matching network
TRANSCRIPT
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University Mhamed Bougara ,Boumerdes
Institute of Electrical and Electronic Engineering
Department of Electronics
Done by
-Oussama Gassab -hammouya houssam - Achraf Djerida
Groupe 01
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n communication we have to perform some conditions on
the signals in order to transmit or receive them , like
modulating , demodulating and filtering , to do that we have
to build required circuits with specified precision and conditions
.
n order to build the needed circuits for the needed
communication application we have to do the theoretical
analysis by doing the mathematical calculations which
applies the physical formulation of the devices , and that
analysis simulated by using a software , if the results in the
simulator are matches the mathematical analysis , than the
circuit can be built in the real world in order to perform its
required job.
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-Single transistor ampli f iers
Objectives :
1- to learn how to bias and test a transistor amplifiers
We have the following circuit :
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The mathematical analysis :
= = 10 51 = 5And when we take = 50+300
2= 175 we have
= 5.7 . 103
so
=
=
100.655.7 .103
=
1.64Multisim simulation :
We got the following results
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Measuring the gain voltage = ( ) ( ) = 1921 = 192
When change the transistor BJT-NPN-VIRTUAL we got
When we change the transistor the beta is changed and all
the Q points it has been changed , in that circuit the changing on
beta will correspond high change to collector current . so in this
case the transistor base current is unstable relative to the
changing of beta , in addition the beta factor is sensitive to
temperature and even to the current inside the transistor , that is
mean the collector current is unstable at all . so this bias is not
practical because it is not stable .
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Part 02 :
The mathematical analysis
= 1 = 11 = 1 = =104.51
1= 4.5
1 = 39 2 = 8.2
The gain is A= 174
When change the transistor to BJT_NPN_VIRTUAL
We have got the following result
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So the gain is = 119.7070.999594 = 119.8We see that the gain is approximetly for the first one and the Q
points are nearly the same so this bias stabilize the Q points and
it is applicable . so the emitter resistor stabilize the Q point for
the changing of beta
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Part 03 :
We have the following circuit :
The mathematical analysis
We have computed by using the fact that1 = = = 1 = 100651 = 9.35And for maximum symmetrical swing = 2
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= = 2 = 102 1 = 5 By using the oscilloscope we have got the following
So the gain = 214,038 1.375 = 155.66When increase the voltage to 20 mv we have the following
Result .
Explaining this distortion .
We know that the transistor is saturated when Vce is less than We have = ()
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And since
>
|
| 100 = 105 > 100 All the conditions of the approximation are satisfied so we
expect a results that matches the thoery models .
When we perform the ac analysis we got
So at resonance frequencies the impedance is 17.1075 k
which matches the theory 20k
And the bandwidth is about 8.6445 which and the theory
band width is 5kHz
When we build the equivalent RLC circuit as follow
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The ac analysis for this circuit is
So the results matches the equivalent circuit the bandwidth
is 7.5131 kHz as shown above
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t is very easy to perform the theoretical analysis in
papers by using only the mathematical formulas , and
that what we have accustomed to do . about us we
have an experiment to deal only with papers , pan , and
calculators to solve a problem , and we thought that the
problem it has been solved , but in reality we found thatwe have solved only mathematical formulas , and to
simulate that in the simulator there are many concepts
must realized and many ideas must performed .
hat is mean to put a such application in real world
we have to recognize many things that correspond
with losses and errors and approximations. Wehave learnt that the engineer must have experience in the
field with real appliances not only the theoretical formulas
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