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Ee-315 Electric Filter _2011

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    PRACTICAL WORK BOOKFor Academic Session 2011

    ELECTRIC FILTERS (EE-315)For

    T.E (EE) & T.E (TC)

    Name:

    Roll Number:

    Class:

    Batch: Semester/Term:

    Department :

    Department of Electrical EngineeringNED University of Engineering & Technology

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    Electric Filters ContentsNED University of Engineering and Technology Department of Electrical Engineering

    Revised 2011MMAB

    CONTENTS

    Lab.

    No.

    Da te d

    List of Experiments

    Pa ge

    No .

    Re ma rk s

    1Introduction to filters

    1

    2To investigate inverting and non-

    inverting configurations of OP-AMP7

    3To investigate the Frequency response of

    741 OP-AMP in close-loop11

    4To implement First order low pass active

    filter17

    5 To implement First order High passactive filter

    23

    6 To implement higher order filters usingcascade connection.

    29

    7 To obtain low pass response usingBiquad circuit

    35

    8 To obtain band pass response using

    Biquad circuit

    41

    9 To obtain high pass response usingBiquad circuit

    47

    10 To obtain band stop response usingBiquad circuit

    53

    11 To implement Generalized impedanceconverter circuit.

    59

    12 Demonstration of a voice processingMATLAB based program.

    65

    13LAB PROJECT(a)

    To design and implement BASS control

    circuit.67

    14LAB PROJECT(b)

    To design and implement MID control

    circuit.70

    15LAB PROJECT(c)

    To design and implement TREBLE

    control circuit.

    73

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    1

    LAB SESSION 01

    Introduction to Filters

    (Design Terminologies)OBJECTTo familiarize with the basic filter terminologies and understand the behavior of basic

    filters circuits.

    APPARATUSBread-board, 1K resistor, 0.1F capacitor, Oscilloscope and a function generator.

    THEORY

    Electric filters as the name implies are circuits capable to allow or reject signals. Thedecision of accepting or rejecting a signal is based on its frequency. The basic idea

    behind filter theory is that in time domain a single non-sinusoidal periodic signal iscomposed of an infinite number of sinusoids and using filter circuits we may select a

    desired frequency signal. The idea is illustrated below

    Consider a signal shown in figure (1).

    The signal is composed of threedifferent frequencies each of different

    magnitude. The component signals are

    shown subsequently in figure (2).

    Normally the signal we encounter is intime domain, which is the sum of

    other signals of different frequencies.

    The component signals cant be

    extracted directly, since they all add

    up at a single instant of time. Whereasin frequency domain these signals are treated as separate signals , so we design

    circuits that could handle frequency based characteristic of the signals . Processing the

    resultant signal can lead us to any of the desired component.

    Fig 1

    Fig 2

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    2

    Signal Source

    R

    L

    Filter design PhilosophyAs mentioned above we design our system based on the information of signal

    frequencies. Design approach is simple; we have certain known ranges of input signals

    that contain the required signal. In short, we know system input and output. Based on

    the frequency information we select our system components. Its obvious to expect that

    our circuit have frequency dependent elements.Note: we dont cut other signals from the input signal in filters. We just suppress them

    and amplify the desired frequency.

    Based on this information lets discuss frequency response of a simple RL circuit.

    Consider that we have a signal source that contains number of frequency components.

    As mentioned previously, every frequency is treated separately in frequency domain. If

    we take the output across the inductor, inductor will behave short circuited for the low

    frequency signals, hence lower frequency will be by passed by the inductor. Whereas

    inductor wont bypass high frequency signals (open circuited for high frequencies) andtheir magnitude wont decrease at the output terminal. Since the circuit wont let low

    frequencies to propagate at the output and allows only high frequencies, it is a HIGHPASS filter circuit. The output signal will be a processed high frequency signal with

    little low frequency components.

    The frequency response of the typical HIGH PASS circuit is shown below. Themagnitude of low frequency signal is smaller than the high frequency signal.

    Lets define certain terminologies to describe frequency response of the system.

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    3

    Design Terminologies

    Pass Band:

    The range of frequencies at which the output is little attenuated is called as pass band.

    We shall treat these signals as the accepted signals.

    Stop Band:The range of frequencies at which the output is significantly attenuated is called as stop

    band. We shall treat these signals as rejected signals or unwanted signals.

    Cutoff Frequency:The frequency associated with the boundary between stop band and an adjacent pass

    band is called as the cutoff frequency. It is the frequency at which the output is 0.707

    times the maximum value in the pass band.

    Lets review the plot in terms of these definitions

    Besides HIGH PASS filters, we have LOW PASS, BAND PASS and BAND STOP

    filters. We shall study each response in detail. Right now lets consider another filter

    circuit based on RC circuit . You are required to plot the frequency response for the

    circuit, and determine the cutoff frequency of your circuit.

    Stop

    Band PASS BAND

    Cutofffrequency

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    4

    CIRCUIT DIAGRAM

    PROCEDURE Set the function generator to sinusoidal function with peak value of 1 volt

    Connect the circuit elements as shown in the above diagram

    Vary the frequency of the function generator from 100Hz to 2000Hz and

    measure the peak values of the output signal form oscilloscope.

    OBSERVATIONSBased on the observations, plot the magnitude of output signal against their

    corresponding frequencies. Also predict the cutoff frequency of the response. Can youname this filter?

    S. No Frequency(Hz) Output Voltage(Peak)

    01 100

    02 200

    03 400

    04 600

    05 800

    06 1000

    07 120008 1400

    09 1500

    10 1600

    11 1800

    12 2000

    XFG1

    C1

    0.1uF

    R1

    1k

    2

    XSC1

    A B

    Ext Trig+

    +

    _

    _ + _

    1

    0

    0

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    5

    Plot

    1.00

    0.95

    0.90

    0.85

    0.80

    0.75

    0.70

    0.65

    0.60

    0.55

    0.50

    0.45

    0.40

    0.35

    0.30

    0.25

    0.20

    0.15

    0.10

    0.05

    0.00 0 200 400 600 800 1000 1200 1400 1600 1800 2000

    Gain

    Frequency in Hz

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    Electric Filters Introduction to FiltersNED University of Engineering and Technology Department of Electrical Engineering

    6

    CONCLUSION:

    The above characteristics shows that the circuit is a , with a

    cutoff frequency of Hz.

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    Electric Filters Operational AmplifiersNED University of Engineering and Technology Department of Electrical Engineering

    7

    LAB SESSION 02

    Operational Amplifiers

    OBJECT

    To investigate the inverting and non-inverting mode of Op-amp(741-IC)

    APPARATUS

    Bread-board, 10 K resistors, Dual Power supply, multi-meter and a 714 Op-amp IC.

    THEORY

    Operational amplifiers are voltage controlled voltage sources. They differ from ordinary

    amplifiers by having two inputs. The operation is such that the output voltage is thedifference of the two input voltages multiplied by an overall gain factor. A typical circuit

    diagram of an ideal Op-amp is shown below

    )( vvAvo

    v-

    v+

    A

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    Electric Filters Operational AmplifiersNED University of Engineering and Technology Department of Electrical Engineering

    8

    The 741 Operational amplifier exhibits ideal behavior for D.C signals, the behavior

    deviates as the frequency of the signal exceeds audio range. The specifications along

    with the pin diagram of a typical 741 are shown below

    SYMBOL VARIABLE VALUE UNIT

    A Open loop gain 210 5

    Ri Input Resistance 2106

    Ro Output Resistance 75

    Vos Input offset voltage 0.001 V

    Ibs Input bias current 8108 A

    SR Slew Rate 5105

    V/s

    Cc Compensation Capacitance 31011 F

    PIN CONFIGURATION OF 741-IC

    Pin number 2 and 3 are the two input terminals, where as pin number 6 is the output pin.

    We connect positive and negative supply voltages to pin number 7 and 4 respectively.

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    Electric Filters Operational AmplifiersNED University of Engineering and Technology Department of Electrical Engineering

    9

    CIRCUIT DIAGRAMS

    Inverting Mode:In inverting mode input is connected to the inverting terminal of op-amp, as shown in

    the circuit diagram. The gain for the inverting mode is

    i

    f

    R

    RGain

    OBSERVATIONS

    Rf R i Vin Vo(expected) Vo(measured) Error20K 10K 2V

    U1

    741

    3

    2

    4

    7

    6

    51

    PositiveSupply

    10V

    NegativeSupply

    -10V

    V1

    2 V

    Ri

    10kOhm

    Rf

    20kOhm

    XMM1

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    Electric Filters Operational AmplifiersNED University of Engineering and Technology Department of Electrical Engineering

    10

    Non-inverting Mode:

    In non-inverting mode input is connected to the non-inverting terminal of op-amp, as

    shown in the circuit diagram. The gain for the non-inverting mode is

    i

    f

    R

    RGain 1

    This shows that the gain of the non-inverting configuration can never be less than 1.

    OBSERVATIONS

    Rf R i Vin Vo(expected) Vo(measured) Error

    20K 10K 2V

    CONCLUSION:

    U1

    741

    3

    2

    4

    7

    6

    51

    V1

    2 VRi

    10kOhm

    PositiveSupply

    10V

    NegativeSupply

    -10V

    U2

    20kOhm

    XMM1

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    11

    LAB SESSION 03

    Frequency Response of 741 Op-amp

    OBJECTTo investigate the Frequency response of 741 OP-AMP in close-loop

    APPARATUSBread-board, 10K resistor, 100K resistor, dual power supply, multi-meter and a 714

    Op-amp IC.

    THEORY

    Most of the times, for the sake of simplicity we design filter circuits using ideal model ofOp-amp. The ideal model suggests that Op-amp has an infinite open loop gain for all

    frequencies i.e. op-amp gain is independent of frequency. In the real devices such as 741

    we have a small integrated capacitor, for the reason of stability, which introduces a low

    frequency dominant pole in the open loop transfer function. A typical expression for the

    open loop gain is shown below. The expression and the plot show that the gain isfrequency dependent. As we increase the frequency of the signal the gain of op-amp

    reduces.

    )1028.17)(4.31(

    1028.17)(

    6

    12

    sssA

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    12

    Using op-amp in closed loop, we may reduce the gain of the amplifier and can achieve

    more bandwidth over which the gain remains constant. Its a kind of trade off between

    gain and bandwidth since the product of gain bandwidth for any device remains

    constant. For lower values of gain i.e. from 1 to 10 741 ICcan be used for audio range

    signals. If you want more gain, you have to cascade lower gain stages.

    CIRCUIT DIAGRAMS

    Low Gain, Higher Bandwidth(a)

    741IC

    Ri

    10kOhm

    Rf

    10kOhm

    XFG1

    XSC1

    A B

    G

    T

    High Gain, Lower Bandwidth(b)

    741IC

    Ri

    10kOhm

    Rf

    10kOhm

    XFG1

    XSC1

    A B

    G

    T

    100

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    13

    OBSERVATIONSFor circuit (a)

    For circuit (b)

    S. No Frequency Hz Gain = Vout/ Vin

    01 20002 1000

    03 2000

    04 4000

    05 6000

    06 8000

    07 10,000

    08 12,000

    09 14,000

    10 16,000

    11 18,000

    12 20,000

    13 24,000

    14 30,000

    15 50,000

    16 100,000

    S. No Frequency Hz Gain = Vout/ Vin200

    1000

    2000

    4000

    6000

    8000

    10,000

    12,000

    14,000

    16,00018,000

    20,000

    24,000

    30,000

    50,000

    100,000

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    14

    Plot (a)

    Frequency in Hz

    Gain

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    15

    Plot (b)

    Frequency in Hz

    Gain

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    Electric Filters Frequency Response of Op-ampNED University of Engineering and Technology Department of Electrical Engineering

    16

    CONCLUSION:

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    17

    LAB SESSION 04

    First order Low pass FilterOBJECTTo design and investigate the response of 1

    storder low pass filter (active)

    APPARATUSBread-board, pair of resistances and a pair of capacitances, Oscilloscope, function

    generator, dual power supply and 741 op-amp IC

    THEORY

    A typical bilinear transfer function contains single pole and zero.

    )(

    )()(

    ps

    zsKsT

    Where K is the over-all gain of the system and z and p represents pole and zero. In order

    to achieve a low pass responsez > p

    A typical response of the system can be shown as

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    18

    Design Activity

    With the help of admittance or impedance model of inverting configuration of op-amp

    we can achieve the above form of transfer function

    The circuit is shown below

    The transfer function obtained through this circuit is given as

    )(

    )()(

    22

    11

    2

    1

    GsC

    GsC

    Y

    YsT

    Show all the design steps on the next page, for the following design parameters and

    implement the circuit.

    K =

    z =

    =

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    19

    Calculations:

    Based on the design parameters the elements values obtained are

    C1 =C2 =

    R1 =

    R =

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    20

    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    21

    Plot

    Frequency in Hz

    Gain

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    ectric Filters First order low passNED University of Engineering and Technology Department of Electrical Engineering

    22

    CONCLUSION:

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    23

    LAB SESSION 05

    First order High pass FilterOBJECTTo design and investigate the response of 1

    storder High pass filter (active)

    APPARATUSBread-board, pair of resistances and a pair of capacitances, Oscilloscope, function

    generator, dual power supply and 741 op-amp IC

    THEORY

    A typical bilinear transfer function contains single pole and zero.

    )(

    )()(

    ps

    zsKsT

    Where K is the over-all gain of the system and z and p represents pole and zero. In order

    to achieve a High pass responsep > z

    A typical response of the system can be shown as

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    24

    Design Activity

    With the help of admittance or impedance model of inverting configuration of op-amp

    we can achieve the above form of transfer function

    The circuit is shown below

    The transfer function obtained through this circuit is given as

    )(

    )()(

    22

    11

    2

    1

    GsC

    GsC

    Y

    YsT

    Show all the design steps on the next page, for the following design parameters and

    implement the circuit.

    K =

    z =

    =

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    25

    CALCULATIONS:

    Element values obtained

    C1 =

    C2 =

    R1 =

    R2 =

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    26

    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    27

    Plot

    Frequency in Hz

    Gain

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    Electric Filters First order High passNED University of Engineering and Technology Department of Electrical Engineering

    28

    CONCLUSION:

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

    29

    LAB SESSION 06

    Cascade DesignOBJECTTo implement higher order filters using cascade connection.

    APPARATUSBread-board, pair of resistances and a pair of capacitances, Oscilloscope, function-

    generator, dual power supply and two 741 op-amp ICs

    THEORY

    Higher order filter circuits can be implemented using 1st order circuits connected in a

    chain, so called cascade connection. A cascaded system is a system that consists ofsmall subsystems such that the output of one subsystem is the input of the other . A

    simple cascade connection block diagram is shown below

    Where T(s) is the system overall transfer functionUsing cascade connection, we can achieve band pass and band stop response since they

    cant be implemented form a 1st order system. Cascading a low pass and a high pass

    can provide these responses. However there are some conditions which we have to

    satisfy before obtaining the over-all response i.e. no subsystem in the cascade

    connection is going to load other subsystem . We shall implement a band pass responsewith the help of 1st order filter circuits.

    T2T1 T3

    T(s) = (T1)(T2)(T )

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

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    CIRCUIT DIAGRAM

    The circuit diagram shown above consists of two cascaded bilinear systems with the

    overall system function of

    )(

    )(

    )(

    )()(

    44

    33

    22

    11

    GsC

    GsC

    GsC

    GsCsT

    Now select the element values to achieve the following system function

    )22000(

    )28000(

    )2500()(

    s

    s

    s

    ssT

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

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    CALCULATIONS:

    Element values obtained

    C1 = C3 =C2 = C4 =

    R1 = R3 =

    R2 = R4 =

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

    33

    Plot

    Frequency in Hz

    Gain

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    Electric Filters Cascade designNED University of Engineering and Technology Department of Electrical Engineering

    34

    CONCLUSION:

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

    35

    LAB SESSION 07

    Biquad Circuit (Low pass response)OBJECTTo design and investigate low pass response using Biquad circuit

    APPARATUSBread-board, resistors, capacitors, Oscilloscope, function-generator, dual power supply

    and three 741 op-amp ICs

    THEORY

    Biquad circuit is also known as Universal filter. We can implement low pass, band

    pass, high pass and band stop, 2nd order filters using biquad circuit. Dealing with thesecond order circuits we normally express system response in terms of gain (H),

    quality factor (Q) and resonance frequency (o).

    While designing low pass filter we keep the quality of the system less than 1, so that

    the response curve wont be peaky. This ensures that the system treat all the pass band

    signals equally.

    Following are some example response for Q = 7 (Fig 1) and Q = 0.8 (Fig 2).

    Fig 1 Fig 2

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

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    CIRCUIT DIAGRAM

    Since the output at the last stage is the product of the transfer functions of the sub-

    stages, the output equation can be given as

    5

    6

    2411

    2

    11

    3

    )()( R

    R

    CR

    s

    GsC

    GV

    GsC

    GVV

    oin

    o

    Starting from the above equation reduce the equation to a simplified Low pass function

    and compare it to the standard form i.e.

    22

    2

    )/()(

    oo

    o

    sQs

    HsT

    Also determine the element values for the following given system parameters

    Given data

    o =H =

    Q =

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

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    CALCULATIONS:

    Element values obtained

    C1 = R3 =C2 = R4 =

    R1 = R5 =

    R2 = R6=

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

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    Plot

    Frequency in Hz

    Gain

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    Electric Filters Biquad Circuit(L.P)NED University of Engineering and Technology Department of Electrical Engineering

    40

    CONCLUSION:

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    Electric Filters Biquad Circuit(B.P)NED University of Engineering and Technology Department of Electrical Engineering

    41

    LAB SESSION 08

    Biquad Circuit (Band pass response)OBJECTTo design and investigate band pass response using Biquad circuit

    APPARATUSBread-board, resistors, capacitors, Oscilloscope, function-generator, dual power supply

    and three 741 op-amp ICs

    THEORY

    We shall now implement band pass response using biquad circuit. Unlike low pass

    response, here, we shall keep the quality factor high. Increasing the quality factor forband pass response will increase the selectivity of a particular frequency.

    Following are some example response for Q = 7 (Fig 1) and Q = 1.0 (Fig 2).

    Fig 1 Fig 2

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    Electric Filters Biquad Circuit(B.P)NED University of Engineering and Technology Department of Electrical Engineering

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    CALCULATIONS:

    Element values obtained

    C1 = R3 =C2 = R4 =

    R1 = R5 =

    R2 = R6=

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    Electric Filters Biquad Circuit(B.P)NED University of Engineering and Technology Department of Electrical Engineering

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Plot

    Frequency in Hz

    Gain

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    Electric Filters Biquad Circuit(B.P)NED University of Engineering and Technology Department of Electrical Engineering

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    CONCLUSION:

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    Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering

    47

    LAB SESSION 09

    Biquad Circuit (Band Stop response)OBJECTTo design and investigate Band stop response using Biquad circuit

    APPARATUSBread-board, resistors, capacitors, Oscilloscope, function-generator, dual power supply

    and four 741 op-amp ICs

    THEORY

    We shall now implement band stop response using biquad circuit. Unlike low pass

    response, here, we shall keep the quality factor high. Increasing the quality factor forband stop response will increase the selectivity of a particular frequency.

    Following are some example response for Q = 7 (Fig 1) and Q = 1.0 (Fig 2).

    Fig 1 Fig 2

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    CIRCUIT DIAGRAM

    For band stop response we have added another op-amp to the previous circuit which isadding the input and the band pass response and equated the two resistances i.e. R1=R3

    )( .PBino VVV

    Starting from the above equation reduce the equation to a simplified Band stop function

    and compare it to the standard form of the band stop response i.e.

    22

    22

    )/()(

    oo

    o

    sQs

    ssT

    Also determine the element values for the following given system parameters

    Given data

    o =

    H = 1/Q

    Q =

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    CALCULATIONS:

    Element values obtained

    C1 = R4 =C2 = R5 =

    R1 = R6=

    R2 =R3= R7=R8 = R9=

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    Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering

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    Plot

    Frequency in Hz

    Gain

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    Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering

    52

    CONCLUSION:

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    Electric Filters Biquad Circuit(H.P)NED University of Engineering and Technology Department of Electrical Engineering

    53

    LAB SESSION 10

    Biquad Circuit (High Pass response)OBJECT

    To design and investigate High pass response using Biquad circuit

    APPARATUS

    Bread-board, resistors, capacitors, Oscilloscope, function-generator, dual power supplyand four 741 op-amp ICs

    THEORY

    We shall now implement High pass response using biquad circuit. In designing High

    pass filter we keep the quality of the system less than 1, so that the response curve

    wont be peaky. This ensures that the system treat all the pass band signals equally.

    Following are some example response for Q = 3 (Fig 1) and Q = 0.8 (Fig 2).

    Fig 1 Fig 2

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    CIRCUIT DIAGRAM

    For High pass response we have added another op-amp to the three op-amp biquad

    circuit which is adding the input, the band pass response and the low pass response. Wehave also equated the three resistances i.e. R3=R1=R2

    )( .. PLPBino VVVV

    Starting from the above equation reduce the equation to a simplified High pass function

    and compare it to the standard form of the High pass response i.e.

    22

    2

    )/()( oo sQs

    s

    sT

    Also determine the element values for the following given system parameters

    Given data

    o =

    Q =

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    CALCULATIONS:

    Element values obtained

    C1 = R4 =C2 = R5 =

    R1 = R2 =R3= R6=

    R7=R8 = R9=R10=

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Plot

    Frequency in Hz

    Gain

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    Electric Filters Biquad Circuit(H.P)NED University of Engineering and Technology Department of Electrical Engineering

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    CONCLUSION:

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

    59

    LAB SESSION 11

    Generalized Impedance ConverterOBJECT

    To simulate inductance using a generalized impedance converter circuit

    APPARATUS

    Bread-board, resistors, capacitors, Oscilloscope, function-generator, dual power supplyand a pair of 741 op-amp ICs

    THEORY

    The elements we discussed so far for the implementat ion of active filters were

    capacitors, resistors and op-amps. We havent discussed any approach which includes

    inductor in active circuit. The reason of not using inductors is that they require more

    space, since the dimension of an inductor is proportional to its inductance and for lower

    frequencies we need higher inductance values to achieve considerable impedance. Theother reason is that due to flux linkages, they could induce voltages to the adjacent

    elements.

    We can simulate inductance through alternate method, since the design approach for

    the passive network is simpler than the active approach.

    Consider a passive circuit, shown below. The response across the resistor will be a

    band pass. To simulate inductance we shall use a GIC circuit, which will convert a

    resistance into an inductance

    Signal Source

    R

    L

    C

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

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    CIRCUIT DIAGRAM OF GIC

    The relationship between Zin and Z can be given as

    ZZZ

    ZZZ

    in

    42

    31

    With the help of GIC circuit, implement a series RLC circuit with the following values

    and obtain response curve across the resistor.

    1 Z3Z2

    ZZin

    Element values of the passive circuit

    C = 1FR = 10K

    L = 1mH

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

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    CALCULATIONS:

    Element values obtained

    Z =Z1 =

    Z2 =

    Z3 =

    Z4 =

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

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    OBSERVATIONS

    Now based on your circuit design, select suitable range of frequencies for the input

    signal and obtain the gain for every frequency. Also plot the gain against frequency.

    S. No Frequency Hz Gain = Vout/ Vin db Gain

    01

    02

    03

    04

    05

    06

    07

    08

    09

    10

    11

    12

    13

    14

    15

    16

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

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    Plot

    Frequency in Hz

    Gain

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    Electric Filters GIC circuitNED University of Engineering and Technology Department of Electrical Engineering

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    CONCLUSION:

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    Electric Filters Voice Processing Using MatlabNED University of Engineering and Technology Department of Electrical Engineering

    65

    LAB SESSION 12

    Voice Processing Using MatlabOBJECT

    To implement a transfer function over voice signal and observe its output generated byMATLAB.

    APPARATUS

    MATLAB software

    OVERVIEW OF MATLAB AND RELATED TOOL BOXES

    It will be covered by the instructor during the Lab session.

    MAIN PROGRAM

    Our main simulation can be divided into three main blocks

    Input/output block Transfer function DAC/ADC

    BASS CONTROL MODULE

    Speaker

    OutputInput

    10

    Gain1From Mic

    In1 Out1

    DAC

    300*2*pi

    s+300*2*pi

    BASS

    In1 Out1

    ADC

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    Electric Filters Voice Processing Using MatlabNED University of Engineering and Technology Department of Electrical Engineering

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    The input/output blocks are MIC and speaker taken from Signal Processing Block Set.

    These modules allow us to obtain voice signals directly from the MIC and to reproduce it

    through speakers after processing the signal. Our processing will be a real-time

    processing. These modules work for digital signals only. The output of MIC and the

    input of speaker are in digital form, where as s-domain transfer function requirescontinuous-time signal. In order to achieve compatibility among the blocks we have

    added DAC (digital to analog) and ADC (analog to digital) converters. You may create

    any transfer function for your voice signal of range (20 to 5000 Hz). You need a faster

    processor for the signal beyond this range.In our case, a low pass filter is implemented. When you simulate the program you can

    feel the difference in the input and output voice. The low pass will reduce the sharp

    contents of voice. Mean while the scopes connected to the input and output sides also

    provides you an opportunity to view the modification that took place during the

    processing in the voice signal. High frequency components will be reduced and theoutput wave form will be a smoother one. A sample input and its output is shown below

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    Electric Filters Design of BASS control NED University of Engineering and Technology Department of Electrical Engineering

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    LAB SESSION 13

    Design Bass Control CircuitOBJECT

    Design and implement bass control circuit

    EXPLANATION

    BASS CONTROL provides boost to low frequency notes of audio signal such as beat. It

    is a low pass filter and process audio signals of range 20 to 300 Hz (approx). Most of thelow frequency sound lies in this region. Low frequency notes are power hunger and need

    more power than other range of audio signals. At the output stage of BASS circuit an

    especially designed transducer Woofer is connected.

    You need an audio input that must contain sound of lower notes to process this signal.The Bass control circuit wont allow or significantly suppress signals ranging form 301

    to 20KHz.

    Based on the necessary design procedures, select your circuit elements and mention all

    the calculations and assumptions below.

    CALCUALTIONS

    BODE PLOT

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    CIRCUIT DIAGRAM

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    Electric Filters Design of MID control NED University of Engineering and Technology Department of Electrical Engineering

    70

    LAB SESSION 14

    Design MID Control CircuitOBJECT

    Design and implement Mid control circuit

    EXPLANATION

    MID CONTROL provides boost to voice frequency notes of audio signal. It is a Band

    pass filter and process audio signals of range 300 to 4000 Hz (approx).

    You need an audio input that must contain voice of human to process. The Mid control

    circuit wont allow or significantly suppress signals ranging form 20 to 300 Hz and from4001 to 20KHz.

    Based on the necessary design procedures, select your circuit elements and mention all

    the calculations and assumptions below.

    CALCUALTIONS

    BODE PLOT

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    Electric Filters Design of MID control NED University of Engineering and Technology Department of Electrical Engineering

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    CIRCUIT DIAGRAM

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    Electric Filters Design of TREBLE control NED University of Engineering and Technology Department of Electrical Engineering

    73

    LAB SESSION 15

    Design Treble Control CircuitOBJECT

    Design and implement Treble control circuit

    EXPLANATION

    TREBLE CONTROL provides boost to high frequency notes of audio signal. It is a high

    pass filter and process audio signals of range 4001 to 20000 Hz (approx).

    You need an audio input that must contain sharp sounds. The Mid control circuit wont

    allow or significantly suppress signals ranging form 20 to 4000 Hz. The output isconnected to an especially designed transducer named as TWEETER

    Based on the necessary design procedures, select your circuit elements and mention all

    the calculations and assumptions below.

    CALCUALTIONS

    BODE PLOT

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    Electric Filters Design of TREBLE control NED University of Engineering and Technology Department of Electrical Engineering

    CIRCUIT DIAGRAM