Exp. No: 5 Date:

DESIGN OF ANALOG FILTERS-I

AIM: To design and study the frequency response of active Low Pass Filter and High Pass Filters

by using op-amps.

APPARATUS REQUIRED:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

J1

j2

j2

J1

j2

J1

j2

J1

j2

J1

-

++

3

2

1

84

U1 TL082

-

++

3

2

1

84

U2 TL082

-

++

3

2

1

84

U3 TL082

-

++

3

2

1

84

U4 TL082

C1 1u C2 1uR1 10k

R2 1kR3 3k R4 1k

R5 1k

R8 1k R9 1k

R10 10k

+ VG1

V1 10

V2 10

BPF

LPF

BSF

HPF

PROCEDURE:

1. Connect the circuit as shown in the fig.

2. Apply the power supplies as VDD = +10V and VSS = -10V.

3. Apply a Sine wave of 2VP-P at 1 KHz frequency at VG1 inverting input terminal.

4. Vary the frequency of input signal from 100Hz to 50kHz and note down the output

voltages of LPF, HPF, BPF and BSF.

5. Plot the output voltage vs frequency of LPF, HPF, BPF and BSF on semi log graphs.



MODEL WAVEFORMS:

Frequency response of LPF Frequency response of HPF

Frequency response of BPF Frequency response of BSF

TABULAR COLUMNS:

Input voltage Vin =

a) LPF b) HPF

Sl.

No.

Freq.

(Hz)

i/p voltage

Vi(V)

o/p voltage

Vo (V)

Gain

(dB)

Sl.

No.

Freq.

(Hz)

i/p voltage

Vi(V)

o/p voltage

Vo (V)

Gain

(dB)



c) BPF d) BSF

CALCULATIONS:

RESULT:

Sl.

No.

Freq.

(Hz)

i/p voltage

Vi(V)

o/p voltage

Vo (V)

Gain

(dB)

Sl.

No.

Freq.

(Hz)

i/p voltage

Vi(V)

o/p voltage

Vo (V)

Gain

(dB)



Exp. No: 6 Date:

DESIGN OF ANALOG FILTERS-II

AIM:

To design and study the frequency response of Notch filter by using op-amps..

APPARATUS REQUIRED:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

PROCEDURE:



3. Apply a Sine wave of 2VP-P at 1 KHz frequency at VG1 inverting input terminal.

4. Vary the frequency of input signal from 100Hz to 50kHz and note down the output

voltages of notch filter.

5. Plot the output voltage vs frequency of notch filter on semi log graphs.



MODEL WAVEFORMS:

TABULAR COLUMNS:

Input voltage Vin =

Notch filter:

RESULT:

Sl.

No.

Freq.

(Hz)

i/p voltage

Vi(V)

o/p voltage

Vo (V)

Gain

(dB)



Exp. No: 7 Date:

DESIGN OF A SELF-TUNED FILTER

AIM:

Design and test a high-Q band pass self-tuned filter for a given center frequency.

APPARATUS REQUIRED:


1. Op-amp IC TL082 1

2 Universal active filters UAFA2 1

3 Resistors 1KΏ 10

4 Capacitors 1µf 1





9 IC bread board - 1

10 CRO probes - As per required

CIRCUIT DIAGRAM:

PROCEDURE:


2. Apply a Square wave of fixed amplitude as a input signal



3. Obtain the output for 1KHz input frequency.

4. Measure the output amplitude at varying input frequency at fixed input amplitude.

5. Output amplitude should remain constant for varying input frequency with the lock

range of system.

6. Plot the input and output waveforms on graph.

MODEL WAVEFORMS:

TABULAR COLUMN:

RESULT:



Exp. No: 8 Date:

DESIGN OF FUNCTION GENERATOR

AIM:

To generate square wave and triangular wave form by using 741 OPAMPs.

APPARATUS REQUIRED:


1 IC 741 2

2 Resistors 10kΩ

2.2kΩ

4

2

3 Capacitor 0.01µF

0.1µF

1

1





CIRCUIT DIAGRAM:

Square wave generator:

Figure 1



Triangular wave generator:

Figure 2

PROCEDURE:

Square wave generator:



3. Observe the square waveform at the output terminal VO1.




Triangular wave generator:


2. Apply the power supplies VCC = +12V and VEE = -12V.

3. Observe the square waveform at the output terminal VO2.




CALCULATIONS:

Where T is the time period

T =

+

-1

1ln2RC where R=Rf



Where, β = 21

2

RR

R

+

MODEL WAVE FORMS:

TABULAR COLUMN:

S.

No.

Theoretical Practical

Square wave Triangular wave

Time

period

T (ms)

Frequency

F (KHz)

Time

period

T (ms)

Frequency

F (KHz)

output

voltage

V0 (V)

Time

period

T (ms)

Frequency

F (KHz)

output

voltage

V0 (V)

RESULT:



Exp. No: 9 Date:

DESIGN OF A VOLTAGE CONTROLLED OSCILLATOR

AIM:

To design a Voltage Controlled Oscillator (VCO) circuit by using op-amps.

APPARATUS REQUIRED:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

PROCEDURE:



3. By varying control voltage, VC , note down the variations in frequency.

4. Observe the output waveforms at terminals Vo1 and Vo2.

5. Plot the output waveforms.



MODEL WAVEFORMS:

RESULT:



Exp. No: 10 Date:

DESIGN OF A PHASE LOCKED LOOP

AIM:

Design and test PLL to get locked to a given frequency f. Measure the locking range of the

system and also measure the change in phase of the output signal as input frequency is varied with

in the lock range.

APPARATUS REQUIRED:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

PROCEDURE:


2. Apply the power supplies as VCC = +10V.

3. By varying input voltage, note down the variations in frequency.

4. Observe the output waveforms.

5. Plot the output waveforms.



MODEL WAVEFORMS:

TABULAR COLUMN:

RESULT:



Exp. No: 11 Date:

AUTOMATIC GAIN CONTROL (AGC)/AUTOMATIC VOLUME

CONTROL (AVC)

AIM: To design and study the characteristics of AGC/AVC circuit by using Op-Amp.

APPARATUS:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

MODEL WAVEFORM:

input-output characteristics of AGC/AVC



PROCEDURE:



3. Apply a Sine wave of 2VP-P at 1 KHz frequency to the multiplier 1.

4. Observe the output at terminal Vo and note down the values of input and output voltages.

5. Calculate Vpi by using formula

6. Plot the transfer characteristics on graph.

TABULAR COLUMN:

Sl. No. input voltage

Vi (V)

output voltage

V0 (V)

RESULT:



Exp. No:12 Date:

LOW DROP OUT REGULATOR

AIM: Design and test a Low Dropout regulator using op-amps for a given voltage regulation

characteristic and compare the characteristics with TPS7250 IC.

APPARATUS:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

PROCEDURE:



3. Apply reference voltage as Vref = 5V to the inverting input terminal of op-amp.

4. Observe the dc output at terminal Vo .

5. Calculate Vo by using formula



6. Plot the waveforms on graph

MODEL WAVEFORMS:

CALCULATIONS:

RESULT:



Exp. No: 13 Date:

DC-DC CONVERTER

AIM: To design and study the characteristics of AGC/AVC circuit by using Op-Amp.

APPARATUS:


1 ASLK PRO Kit - 1





CIRCUIT DIAGRAM:

MODEL WAVEFORMS:



PROCEDURE:


2. Apply the power supplies as VDD = +10V.

3. Apply a triangular wave of 6VP-P at 1 KHz frequency to the non-inverting input terminal of

op-amp.

4. Apply reference voltage as Vref = 5V to the inverting input terminal of op-amp.

5. Observe the dc output at terminal Vo .

6. Calculate Vo by using formula

7. Plot the waveforms on graph.

CALCULATIONS:

Theoretical output voltage, Vo

Practical output voltage, V0 =

RESULT:



Exp. No: Date:

1. DESIGN OF A SECOND ORDER ACTIVE LOW PASS FILTER

AIM: To plot the frequency response of Butterworth LPF (Second order) and find the high cut-

off frequency.

APPARATUS: Bread Board Function Generator CRO Probes Connecting Wires 741 Op-amp,

Resistors, Capacitors

THEORY: Filters are classified as follows: Based on components used in the circuit

• Active filters – Use active elements like transistor or op-amp(provides gain) in addition to

passive elements

• Passive filters – Use only passive elements like resistors, capacitors and inductors, hence

no gain here. Based on frequency range

➢ Low pass filter(LPF) – Allows low frequencies

➢ High pass filter(HPF) – Allows high frequencies

➢ Band pass filter(BPF) – Allows band of frequencies

➢ Band reject filter(BRF) – Rejects band of frequencies

All pass filter – Allows all frequencies but with a phase shift Active Filter is often a frequency –

selective circuit that passes a specified band of frequencies and blocks or attenuates signals of

frequencies outside this band. These Active Filters are most extensively used in the field of

communications and signal processing. They are employed in one form or another in almost all

sophisticated electronic systems such as Radio, Television, Telephone, Radar, Space Satellites,

and Bio-Medical Equipment. Active Filters employ transistors or Op – Amps in addition to that of

resistors and capacitors. Active filters have the following advantages over passive filters. (1)

Flexible gain and frequency adjustment. (2) No loading problem (because of high input

impedance and low output impedance) and (3) Active filters are more economical than passive

filters. A Second – Order Low – Pass Butterworth filter uses RC networks for filtering. Note that

the op-amp is used in the non-inverting configuration; hence it does not load down the RC

network. Resistors R1 and RF determine the gain of the filter.

The gain magnitude equation of the Low – Pass filter can be obtained by converting equation into

its equivalent polar form, as follows.



The operation of the low – pass filter can be verified from the gain magnitude equation.

Thus the Low – Pass filter has a constant gain AF from 0 Hz to the almost high cut-off frequency,

fH, it has the gain 0.707AF at exactly fH, and after fH it decreases at a constant rate with an

increase in frequency. The gain decreases 40 dB (= 20 log 102) each time the frequency is

increased by 10. Hence the rate at which the gain rolls off after fH is 40 dB/decade. The

frequency f = fH is called the cut-off frequency because the gain of the filter at this frequency is

down by 3 dB (=20log 0.707) from 0 Hz. Other equivalent terms for cut-off frequency are -3dB

frequency, break frequency, or corner frequency. DESIGN:

1. Choose a value for the high cut-off frequency, fH(1 KHz)

2. To simplify the design calculations, set R2=R3=R and C2=C3=C. Then choose a value of

C≤1μF(0.0047 μF)

3. Calculate the value of R using the equation

4. Finally, because of the equal resistor (R2=R3) and capacitor (C2=C3) values, the pass band

voltage gain of the second-order low-pass filter has to be equal to 1.586. That

is, Rf = 0.586R1. This gain is necessary to generate Butterworth response. Hence choose a value

of R1≤100KΩ (33 KΩ) and calculate the value of Rf.



CIRCUIT DIAGRAM

PROCEDURE:

1. Connect the components/equipment as shown in the circuit diagram.

2. Switch ON the power supply.

3. Connect channel -1 of CRO to input terminals (Vin) and channel -2 to output terminals (Vo).

4. Set Vin = 1V & fin=10Hz using function generator.

5. By varying the input frequency in regular intervals, note down the output voltage.

6. Calculate the gain (Vo/Vin) and Gain in dB = 20 log (Vo/Vin) at every frequency.

7. Plot the frequency response curve (taking frequency on X-axis & Gain in dB on Y-axis) using

Semi log Graph.

8. Find out the high cut-off frequency, fH (at Gain= Constant Gain, Af – 3 dB) from the

frequency response plotted.

9. Verify the practical (fH from graph) and the calculated theoretical cut-off frequency (fH =

1/2πRC ).



THEORETICAL Cut-off frequency:

fH = 1 / (2πRC) = high cut-off frequency of the Low pass filter.

=

PRACTICAL Cut-off frequency (from Graph) :

fH = high cut-off frequency of the Low pass filter = 3dB cut-off frequency

=

RESULT:



2. DESIGN OF A SECOND ORDER ACTIVE HIGH PASS FILTER

AIM: To plot the frequency response of Butterworth HPF (Second order) and find the low cut-off

frequency.

APPARATUS: Bread Board Function Generator CRO Probes Connecting Wires 741 Op-amp,

Resistors, Capacitors

THEORY: Second Order High Pass Filter consists of RC networks for filtering. Second Order

High Pass filter can be constructed from a Second Order Low Pass filter simply by interchanging

frequency determining components R & C . Op-Amp is used in the non – inverting configuration.

Resistor R1 and RF determine the gain of the Filter. The voltage gain magnitude equation of the

second order High-pass filter is

where f = Operating (input) frequency.

This is the frequency at which the magnitude of the gain is 0.707 times its pass band value.

Obviously, all frequencies higher than fL are Pass Band frequencies, with the highest frequency

determined by the closed-loop bandwidth of the OP-Amp. The operation of the high–pass filter

can be verified from the gain magnitude equation.



For example, in the first order High – Pass filter the gain rolls – off or increases at the rate of

20dB/decade in stop band, that is for input signal frequency lesser than Low cut-off frequency (fL

) ; For Second – Order High Pass filter the roll–off rate is 40dB / decade. High Pass filter has

constant gain AF, after the Low cut-off frequency onwards (fL).

DESIGN: Follow the same procedure as given for low-pass filter.

CIRCUIT DIAGRAM:

PROCEDURE:

1. Connect the components/equipment as shown in the circuit diagram.

2. Switch ON the power supply.

3. Connect channel -1 of CRO to input terminals (Vin) and channel -2 to output terminals (Vo).

4. Set Vin = 1V & fin=10Hz using function generator.

5. By varying the input frequency in regular intervals, note down the output voltage.

6. Calculate the gain (Vo/Vin) and Gain in dB = 20 log(Vo/Vin) at every frequency.

7. Plot the frequency response curve (taking frequency on X-axis & Gain in dB on Y-axis) using

Semi log Graph.

8. Find out the low cut-off frequency, fL (at Gain= Constant Gain, Af – 3 dB) from the frequency

response plotted.

9. Verify the practical (fL from graph) and the calculated theoretical cut-off frequency (fL =

1/2πRC).



EXPECTED WAVEFORM:

RESULT:

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