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LIC & LIC & LIC & LIC & Communication Lab ManualCommunication Lab ManualCommunication Lab ManualCommunication Lab Manual SSIT, TumkurSSIT, TumkurSSIT, TumkurSSIT, Tumkur

LIC & LIC & LIC & LIC & COMMUNICATION LAB MANUALCOMMUNICATION LAB MANUALCOMMUNICATION LAB MANUALCOMMUNICATION LAB MANUAL FORFORFORFOR

V SEMESTER B.E (V SEMESTER B.E (V SEMESTER B.E (V SEMESTER B.E (E&E&E&E&C)C)C)C)

(For private circulation only)

NAME: ___________________________NAME: ___________________________NAME: ___________________________NAME: ___________________________

DEPARTMENT OF DEPARTMENT OF DEPARTMENT OF DEPARTMENT OF ELECTRONICS & COMMUNICATIONELECTRONICS & COMMUNICATIONELECTRONICS & COMMUNICATIONELECTRONICS & COMMUNICATION

SRI SIDDHARTHA INSTITUTE OF TECHNOLOGYSRI SIDDHARTHA INSTITUTE OF TECHNOLOGYSRI SIDDHARTHA INSTITUTE OF TECHNOLOGYSRI SIDDHARTHA INSTITUTE OF TECHNOLOGY

(A Constituent College of Sri Siddhartha univer(A Constituent College of Sri Siddhartha univer(A Constituent College of Sri Siddhartha univer(A Constituent College of Sri Siddhartha university)sity)sity)sity)

MARLUR, TUMKURMARLUR, TUMKURMARLUR, TUMKURMARLUR, TUMKUR----572105572105572105572105


CONTENTSCONTENTSCONTENTSCONTENTS

LIC:LIC:LIC:LIC:

1.1.1.1. Schmitt Trigger Design and test a Schmitt trigger circuit for the Schmitt Trigger Design and test a Schmitt trigger circuit for the Schmitt Trigger Design and test a Schmitt trigger circuit for the Schmitt Trigger Design and test a Schmitt trigger circuit for the

given values of UTP and LTPgiven values of UTP and LTPgiven values of UTP and LTPgiven values of UTP and LTP

2.2.2.2. Design and test RDesign and test RDesign and test RDesign and test R----2R DAC using op2R DAC using op2R DAC using op2R DAC using op----ampampampamp

3.3.3.3. Design and test the following circuits using IC 555 Design and test the following circuits using IC 555 Design and test the following circuits using IC 555 Design and test the following circuits using IC 555

a.a.a.a. Astable multivibrator foAstable multivibrator foAstable multivibrator foAstable multivibrator for given frequency and duty cycler given frequency and duty cycler given frequency and duty cycler given frequency and duty cycle

b.b.b.b. Monostable multivibrator for given pulse width WMonostable multivibrator for given pulse width WMonostable multivibrator for given pulse width WMonostable multivibrator for given pulse width W

4. Precision rectifiers 4. Precision rectifiers 4. Precision rectifiers 4. Precision rectifiers –––– both Full Wave and Half Waveboth Full Wave and Half Waveboth Full Wave and Half Waveboth Full Wave and Half Wave

COMMUNICATION:COMMUNICATION:COMMUNICATION:COMMUNICATION:

5. 5. 5. 5. IIIIIIII----Order Low Pass and High Pass Active FiltersOrder Low Pass and High Pass Active FiltersOrder Low Pass and High Pass Active FiltersOrder Low Pass and High Pass Active Filters

6. 6. 6. 6. II II II II ––––Order Order Order Order Active Active Active Active BandBandBandBand Pass FilterPass FilterPass FilterPass Filter....

7. 7. 7. 7. AttenuatorsAttenuatorsAttenuatorsAttenuators

8. 8. 8. 8. ClassClassClassClass----C Tuned AmplifierC Tuned AmplifierC Tuned AmplifierC Tuned Amplifier

9. 9. 9. 9. Amplitude modulation using transistor/FET (Generation and Amplitude modulation using transistor/FET (Generation and Amplitude modulation using transistor/FET (Generation and Amplitude modulation using transistor/FET (Generation and

detection)detection)detection)detection)

10. 10. 10. 10. Pulse Amplitude ModulationPulse Amplitude ModulationPulse Amplitude ModulationPulse Amplitude Modulation

11. 11. 11. 11. Pulse Width ModulationPulse Width ModulationPulse Width ModulationPulse Width Modulation & & & & Pulse Position ModulationPulse Position ModulationPulse Position ModulationPulse Position Modulation

12. 12. 12. 12. Frequency modulation using 80Frequency modulation using 80Frequency modulation using 80Frequency modulation using 8038/220638/220638/220638/2206

13. 13. 13. 13. Pre & De Pre & De Pre & De Pre & De –––– Emphasis NetworksEmphasis NetworksEmphasis NetworksEmphasis Networks

14. 14. 14. 14. Transistor MixerTransistor MixerTransistor MixerTransistor Mixer


Testing Of Equipments before Starting the ConductionTesting Of Equipments before Starting the ConductionTesting Of Equipments before Starting the ConductionTesting Of Equipments before Starting the Conduction (Check List)(Check List)(Check List)(Check List)

1.1.1.1. OPOPOPOP AMPAMPAMPAMP

Apply sine wave of amplitude 1 volt

(1 kHz) as shown in ckt diagram, if

IC is functioning the output will be a

square wave with peaks at + VSAT

and – Vsat.

2.2.2.2. 555 Timer :555 Timer :555 Timer :555 Timer :

If IC is good for the applied 5 V D.C supply to pin no.8 then the voltage at pin

no. 5 will be 2/3 Vcc (3.3 Volts)

3.3.3.3. TransistorTransistorTransistorTransistor

Identify emitter, base and collector of the transistor, with DMM in diode

position, if transistor junctions are good it indicates a low resistance upon

forward biasing emitter base junction or collector – base junction and

indicates either OL or 1.(depending on DMM) upon reverse biasing EB or CB

junctions.

4.4.4.4. Source iSource iSource iSource impedance of ASG:mpedance of ASG:mpedance of ASG:mpedance of ASG:

1. Connect the DRB across ASG as shown in the fig keeping all the knobs at

maximum resistance position.

2. Adjust the amplitude of sine wave of 5V pp at 1 KHz.

3. Start reducing the resistance of DRB this inturn reduces the output

voltage also.

4. Continue step 3 till output signal is half of the initial value. (2.5 V pp)

5. Source resistance Rs is that value of DRB resistance when the amplitude

reduces to 2.5V

LIC & Communication lab Manual SSIT, Tumkur

1

Circuit Diagram:

Circuit diagram of Schmitt trigger for design example (1)

Y- axis

Vo volts

- X-axis

X-axis

- Vo

volts -Y axis

Transfer Characteristics (With +Ve VR)


2

Experiment No:Experiment No:Experiment No:Experiment No: 1111 DATE: __/__/____DATE: __/__/____DATE: __/__/____DATE: __/__/____

SCHMITTSCHMITTSCHMITTSCHMITT TRIGGERTRIGGERTRIGGERTRIGGER

Aim: To design and test Schmitt trigger circuit for a given value of UTP and LTP points.

Procedure:

1. Schmitt trigger is designed for the given UTP and LTP.

2. Circuit connections are made as shown in fig 1

3. Sinusoidal input signal of amplitude (larger than the UTP & LTP) is applied at the input of Schmitt

trigger.

4. Output voltage V0 is observed on CRO. The Transfer characteristic is observed and UTP and LTP

are measured and compared with designed values.

Result:

UTP (THEORITICAL) LTP (THEORITICAL) UTP (PRACTICAL) LTP (PRACTICAL)


3

Design:

VUTP = 6V, VLTP = -2V

VUTP = 6V21

2

21

1

RR

VR

RR

VRSATREF

++

+=

VLTP = -2V21

2

21

1

RR

VR

RR

VRSATREF

+−

+=

2VREFR1

VUTP + VLTP = 4 = =>

R1+R2

2VSATR2

VUTP - VLTP = 8 = = -------------------------- (2)

R1+R2

Therefore VR = 3V, assume R2 = 1kΩ => R1 = 2kΩ

T

+ββββVSAT UTP

Vi

Volts time

- ββββ VSAT LTP

+ VSAT

Vo

Volts time

- VSAT

Input- Output Waveforms (With Vr = 0)

Vm


4

Conclusion:

Result:

__________________

Staff Incharge

Assignments:

1. Define UTP, LTP & hystrisis loop.

2. Application of Schmitt trigger.


5

Circuit Diagram:

Digital i/ps from switch box

Circuit diagram of R-2R DAC

Design:

Vo= 5V,

Vref

Vout = X (D0 + 2D1 + 4D2 + 8D3)

16

Let R = 5k & 2R = 10k,

Typical Converter Relationship:-

Vout

(Full scale) Gain error

Vout Resolution or 1 LSB

Offset error

0FH Digital i/p

Typical Converter Relationship


6

Experiment No:Experiment No:Experiment No:Experiment No: 2222 DATE: DATE: DATE: DATE: __/__/______/__/______/__/______/__/____

DACDACDACDAC USINGUSINGUSINGUSING RRRR----2R2R2R2R LADDERLADDERLADDERLADDER NETWORKNETWORKNETWORKNETWORK

Aim: To Design and Test R-2R DAC using op-Amp.

Procedure: 1. Connections are made as shown in the fig 1.

2. The digital inputs are connected from switch box. The 4 – bits are increased in steps from 0000 to

1111 and at each step output voltage V0 is measured using multimeter. The readings are tabulated

and verified against the theoretical output.

3. Graph of digital inputs v/s analog output is plotted, and different parameters are as shown in fig 2 are

determined and recorded.

Tabular Column: b3 b2 b1 b0 Vout (Theoretical) Volts Vout (Practical) Volts

0 0 0 0

0 0 0 1

0 0 1 0

0 0 1 1

0 1 0 0

0 1 0 1

0 1 1 0

0 1 1 1

1 0 0 0

1 0 0 1

1 0 1 0

1 0 1 1

1 1 0 0

1 1 0 1

1 1 1 0

1 1 1 1

Conclusion:

Result:

1. LSB or Resolution =__________Volts

2. Offset error =__________Volts

3. Vout (full scale) designed =__________Volts

4. Vout (full scale) obtained =__________Volts

5. Gain error =__________Volts

__________________

Staff Incharge

Assignment:

1) Explain the working of R-2R digital to analog circuit?


7

2) Define Resolution.?

A) Circuit of Astable Multivibrator

Waveforms of Astable Multivibrator

Y

5V

Vo volts

time

2/3 Vcc

Vc (volts)

1/3 Vcc

T1 T2 time

Design 1: To Design an Astable multivibrator circuit using 555 timer for f = 1 KHz, duty cycle

= 70 % and Vout = 5 Volts.

We Know that

T1 = 0.69 RAC

T2 = 0.69 RB C and Duty Cycle = BA

BA

21

1

2R R

R R

T T

T

+

+=

+

Given duty cycle= 70 %

∴ 7.0100

70

2R R

R R

BA

BA ==+

+


8


ASTABLEASTABLEASTABLEASTABLE &&&& MONOSTABLEMONOSTABLEMONOSTABLEMONOSTABLE MULTIVIBRATORMULTIVIBRATORMULTIVIBRATORMULTIVIBRATOR

AIM: To design and test Astable and Monostable Multivibrator for the given specifications using timer IC

555.

PROCEDURE:-

I . Astable Multivibrators ( AMVs)

1. Circuit is rigged up as shown in the circuit of figure (1) and the power supply is Switched ON.

2. The output voltage waveform and the voltage across the timing capacitor are

Observed using a CRO.

3. All the relevant voltage levels like 1/3 Vcc , 2/3 Vcc are noted. T1 and T2 are also measured and

noted. The frequency of oscillation and the duty cycle are calculated and verified against the

designed values.

4. The above procedure is repeated for the circuit shown in figure (2) for any duty cycle.

5. Circuit is designed & tested for the specifications given in exercise (1).

II. Monostable Multivibrators ( MMVs)

1. Rigup the circuit as shown in the figure, switch on the power supply.

2. Apply the trigger signal using signal generator at pin no.2 (adjust the duty cycle of trigger pulses so

that its off time is less than pulse width W)

3. Observe the output signal at pin no.3

4. Capacitor voltage is observed and voltages are measured and verified.


9

or RA + RB = 0.7 RA + 1.4 RB

0.3 RA = 0.4 RB

RA = 1.33 RB

for RB = 1 k Ω , RA = 1.33 k Ω

T = T1 + T2 & T = 0.69 (RA + 2RB) C

Given f = 1 KHz, therefore T = 1msec

1ms = 0.69 [1.33 K + (2 x 1 K)] x C

Therefore C = 0.44 µF (Use two numbers of 0.22 µF in parallel)

B) Circuit of Monostable multivibrator circuit using 555 timer IC

+5 V

IN4001 4 8

R1 R

1 kΩ

C1= 0.1 µF 3 o/p

2

trigger from Pulse Gen

7

6 C 1 5

0.01 µF

Waveforms in a Monostable Multivibrator

Vtrig 5V

Trigger

0 time

V0 (V)

S S Q S

tp time

2/3Vcc

VC (V)

time


10

Design: Ton = 1ms (given)

Ton = 1.1Rc

Assume C = 0.1µF

1x10-3

1.1 R =

0.1x10-6

R = 9.09 kΩ, use standard value = 10 kΩ

Gnd 1 8 Vcc

Trigger 2 7 Discharge

Output 3 6 Threshold

Reset 4 5 Control Vg

Fig (a) : PIN DIAGRAM OF 555 timer

Note: - In the circuit diagrams that follow, only pin numbers are marked. Referring to the pin

diagram of Fig (a), specify the pin functions accordingly for all the circuit diagrams.

Conclusion:

Result:

__________________

Staff Incharge

Assignment:

1. What are multivibrators?

2. Classifications of multivibrators.

3. Mention any two applications of Astable multivibrator?

4. Define stable and quasi stable states.


11

a) Half Wave Precision Rectifier:

(Ra) 10 KΩΩΩΩ

D2 IN4001

+VCC

(Rb)

D IN4001

1KΩΩΩΩ

B A

ASG Vi = 0.2 v

fi = 1 KHz -VCC VO to CRO

Fig (1):- Circuit Diagram of half wave rectifier circuit.

Waveform:

Vi

Volts

Vm

t

Vo

D2 on D1 on D2 on

Volts D1 off D2 off D1 off t

Transfer Characteristics:

Vo

Vi Vi

Transfer Characteristics

Fig (1a): Waveforms & Transfer Curve


12


PRECISIONPRECISIONPRECISIONPRECISION RECTIFIERSRECTIFIERSRECTIFIERSRECTIFIERS

Aim: To Rig Up And Test Half Wave and Full Wave Precision Rectifiers.

Apparatus Required:

IC741, Diodes, Resistors, ASG and probes, Base Board, Adopters & CRO, Digital Multimeter

(DMM) & Probes, Connecting wires and Power supply.

Procedure:

1. Connections are made as shown in the circuit of fig 1.

2. A signal generator is connected to the input. A sinusoidal input voltage of amplitude less than 0.7 V

with frequency of 1 KHz is applied and the input and output waveforms at points A & B are

observed on CRO.

3. The CRO is then set to X-Y mode and its transfer characteristics are observed.

4. The values of Ra and / or Rb are changed and change in the slope of transfer curve is observed.

5. The minimum input voltage, which can be rectified, is measured.

6. The step 2 to 5 is repeated for full wave rectifier circuits shown in fig 2.

Conclusion:

Result:

__________________

Staff Incharge

Assignments:

1. What are precision rectifiers?

2. Explain how cut in voltage is overcome in precision rectifiers?


13

Design:

Given A =R

Ra== 10

5.0

5

Assume R = 1KΩ ∴Ra = Rb = 10KΩ

The above design is applicable to half wave, full wave (positive precision & negative precision) rectifier.

b) Full Wave Precision Rectifier

Circuit Diagram (Positive Full Wave Rectifier Circuit):

(Ra) 10 k ΩΩΩΩ 10 k ΩΩΩΩ 10 kΩΩΩΩ

+Vcc +Vcc

1 kΩΩΩΩ IN4001

fI = 1KHz

VI = 0.2v

ASG IN4001 VO to CRO

-VCC -VCC

(Rb) 10 KΩΩΩΩ

Waveform:

Vi Vm

Volts t

Vo

Volts t

Waveforms & Transfer Curve

Vi -VI(max) VI (max) V


14

Circuit Diagram (Negative Full wave Rectifier Circuit):

(Ra) 10 k Ω 10 k Ω 10 kΩ

+Vcc +Vcc

IN4001

R=1KΩΩΩΩ

Fin =1 KHz

Vin = 0.2 V

IN4001 V0

ASG -VCC -VCC

Rb

Use Ra=Rb= 10 KΩΩΩΩ initially

Waveform:

Vm

Vi

Volts t

Vo

Volts t

Waveforms & Transfer Curve

Vo

Vi -VI(max) VI (max) Vi


15

CIRCUIT DIAGRAM: CIRCUIT DIAGRAM: CIRCUIT DIAGRAM: CIRCUIT DIAGRAM: ----

IIIIIIII----Order Active Low Pass FilterOrder Active Low Pass FilterOrder Active Low Pass FilterOrder Active Low Pass Filter

IIIIIIII----Order Active High PasOrder Active High PasOrder Active High PasOrder Active High Pas7777s Filters Filters Filters Filter

Design:Design:Design:Design:---- (LPF & HPF)(LPF & HPF)(LPF & HPF)(LPF & HPF)

Assume Pass band gain AAssume Pass band gain AAssume Pass band gain AAssume Pass band gain AVVVV = 2, Cutoff frequency f= 2, Cutoff frequency f= 2, Cutoff frequency f= 2, Cutoff frequency fCCCC = 5KHz= 5KHz= 5KHz= 5KHz

1.1.1.1. AmpliAmpliAmpliAmplifier: Afier: Afier: Afier: AVVVV = 1 + = 1 + = 1 + = 1 + R

Rf = 2, then Rf = R, choose Rf = R = 10K= 2, then Rf = R, choose Rf = R = 10K= 2, then Rf = R, choose Rf = R = 10K= 2, then Rf = R, choose Rf = R = 10KΩΩΩΩ

2.2.2.2. Filter Circuit : Cut off frequency fFilter Circuit : Cut off frequency fFilter Circuit : Cut off frequency fFilter Circuit : Cut off frequency fCCCC = = = = 112

1

CRππππ = 5KHz= 5KHz= 5KHz= 5KHz

Choose CChoose CChoose CChoose C1111 = 0.01= 0.01= 0.01= 0.01µµµµf then Rf then Rf then Rf then R1111 = 3.183 K= 3.183 K= 3.183 K= 3.183 KΩΩΩΩ ∼∼∼∼ 3.3 K3.3 K3.3 K3.3 KΩΩΩΩ


16

RRRRffff = 10K= 10K= 10K= 10KΩ, RΩ, RΩ, RΩ, R1111 = 3.3K= 3.3K= 3.3K= 3.3KΩ, CΩ, CΩ, CΩ, C1111 = 0.01= 0.01= 0.01= 0.01µµµµf, Opf, Opf, Opf, Op----amp = amp = amp = amp = µµµµA741A741A741A741


IIIIIIII –––– OrderOrderOrderOrder LowLowLowLow PassPassPassPass andandandand HighHighHighHigh PassPassPassPass ActiveActiveActiveActive FiltersFiltersFiltersFilters

AIM: AIM: AIM: AIM: ---- Design a second order Butterworth active low pass / high pass filter for a given cut-off

frequency fC = ______Hz. Conduct an experiment to draw frequency response and verify the

roll off.

PROCEDURE: PROCEDURE: PROCEDURE: PROCEDURE: ----

1. Connections are made as shown in the circuit diagram.

2. Apply sine wave i/p signal of peak amplitude 5 volts.

3. Check the gain of non-inverting amplifier by keeping the frequency of the input signal

in the pass band of the filter. Note down the output voltage VO max.

4. Keeping the input signal amplitude constant, vary the frequency until the output

voltage reduces to 0.707 Vo max, the corresponding frequency is the cut-off frequency

(fC) of the filter.

To find the To find the To find the To find the RRRRollollolloll----offoffoffoff factor factor factor factor ::::----

1. For LPF :- Keeping the input signal amplitude constant, adjust the input frequency at

10fC. Note down the output signal amplitude. The difference in the gain of the filter at

fC and 10fC gives the Roll-of factor.

2. For HPF :- Keeping the input signal amplitude constant, adjust the input frequency at

0.1fC, note down the output signal amplitude. The difference in the gain of the filter at

fC and 0.1fC gives the Roll-of factor.


17

Tabulation: Tabulation: Tabulation: Tabulation:

High Pass FilterHigh Pass FilterHigh Pass FilterHigh Pass Filter VVVVi pi pi pi p----pppp ==== Volts (Constant)Volts (Constant)Volts (Constant)Volts (Constant)

I/P frequency iI/P frequency iI/P frequency iI/P frequency in Hzn Hzn Hzn Hz O/P Voltage VO/P Voltage VO/P Voltage VO/P Voltage VO PO PO PO P----

PPPP (volts)(volts)(volts)(volts) Gain magnitude Gain magnitude Gain magnitude Gain magnitude

(Vo/Vi)(Vo/Vi)(Vo/Vi)(Vo/Vi) Gain magnitude in DBGain magnitude in DBGain magnitude in DBGain magnitude in DB

20log(Vo/Vi)20log(Vo/Vi)20log(Vo/Vi)20log(Vo/Vi)

Roll off = Roll off = Roll off = Roll off = ---- (G1 (G1 (G1 (G1 ---- G2) db/decade = G2) db/decade = G2) db/decade = G2) db/decade =

Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range of 1 Decade.of 1 Decade.of 1 Decade.of 1 Decade. Frequency ResponseFrequency ResponseFrequency ResponseFrequency Response for High Pass Filterfor High Pass Filterfor High Pass Filterfor High Pass Filter


18


19

Tabulation:Tabulation:Tabulation:Tabulation:

Low Pass FilterLow Pass FilterLow Pass FilterLow Pass Filter VVVVi pi pi pi p----pppp ==== Volts (Constant)Volts (Constant)Volts (Constant)Volts (Constant)

I/P frequency in HzI/P frequency in HzI/P frequency in HzI/P frequency in Hz O/P Voltage VO/P Voltage VO/P Voltage VO/P Voltage VO PO PO PO P----

PPPP (volts)(volts)(volts)(volts) Gain magnitude Gain magnitude Gain magnitude Gain magnitude

(Vo/Vi)(Vo/Vi)(Vo/Vi)(Vo/Vi) Gain magnitude in DBGain magnitude in DBGain magnitude in DBGain magnitude in DB

20log(Vo/Vi)20log(Vo/Vi)20log(Vo/Vi)20log(Vo/Vi)

Roll off = Roll off = Roll off = Roll off = ---- (G1 (G1 (G1 (G1 ---- G2) db/decade =G2) db/decade =G2) db/decade =G2) db/decade = Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range Note: The values of G1, G2 are determined from the Tabular Column over a frequency range of 1 Decade.of 1 Decade.of 1 Decade.of 1 Decade. Frequency Response for Low Pass FilterFrequency Response for Low Pass FilterFrequency Response for Low Pass FilterFrequency Response for Low Pass Filter

ConclusionConclusionConclusionConclusion::::

Result:Result:Result:Result:

__________________

Staff Incharge

AssignmentAssignmentAssignmentAssignment

1. WhatWhatWhatWhat are are are are filters?filters?filters?filters? 3.3.3.3. Compare Active and passive filters.Compare Active and passive filters.Compare Active and passive filters.Compare Active and passive filters.

2. List the type of List the type of List the type of List the type of filters?filters?filters?filters? 4. 4. 4. 4. Define low pass & Define low pass & Define low pass & Define low pass & highhighhighhigh pass filterpass filterpass filterpass filters.s.s.s.


20


IIIIIIII----Order Active Band Pass FilterOrder Active Band Pass FilterOrder Active Band Pass FilterOrder Active Band Pass Filter

Design:Design:Design:Design:

Specifications:Specifications:Specifications:Specifications:

Pass band gain AV = 1.586, cut -off frequency fH = 5 KHz, fL=8 KHz, BW= 3 KHz

1. Amplifier:1. Amplifier:1. Amplifier:1. Amplifier:

Voltage gain AV = 1 + Rf / R = 1.586, choose R = 10KΩ,

Then Rf = 5.86 kΩ (use 5.6 kΩ+ 220 Ω std value)

2. Filter:2. Filter:2. Filter:2. Filter:

Cut - off frequency fH= 1/2π R2C2= 5 KHz, Choose C2= 0.01µf, then R2 = 3.183 kΩ (Select R2 = 3.3 kΩ)

Cut - off frequency fL = 1/2π R1 C1 = 8 k Hz, Choose C1= 0.01µf, then R1= 1.989 k Ω (Select R1 = (1.5 kΩ +

470Ω))


21

Experiment Experiment Experiment Experiment No:No:No:No: 6666 DATE: DATE: DATE: DATE: __/__/______/__/______/__/______/__/____

IIIIIIII –––– OrderOrderOrderOrder BandBandBandBand PassPassPassPass ActiveActiveActiveActive FiltersFiltersFiltersFilters

AIM: AIM: AIM: AIM: ---- Design a second order band pass and band stop active filter for a given frequencies fC1

= ______Hz and fC2 = ______Hz. Conduct an experiment to draw frequency response and verify

the Roll off (Band Width = 3 to 5 KHz).

PROCEDURE: PROCEDURE: PROCEDURE: PROCEDURE: ----

1. Connections are made as shown in the circuit diagram.

2. Apply sine wave i/p signal of peak amplitude 5 volts.

3. Check the gain of non-inverting amplifier by keeping the frequency of the input signal

in the pass band of the filter. Note down the output voltage VO max.

4. Keeping the input signal amplitude constant, vary the frequency on either side of pass

band until the output voltage reduces to 0.707 Vo max, the corresponding frequencies

are the lower cut-off frequency (fL) and the upper cut-off frequency (fH) of the filter.

To find the To find the To find the To find the RRRRollollolloll----offoffoffoff factor factor factor factor ::::----

1. For LPF :- Keeping the input signal amplitude constant, adjust the input frequency at

10fC, note down the output signal amplitude. The difference in the gain of the filter at

fC and 10fC gives the Roll-of factor.

2. For HPF :- Keeping the input signal amplitude constant, adjust the input frequency at

0.1fC, note down the output signal amplitude. The difference in the gain of the filter at

fC and 0.1fC gives the Roll-of factor.


22

Tabulation:Tabulation:Tabulation:Tabulation:

Band Pass FilterBand Pass FilterBand Pass FilterBand Pass Filter VVVVi pi pi pi p----pppp ==== Volts (Constant)Volts (Constant)Volts (Constant)Volts (Constant)

Frequency HzFrequency HzFrequency HzFrequency Hz O/P Voltage VO/P Voltage VO/P Voltage VO/P Voltage VO PPO PPO PPO PP (volts)(volts)(volts)(volts) Gain (Vo/Vi)Gain (Vo/Vi)Gain (Vo/Vi)Gain (Vo/Vi) Gain in DB Gain in DB Gain in DB Gain in DB 20 log (Vo/Vi)20 log (Vo/Vi)20 log (Vo/Vi)20 log (Vo/Vi)


23

Frequency Response Frequency Response Frequency Response Frequency Response for Band Pass Filterfor Band Pass Filterfor Band Pass Filterfor Band Pass Filter

ConclusionConclusionConclusionConclusion::::

Result:Result:Result:Result:

__________________

Staff Incharge

Assignments:

1. Define a) BPF

b) BEF

c) Roll off


24

d) Bandwidth

e) Stop band

f) Pass band


TTTT----Type AttenuatorType AttenuatorType AttenuatorType Attenuator ππππ----Type AttenuatorType AttenuatorType AttenuatorType Attenuator

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