A203SE Analog Electronics Coursework

7/30/2019 A203SE Analog Electronics Coursework

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BADURDEEN SHAKEAL 1

AUSTONINSTITUTE OF MANAGEMENT CEYLON

Faculty of Engineering

Advanced Diploma in Electrical and Electronics Engineering

A203SE Analogue Electronics

Coursework

Student Name: Badurdeen Shakeal

Student ID: T1-11-EEE-L2-86

Supervisor: Dr. Rohan Munasinghe

Submission Date: 2012.05.30


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BADURDEEN SHAKEAL 2

PROJECT/ASSIGNMENT SUBMISSION ACKNOWLEDGEMENT SLIP

Name of Student: M.Badurdeen Shakeal Student No: aimc260211/86 T1-11-EEE-L2-86

Home Address: No.2/154, Sejiah Zone. Panavitiya, Deekirikewa, 60123, Sri Lanka

Date of Submission: 03th of May 2012 Name of Tutor: Dr. Rohan Munasinghe

Program/ Module: A203SE (Analog Electronics)

Received By: _________________________ Date: ___________________________________

Individual Projects (50%)

Marks

Learning Outcome Weightage 1st marker2nd marker/

moderator

Final mark

1. State the limitations of voltage operational amplifiers and

predict how these limitations affect performance.

P1:

Schematic diagrams Multisim simulations Analysis/ Discussion

25%

5%

10%

10%


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2 Extend the application of voltage amplifiers into areas

such as instrumentation, filters, oscillators and non-linear

circuits.

P2:

Schematic diagrams Design Calculation Multisim simulation Analysis/ Discussion

35%

5%

15%

10%

5%

3. Analyse transistor amplifiers using small signal models.

P3 :

Schematic diagrams Design Calculation and bandwidth plot Multisim simulation Analysis/ Discussion

30%

5%

12%

8%

5%

Quality and structure of the report 10%

Total Marks 100%

1stmarkers comment

_______________________________________________________________________________________

_________________________________________________________________________________________

_________________________________________________________________________________________________

2ndmarkers/ moderator comment

_______________________________________________________________________________________

_________________________________________________________________________________________

_________________________________________________________________________________________________


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Table of Contents

1. Declaration of originality. 012. Abstract. 023. Introduction.. 034. Solution for problem one (offset voltage characteristics of an operating amplifier)

4.1. Offset of AD741H Op-Amp ........ 064.2. Offset of AD707AR Op-Amp ......................................... 084.3. Offset of AD743KR Op-Amp ...104.4. Reduce offset voltage using Method 01... 124.5. Reduce offset voltage using Method 02... 134.6. Reduce offset voltage using Method 03... 14

5. Designing of an active crossover filter5.1. About active crossover filter. 17

5.2. Calculations....19

5.3. Multisim diagrams..... 21

6. Implementation of two stage BJT amplifier.6.1. Basic diagram of BJT transistor........ 23

6.2. Design Implementation and Calculations .24

6.3. Calculation stage two low frequency part .... 25

6.4. Calculation stage two high frequency part ....29

6.5. Total circuit component chart....... 31

6.6. Multisim simulations..... 31

7. Critical analysis7.1. Discussions and comparisons of results 33

8. Conclusions....339. Reference... 34


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BADURDEEN SHAKEAL 5

1. Declaration of Originality

I am aware of and understand the universitys policy on plagiarism and I certify that this

coursework is my own work, expert where indicated by referencing, and that I have followed the

good academic practice.

Signature: __________________ Date: 30th may 2012


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2. Abstract

This A203SE Analogue Electronics module course work has three main parts. The first part is

analyzing the effect of offset voltage rating in the output of an operational amplifier. Using the NI

Circuit Suits Multisim software designed and simulated three different operating amplifiers with

three different offset voltage rating and calculated output of those operating amplifiers.

The second main part is designing an active crossover filter which has capability of separating the

base signal from the treble. The crossover filter has ability to divide its output into main two

outputs which is base and treble even it receives full spectrum audio signal in to the input. The NI

Circuit Suits Multisim software used here for designing the filter and run the circuit. The bode

plotter is used here for show the output signal.

The last part is designing and implements a two stage BJT amplifier with a rated input and output

impedance. The total gain of two BJT assumed as thirty. Two BJT transistors are cascade in the

design. Using the circuit design calculated the components value and manipulated results. The NI

Circuit Suits Multisim software is used here for design and verifies the circuit.


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3. Introduction

Operating amplifiers have two inputs and one output. One input terminal is negative ( - ) and

other one is positive ( + ). There is additional supply input to made the output voltage into zero

when input voltage is zero. When it comes to practical application it wont become zero and

have an offset voltage.

Offset parameters of an operational amplifier

Offset parameter in an op-amp can happen as a natural built in fault. It could occur by input

current and input voltage forms in an operational amplifier. So these two factors (input and

output parameter faults) are making a different voltage. According to these cases in the op-amps

it is divided to two parts as mentioned below.

Offset due to current input current

Small amount of current flows in to the input of the operational amplifier due to current leakage

in the op-amp. So when a big input impedance or source with large output impedance is used,

the current that flowed due to leakage is after that start to create a big turbulence of voltage drop

within the op-amp. Because of the balance less between both non inverting and inverting

amplifier terminals it is start to produce small offset voltage.

A output of an op-amp depend on input voltage, input offset current input bias current and both

input and output factors. These factor can be represent by following equations

Output offset voltage due to input voltage is =+

Output offset voltage due to input offset current =


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Total output voltage due to (Vio and Iio) =+

. .

Following three practical operational amplifiers are selected to do the calculations

1. AD741H2. AD743KR3. AD746BQ

Active crossover filter

Mostly a crossover network is used in audio stage amplification and separator of base and treble.

Using an electronic crossover eliminates the problem that besets an audio designer; an electronic

crossover circuit separates and amplifies selected frequency ranges for each frequency band. The

mid and high range frequency that comes from the supply frequency are then subtracted from the

output of the filter to provide the bass. These types of crossover circuits are phase coherent

BJT Transistors

The first ever BJT was invented by William Shockley at Bell laborites new jersey in 1949. It is a

3 terminal electronic device constructed by doping semiconductor material and it is created out

of sensitive silicon or germanium. As the material only decides the Vbe where for silicon it is 0.7

and for geranium 0.3 Depending on the structure it could be understood weather semiconductor

layer is electrons or holes design. These type of semiconductors are used in designs as amplifiers

switching devices and Impedance matching devices

There are certain advantages in an BJT they are

1. Low cost design2. Operating voltage is low so it could be used in sensitive places3.

High efficiency


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BADURDEEN SHAKEAL 9

4

SOLUTION FOR PROBLEM ONE

OFFSET OF OP-AMP


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4.1 AD741H Op-Amp

This is low cost and high accuracy operational amplifier.

The Analog Devices AD741H is a high performance mono lithic operational amplifier. All the

devices feature full short circuit protection and internal compensation. The Analog DevicesAD741J, AD741K, AD741L, and AD741S are specially tested and selected versions of the

standard AD741H operational amplifier. Improved processing and additional electrical testing

guarantee the user precision performance at a very low cost. The AD741J, K and L substantially

increase overall accuracy over the standard AD741C by providing maximum limits on offset

voltage drift nd significantly reducing the errors due to offset voltage, bias current, offset current,

voltage gain, power supply rejection and common-mode rejection. For example, the AD741L

features maximum offset voltage drift of 5 mWC, offset voltage of 0.5 mV max, offset current of

5 nA max, bias current of 50 nA max and a CMRR of 90 dB min. The AD741S offers guaranteed

performance over the extended temperature

range of -550C to +1250C, with max offset voltage drift of 15 mV/C, max offset voltage of 4

mV, max offset current of 25 nA, and a minimum CMRR of 80 dB.

Connection Diagram

Characteristics Chart of the op-amp

Description Typical Maximum

Input offset voltage 1.0 mV 6.0 mV

Input offset current 20 nA 200 nA

Input bias current 80 nA 500 nA

Input impedance differential 0.3 M 2.0 M

Input voltage range 12 13

NC = No Connect

Mini-DIP (N) Package

NC = No Connect


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Take Rf= 192 and R1= 3.0


=+

1 1 0

= 0.064 V

= 64mV

When use this in application

When it come to the practical the offset voltage is little bit different then calculated voltage. But

this voltage is very close to manipulated result.


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4.2 AD707AR Operational Amplifier

This op-amp is a ultralow drift amplifier.

The AD707AR is a low cost, high precision op amp with state-of- the-art performance that

makes it ideal for a wide range of precision applications. The offset voltage spec of less than 15

pVis the best available in a bipolar op amp, and maximum input offsetcurrent is 1.0 nA. The top

grade is the first bipolar monolithic op amp to offer a maximum offset voltage drift of 0.1

mV/0C, and offset current drift and input bias current drift are both specified at 25 pA/ 0C

maximum.

The AD707's open-loop gain is 8 V/pV minimum over the full 10 V output range when

driving a 1 kW load. Maximum input voltage noise is 350 nV p-p (0.1 Hz to 10 Hz). CMRR and

PSRR are 130 dB and 120 dB minimum, respectively. The AD707 is available in versions

specified over commercial,

industrial and military temperature ranges. It is offered in 8-pin plastic mini-DIP, small outline

(SOIC), hermetic cerdip and hermetic TO-99 metal can packages. Chips, MIL-STD-883B, Rev.

C, and tape & reel parts are also available.

Circuit Diagram


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Input offset voltage 30 uV 90 uV

Input offset current 0.5 nA 2.0 nA

Input bias current 1.0 nA 2.5 nA

Input impedance differential 24 M 100 M

Input voltage range 15 30



=

+

3 0 1 0

= 1.92 mV


Specially in this particular operational amplifier the calculated output offset voltage and the

application output offset voltage are same. Therefore this model AD707AR op-amp is more

accurate and very close to ideal op-amp.


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4.3 AD743KR Op-Amp

This is a ultralow noise BiFET operational amplifier

The AD743KR is an ultralow noise precision, FET input, monolithic operational amplifier. It

offers a combination of the ultralow voltage noise generally associated with bipolar input op-amps and the very low input current of a FET-input device. Furthermore, the AD743 does not

exhibit an output phase reversal when the negative common-mode voltage limit is exceeded.

The AD743's guaranteed, maximum input voltage noise of 4.0 nV/VHz at 10 kHz is

unsurpassed for a FET-input monolithic op amp, as is the maximum 1.0 mV p-p, 0.1 Hz to 10

Hz noise. The AD743 also has excellent dc performance with 250 pA maximum input bias

current and 0.5 mV maximum offset voltage.

The AD743 is specifically designed for use as a preamp in capacitive sensors, such as ceramic

hydrophones. It is available in five performance grades. The AD743J and AD743K are rated

over the commercial temperature range of 00C to +700C. The AD743A and AD743B are rated

over the industrial temperature range of -400C to +850C. The AD743S is rated over the military

temperature range of -550C to +1250C and is available processed to MIL-STD-883B, Rev. C.

The AD743 is available in 8-pin plastic mini-DIP, 8-pin cerdip, 16-pin SOIC, or in chip form.

Connection diagram of AD743KR op-amp



Input offset voltage 0.1 mV 0.5 mV

Input offset current 40 pA 150 pA

Input bias current 150 pA 400 pA

Input impedance differential 1 1 0// 20 //pF 3 1 0// 18 //pF

Input voltage range 20 13.3


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=+

0.1 10

= 6.4 mV


When it comes to the practical the offset voltage is little bit different then calculated voltage. But

this voltage is very close to manipulated result.


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Reduce offset Voltage

4.4 Method 1

Setting offset voltage zero using potential meters.

To reduce the offset voltage of the op-amp one assumption make. That is connect potentiometer

for inverting input. In this test the same op-amp is taken to show output off set effect in previous

illustration. There for R1, and Rfvalues of the op amp keep unchanged and connect 10 k

potentiometer. The tested results of output offset voltage of the op-amp. Simulation result with

potentiometer. That shows output off set voltage effect can be reduced to more significant level

from this method. The below table shows results more clearly

Configuration Output offset voltage

AD741H op-amp without

potentiometer63.979 mv

AD741ch op amp with

potentiometer0 V


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4.5 Method 2

Connecting a series op-amp with final output

In this analysis can implement such a simple test to eliminate output offset voltage eliminated by

DC input offset voltage. A series 1uF series capacitor is added with output terminal of the op-

amp. Therefor this capacitor blocks all DC voltage and allows flowing only AC voltage through

the output terminal. There for can remove DC offset input automatically and utilize needed

application using op-amp. But this method can only remove DC input off set and ac voltage

from the input is keep remaining.

In the simulation result shows multi meter XMM1 is direct output from op-amp and it shows 6.4

mV output offset voltage. But the second multi meter is connected through 1uF capacitor and it

reads 17.829 nV. Therefore the output offset voltage is reduced and it became very close to zero.

Comparison of both states.

configuration Output offset voltage

Without connecting series capacitor 6.4 mv

With connecting series capacitor 17.829 nV


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4.6 Method 3

Reduce offset voltage using null pin configuration

In this test AD743KR op-amp is used here and its null pin configuration diagram is given in the

data sheet. This data sheet has provided also how is schematic diagram power the supply for this

op amp has provided bypassed with two capacitors for each supply and which is called

recommended power supply bypassing. The rated is 15V dual supply and internal power

dissipation of this op amp is 1.0W. The simulation result for overcome this offset effect is as

follows.

Pin no 1null decompensation

Pin no 4compensation

Pin no 5null compensation


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The output voltage shown here is very low and it is in femto value and very close to zero.

Comparisons of states.

configuration Output offset voltage

Without offset null pin 6.408 mv

With use of offset null pin 260.535 fV

The result here is for the same op-amp when the use the null pin the offset voltage is reduced

and it get close to zero. It is clearer effect of input offset voltage can be significantly reduced

from this configuration with potentiometer use. The percentage of potentiometer can adjust untilthe output voltage becomes zero. The different controls of the potentiometer make slightly

difference in the output.

Potentiometer resistance % Output offset voltage

0 % 260.535 fV

25% 260.535 fV

50% 260.535 fV

100% 260.535 fV

Here are the same values shown by output with adjustment of potentiometer.


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5

SOLUTION FOR PROBLEM TWO

ACTIVE CROSSOVER FILTER


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5.1 Design an active crossover filter.

The crossover filter is means split audio frequency range ( 20 -20k herts ) into two or three

bands. A active crossover filter to divided in to two bands is designed here. Those are bass and

treble. The slope of filter can make more accurately and cost is low compared to passive filters

is an advantage of active crossover filters. The design of active crossover is simpler than passive

filters then and it can be modified easily. This filters are made with only passive elements such

as resistors, capacitors and inductors and it is called passive filters. Also a filter network

includes transistors and operational amplifiers are called active filters.

Mostly a crossover network is used in audio stage amplification and separator of base and treble.

Using an electronic crossover eliminates the problem that besets an audio designer; an electronic

crossover circuit separates and amplifies selected frequency ranges for each frequency band. Themid and high range frequency that comes from the supply frequency are then subtracted from

the output of the filter to provide the bass. These types of crossover circuits are phase coherent

Schematic diagram of the active crossover filter


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This is a audio signal frequency ranges and it was divided into three different filtering ranges.

Crossover filters frequency range according to above three basic bands.

Here designed Cut off frequency for bass range is 300 Hz. And designed low pass filter.

Designed Cut off frequency for treble range is 3.0 KHz and use high pass filter.

Therefor according to this frequency can assume filters value like resistance and capacitors of

the filters.

Ausdio Signals

(20Hz-20kHz)

Base band(20Hz-200Hz)

Midrange

(200Hz-2kHz)

Treble

(2Khz-20kHz)

Bass 20 Hz200 Hz 20 Hz140 Hz

Treble 2 KHz20 KHz 2.5 KHz20 KHz


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5.2 Calculations

=

Fc = cutoff frequency, R = Resistance and C = Capacitor

= 1

Bandwidth (BW) = Fc2Fc1

Bass frequency would be considered as low frequency in the ongoing calculations

Low frequency bellow 300 Hz is base tone

Fc = 300 Hz, R1 = 10k

300 =

=

= 53nF

So, Fc = 300 Hz, R1 = 10k, = 53

Treble frequency would be considered as High frequency in the ongoing calculations

High frequency above 3000 Hz is treble tone

Fc = 3.0 kHz, R1 = 10k

3 1 0 =

=

= 530nF

So, Fc = 300 Hz, R1 = 10k, = 530

Bandwidth = Lower cutoff frequencyupper cutoff frequency

BW=3.0 kHz - 300Hz


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BW= 2.7 KHz

Values of Q factor is given

Q factor Equation

=

For Low Pass Filter

=

=

=

.

= 0.111

For high Pass Filter

=

=

=.

.

= 1.111

For Low Pass Filter = 0.111

For high Pass Filter = 1.111


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5.3 Multisim Simulation Diagrams

Low Pass cutoff

High pass cutoff


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6

SOLUTION FOR PROBLEM THREE

BJT TRANSISTER


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BJT Transistor

Schematic diagram of the circuit


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Design Implementation and Calculations

Values to carry on equation and construction of circuit

Low cutoff frequency 100Hz

High cutoff frequency 20KHz

Input impedance 1K

Output impedance 100

VCC 12V

Fundamental block diagram

Vin

Vout

Vin

Zin=1K

Zout=100

AV1AV2


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Total gain

=

20 = 10 2

Therefore = 10, = 2

= 0.7

Ic = Ie

=

Calculation stage 0ne, low frequency part (common emitter voltage divider)

To maintain stability of circuit assumption is made

Calculate VE

=.

=.

= 1.2

Calculate Re

=

=.

= 600

Datasheet values are given below

Vce =5V

Ve =1.2V


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Therefore calculate Vc

Vc =Ve + Vce

= 1.2 + 5

= 6.2V

Calculate Rc

=

=.

= 2900

= 2.9

Calculate re

=

=

= 13

Calculate RL

Av1= ( Rc // RL ) /re

10 = ( Rc // RL ) /re

10 13 = Rc// RL

RL= 136.1

Calculate RB

Zin= Rb// hie


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hie Value to be take from datasheet

Zin= Rb// hie

Rb= (hie*Zin) // (hie-Zin)

= (5.5K *1K ) // (5.5K - 1K )

=1.22K

Calculations can be carried out to find the value of Vb because Vbe of silicon transistor is 0.7

Vb = Vbe + Ve

=0.7 V + 1.2 V

=1.9V

Apply voltage dividing rule to find R1

Vb= Vcc*R2 / R1+R2

=12*R2) / ( R1+R2)

R1=5.31*R2

Value of R1 and R2 taking value from and

Rb=R1//R2

1.22K= (5.31*R2)*R2//(5.31*R2)+R2

R2=1.58K

Rb=R1//R2

R1=Rb*R2 / Rb-R2

1

2

1 2


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=1.22 K*1.58K//1.22 K - 1.58K

R1=5.35 K

Find the value of C

Capacitor has to be able to bypass the low cutoff frequency which is assigned as 100Hz

C =1 / (2*F*re)

=1/ (2*100*13)

=122F

The circuits bypass capacitor has been calculated which is a vital part of the circuit now the

calculation has to be carried on to find Cin, but there is another way which insists that the value

of the capacitor Cin only has to be much lesser than C so we

So Cin=20 F (this is an assumption value only)

A filter capacitor has to be used in parallel with RL to meet the upper cutoff frequency in the

design which is 20KHz

Calculate Thevenin resistance to get Cf

R1= Rc//RL

=2.9K // 136.1

=129.99

Cf=1 / (2*F*re)

=1/ (2*20*103*129.99)

=61.2nF


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Calculation stage two high frequency part (emitter follower configuration)

Zout

Zin=136K

Calculate re

Zout = re

Zout=100

re=26mV/Ie

100 =26mV / Ie

Ie =26mV /100

=0.26 mA

Data imported from datasheet

Vce 5V

Ve 5V

hfe 370

AV2

Emitter follower

configuration


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Re= Ve / Ie

= 5V/0.26 mA

=19.2 K

Calculate Rb

Zin= Rb//hfe*Re

136.1= Rb//370*19.2K

Rb=(370*19.2 K )* 136.1 //(370*19.2 K ) -136.1

=136.1

Calculate Vb

Vb=Vbe + Ve

=0.7 V + 5 V

=5.7V

Apply voltage dividing rule to find R1

Vb= Vcc*R2 / R1+R2

5.7=12*R2) / ( R1+R2)

R1=1.105*R2

Value of R1 and R2 taking value from and

Rb=R1//R2

136= (1.105*R2)*R2// (1.105*R2)+R2

R2= 259.07

3

2 1


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Rb=R1//R2

R1=Rb*R2 / Rb-R2

=136 *1.11K//136 - 1.11K

R1= 286.288

Total circuit component chart

List of components Value received by

calculation

E24 standard resistor and capacitor

values

Re 600 620Rc 2.9K 3K

re 13 13

RL 136.1 130

Rb 1.22K 1.2K

R2 1.58K 1.5K

R1 5.35K 5.6K

C 122F 120 FCin 20F 20 F

CF 61.2nF 62 nF

Re 19.2K 20K

Rb 136.1 130

R2 259.07 270

R1 286.288 300


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Multisim simulations

At lower cuttoff frequency 100Hz

At upper cuttoff frequency 20KHz


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At mid band 2.5 kHz


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Discussion and conclutions

Studying operational amplifiers is a part of the course work we studied about op amp

characteristics and there implantation in circuits, here a critical part that we studied was that it

was offset voltages and how to null it the using a potentio meter

In the crossover filter after going through the circuit design it is possible for a person to

understand its complexity. Not only in the calculation part, but also in the circuitry part as well.

All parts like the high pass, low pass and band pass filters are tested for stability and it is

working at its full optimum levels. The crossover designed here is a limited to an audio system.

The increase of complexity in the circuit is because of the integration of active filters this design

could be more simplified using passive components. Therefore the design has gone from simple

to complex; but if passive components are used the circuit would have more distortion involved.

If the simplicity is increased the processing time is also reduced therefore increasing high

amounts of crossover distortion and reducing overall quality of the system

The circuit has been tested and stimulated and problem has not been raised during the process.

The use of multisim in circuit has a great effect on the circuit. If multisim wasnt present the

designer would have to create the circuit in a real bread board to get his desired value, use of

software has saved time money and overall possible mistakes. The above circuit could be more

simplified. By the means of the removal of the mid-range part

In the BJT part the circuit has been tested and stimulated, No problem has been raised during the

process. The use of multisim in circuit has a great effect on the circuit. Here in this simulation a

board plotter is used where it clearly shows the bandwidth of the circuit. In this circuit

temperature factor isnt considered this might be a problem in places where a voltage bias cct is

used because a divider is a practical value region if load across Rc isnt handle properly this

may lead to temperature rise within the bjt therefore reducing gain parameters eventually

overheat might destroy the BJT itself


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Reference

1. Electronic Devices and circuit theory [2006], 10th edition. United Kingdom.

2. Parallel resister calculator [20th may 2012] http://www.sengpielaudio.com/calculator-paralresist.htm

3. LED resister calculator [20th may 2012]http://www.ohmslawcalculator.com/e24_resistor_sizes.php (assessed of 2nd may 2012)

4. Analogue electronics BJT [24th may 2012]http://en.wikibooks.org/wiki/Analogue_Electronics/BJTs (assessed of 2nd may 2012)

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A203SE Analog Electronics Coursework

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