EE Lab: Diode IV Characteristics
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Ahmed Razi UllahEE Lab: Diode IV Characteristics
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Ahmed Razi UllahDepartment of Electrical Engineering
Faculty Member: _______________ Dated: ________________
Semester: _____________ Section: ________________
EE215: ELECTRONIC DEVICES AND CIRCUITS
Lab 03: IV Characteristics of pn-junctions
PLO4/CLO4 PLO5/CLO5 PLO8/CLO6 PLO9/CLO7
Name Reg. No Viva /Quiz / Analysis Modern Ethics and Individual
Lab of data in Tool Usage Safety and
Performanc Lab Teamwork
e Report 5 marks 5 marks
5 marks
5 marks 5 marks
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Lab 03: IV Characteristics of pn-junctions
Objective: To Study the Characteristics & Applications of Diodes
1. The primary purpose of this lab is to develop a working knowledge of diode. Diodes can
be used in variety of circuits for various applications such as rectifiers, clippers/clampers
and voltage regulators.
EQUIPMENT REQUIRED
2. The following components and test equipment is required.
PN Diode (D1N4002 or any other diode of the same family)
Oscilloscope
Function Generator
Resistors (1k)
Capacitors
Power Supply
The Experiment:
3. The experiment is broken down into two exercises. Each exercise has further been
divided into parts. Part I involves the simulation of the circuit on PSpice using Orcad-
Capture module. The second part involves the practical setup of this circuit and making
required measurements, tabulation and its analysis.
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Exercise – I (Part A) [Simulation]
4. The first part of the experiment is to draw a graph of the I-V relationship of a diode using
PSpice; this may be .accomplish by using the DC sweep analysis mode of the
simulation.
Figure-1A_1
Draw the circuit shown in figure 1A_1 on OrCad capture. Please make sure you have
saved the file.
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Since we are analyzing a diode, we would need to draw its I-V characteristic curve. To
do that, we need to simulate our circuit using DC Sweep profile settings.
Change the profile setting as shown in figure 1A_3. Please make sure that you know
what do we mean by DC Sweep and how various value changes would affect the graph
obtained.
You should make sure that the name of the voltage source is V1. If there is a different
name then you should change it accordingly.
Place the current marker/probe at the anode(upper pin) of the diode and run the
simulation.
Observe the plot.
Now Change the Values of DC Sweep and enter 0.1 for Start Value.
Repeat the experiment by selecting logrithmic scale. This can be done by simply
selecting the options shown in the given figure 1A_2.
Note: Only change the scale on the X-Axis to log this can be done by pressing the
button with Vertical lines as shown in figure 1A_2.
Use these
to convert
into log
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(Figure 1A_2)
(Figure 1A_3)
Save both graphs and sketch them with explanation. Also, answer the following
questions:
o How can you explain the behavior of the diode by looking at the logarithmic
curve?
o What differences do you observe in the logarithmic curve and linear curve?
Which scale would help you understand the diode behavior better?
Diode resistance is an important parameter of the diode. To observe the change in RD
with reference to increasing voltage, you need to follow the following steps:
o Simulate the circuit given in figure 1A_1 using linear scale DC sweep simulation
profile.
Start Value:0
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End Value:5
Increment:0.2
o After simulation, add trace as shown in the given figure 1A_4:
o Change the X-Axis to VD or V(D1:1)
o Observe the graph obtained
Figure 1A_4
The graph that you had seen so far was between Vin and ID. Now change the x-axis variable
by following the steps as shown in figure 1A_5, figure 1A_6 and figure 1A_7. This would be
ID vs VD curve of the diode. How can you explain the behavior of the diode from this curve?
(Figure 1A_5) – Go to axis settings
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(Figure 1A_6) – Here select the option “Axis Variable”
(Figure 1A_7) – Add V(D1:1) as your x-axis variable
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Answer the following questions
o Spot the threshhold/cut-in voltage of the diode from the I-V characteristic
graph? Do you think it is a silicon based diode or germanium based diode?
Explain your answer.
o Explain the behaviour of RD with respect to VD as observed in the graph drawn.
Exercise – I (Part B) [Implementation]
(Figure 1B_1)
5. This part of the experiment helps the students to set a simple diode circuit and take
measurements for drawing the I-V curves.
Procedure
On a breadboard, setup the circuit given as shown in figure 1B_1.
Apply the input voltage gradually increasing it from 0V and onwards, in steps of 0.2 volts.
Measure and tabulate the values of ID and VD until VD becomes almost constant
Observations/Measurements:
Plot ID vs VD forward characteristics using both linear scale and logarithmic scale. Please
make sure that you use MS Word/excel features for both linear scale and logarithmic
scale plot and include the plot in your lab report. Please follow the lab report format
provided by the instructor.
Determine the threshold voltage of the diode and explain if it is Silicon or Germanium
based diode.
Calculate the values of RD at different input voltages. Plot the graph and explain.
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