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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
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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
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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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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
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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
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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
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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 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
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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
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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
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CONCLUSION:
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Electric Filters Biquad Circuit(B.P)NED University of Engineering and Technology Department of Electrical Engineering
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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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Electric Filters Biquad Circuit(B.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(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
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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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Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering
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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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Electric Filters Biquad Circuit(B.S)NED University of Engineering and Technology Department of Electrical Engineering
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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
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CONCLUSION:
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Electric Filters Biquad Circuit(H.P)NED University of Engineering and Technology Department of Electrical Engineering
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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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Electric Filters Biquad Circuit(H.P)NED University of Engineering and Technology Department of Electrical Engineering
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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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Electric Filters Biquad Circuit(H.P)NED University of Engineering and Technology Department of Electrical Engineering
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CALCULATIONS:
Element values obtained
C1 = R4 =C2 = R5 =
R1 = R2 =R3= R6=
R7=R8 = R9=R10=
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Electric Filters Biquad Circuit(H.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(H.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(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
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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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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
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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
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Electric Filters Design of TREBLE control NED University of Engineering and Technology Department of Electrical Engineering
CIRCUIT DIAGRAM