# Question 2 ```ECE Department
Electronics Lab
ECE371
Student ID
‫محمد محمود احمد عبد المتعال‬
‫محمد مرسي عبد العظيم مرسي‬
‫محمد مصطفى حسين الغوري‬
‫محمد وائل جمال عيسى عايش‬
33563/33564/33565/33566
Experiment #
E10
Experiment Name
Introduction to PLLs
Student Name
Date Attended
Shift
2
Accuracy:
Neatness:
Results analysis:
Simulations and
measurements performed
accurately and fully. Lab
testing procedures followed.
Graphs and tables presented
in a neat and readable shape.
Graphs are interpretable and
units of each quantity are
clearly written. Axes are
clearly labeled (quantity and
unit)
Results discussed and
Comparison between
measured and simulated
results is outlined.
In case of falsified or copied
results, the grade is set to
ZERO while informing the lab
supervisor to take a
disciplinary action
10
10
10
1
30
EXPERIMENT E-X
Phase Locked Loop
Question 1:
Write down a summary of PLL experiment theory in the area below:
(Don’t copy and paste from the internet or the experiments notes itself)
PLL theory
PLL is a system that generates a signal that has a frequency
equal to the i/p one ;
when the phase difference between the i/p &amp; o/p signals is
const then they have the same freq, as -phase = integration
freq - in other words simply the PLL generates an o/p signal
whose phase tracks the i/p '' PASHE LOCKED LOOP ''
It`s a negative feedback system much similar to the
''buffer'' circuit , the circuit consists of three main blocks
phase detector, LPF and VCO .
*The PD can be implemented simply using XOR gate as
when the i/p signal &amp; the feedback are not the same then the
output is 1 &amp; equals zero if the two inputs are the same.
When the phase difference between the inputs increases, the
width of the output pulses increases linearly then the average
value of the output increases linearly.
*The output is then passed through a LPF to take the
required average value. As it only passes the DC component
which is the required average value and filters the other
harmonics.
*The VCO: It generates an output signal whose
2
frequency is proportional to the input voltage, and continues
the loop.
Question 2:
Insert the required plots in the specified spaces:
b) VCO response (Output frequency VS Vctrl)
c) The PLL output signal when Vctrl = 1 V (VS time)
3
4
Question 3:
Insert the required plots in the specified spaces:
b) Inputs of the phase-frequency detector at input frequency = 1 KHz
c) Minimum and Maximum Frequencies
Fmin = ………500 Hz……, corresponding control voltage = …0.54V……….
Fmax= ……4 KHz…... corresponding control voltage = …4.7V………..
5
Minimum Frequency Graph
Maximum Frequency Graph
6
Question 4 (Bonus):
Insert the required plots in the specified spaces:
a) PLL Orcad schematics (with divider)
b) Inputs of the phase-frequency detector at input frequency = 1 KHz
7
c) Input and Output of the PLL (on the same graph)
d) Minimum and Maximum Frequencies (input)
Fmin = …………… , corresponding control voltage = ………….
Fmax= …………….., corresponding control voltage = …………..
8
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