1. Basic
Method
Diode is a
semiconductor device connection P - N simplest possessing a current in one
direction only. Thinning and thickening of the depletion layer of the junction
between the key properties of the diode connection of P - N. In contrast to a
resistor, a diode does not behave linearly on the applied voltage diodes
instead produces the characteristic I - V is exponential.
Notation or symbol
diode connection P - N is shown in the following figure.
Figure 1 symbol diode
connection P-N
There are
two operating regions diode connection P - N and there are three conditions
that bias can be given:
a.
Zero Bias - a condition in
which there is no external potential is given to both ends of the diode
produces a balance amount of majority carriers, electrons and holes, and both
are moving in the opposite direction. This equilibrium condition is known as
dynamic equilibrium (dynamic - equilibrium).
b.
Reverse Bias - a condition in
which the positive pole is connected to an external source of potential N side
of the diode and the negative pole is connected to the external potential source
P side of the diode.
Figure 2 Reverse Biad in Diode
This
condition results in a high resistance value between the junction and
practically does not produce the majority carrier flow with increasing
potential sources. However, a very small leakage current will pass through the
junction which can be measured in order microampere (mA).
c.
Forward Bias - The condition in
which the positive pole is connected to an external source of potential P side
of the diode and the negative pole is connected to the external source potential
N side of the diode.
Figure 3 Forward Bias on Dode
This
condition results in a junction resistance value P - N is so low that allow
very large currents flowing though only by a relatively small potential source.
Actual potential differences arising on both ends of the diode junction will
remain valuable due to the action of the depletion layer which is worth about
0.3 V to 0.7 V for germanium and silicon.
Zener
diode
It has been discussed
earlier that the current in the diode withstand reverse bias conditions and
will result in damage (breakdown) when a reverse voltage is given too large.
Unlike the case with so-called zener diodes or diode breakdown, basically the
same as the diode connection P - N standard unless specifically designed or
produced reverse breakdown voltage is lower and relatively constant so it is
best used in the reverse direction as the bias voltage regulator. The point at
which the zener diode breakdown voltage zener or conduction called “VZ”.
2.
Identificationof
Variables
Activity
1st:
a.
Manipulation
variables: Voltage diode (VD) (volt)
b.
Response
variables: Current diode (ID) (mA)
c.
Control
variables: Source Resistance (RS) (Ω) and Voltage source (VS) (volt)
Activity 2nd:
a.
Manipulation
variables: Voltage diode (VD) (volt)
b.
Response
variables: Current diode (ID) (µA for rectifier diode and mA for zener diode)
c.
Control
variables: Source Resistance
(RS) (Ω)
and Voltage source (VS) (volt)
3.
OperationalDefinition of Variables
a.
Voltage
source (VS) is voltage from power supply in unit volt.
b.
Resistor
source (RS) is the value of resistor which was used to resist the
current in unit ohm (Ω).
c.
Voltage
diode (VD) is applied voltage in diode in unit volt.
d.
Current
diode (ID) is the value of current which flow which measured by using
ammeter in unit mA in forward bias for rectifier diode and zener diode, while
in reverse bias was used mA for zener diode and µA for rectifier diode.
4.
Tools and Materials
a.
Power
Supply 20 Vdc, 1 piece
b.
Voltmeter
0-10 Vdc, 1 piece
c.
Ammeter
0-1 Adc, 1 piece
d.
Potentiometer,
1 piece
e.
Resistor, 1000Ω, 1 piece
f.
Rectifier
Diode, 1 piece
g.
Zener
diode, 1 piece
h.
Connection
cable.
5.
Work Procedure
Forward Bias
Conditions
a.
|
ID
|
|
VD
|
|
VS
|
|
VR
|
|
RS
|
|
D
|
|
+
|
|
_
|
b.
Measure
the source voltage of 2 V for the forward bias condition.
c.
Adjust
the minimum position potentiometer VR and observe the appointment of
the second measure on ammeter.
d.
Increased the bias voltage by adjusted the potentiometer
until the voltmeter showed the value of 0.05 V (or depending on the sensitivity
of the measuring instrument), wrote
the appointment of the ammeter on
the observation table as ID
e.
Applied
activities (c) for each increment of 0.05 V bias voltage up to the maximum.
Reverse Bias Conditions
a.
Measured the source voltage of
10 V for rectifier diode and 15 V for zener diode.
b.
Increased the bias voltage by adjusted the potentiometer
until the voltmeter showed the value of 0.5 V (or depending on the sensitivity
of the measuring instrument), wrote
the appointment in ammeter on the observation table as ID.
c.
Perform
activities (b) for each increase in bias voltage up to 0.5 V maximum.
d.
Record
all your observations carefully in the observation table.
6.
Data/ Data Analysis
a.
Observation
table
Activity 1(ForwardBias)
1)
For
Rectifier Diode
Known:
Table
1.1 Relationship between voltage diode (VD) and current diode (ID)
|
No.
|
VD (volt)
|
ID(mA)
|
|
1
|
0,05
|
0,00
|
|
2
|
0,10
|
0,00
|
|
3
|
0,15
|
0,00
|
|
4
|
0,20
|
0,00
|
|
5
|
0,25
|
0,00
|
|
6
|
0,30
|
0,03
|
|
7
|
0,35
|
0,10
|
|
8
|
0,40
|
0,24
|
|
9
|
0,45
|
0,77
|
2)
For
Zener Diode
Table 1.2 Relationship
between voltage diode (VD) and current diode (ID)
|
No.
|
VD
(volt)
|
ID(mA)
|
|
1
|
0,05
|
0,00
|
|
2
|
0,10
|
0,00
|
|
3
|
0,15
|
0,00
|
|
4
|
0,20
|
0,00
|
|
5
|
0,25
|
0,00
|
|
6
|
0,30
|
0,00
|
|
7
|
0,35
|
0,00
|
|
8
|
0,40
|
0,00
|
|
9
|
0,45
|
0,03
|
|
10
|
0,50
|
0,07
|
|
11
|
0,55
|
0,21
|
|
12
|
0,60
|
0,88
|
Activity
2(Reserve Bias)
1)
Rectifier
Diode
Known:
Table
2.1 Relationship between voltage diode (VD) and current diode (ID)
|
No.
|
VD
(volt)
|
ID(µA)
|
|
1
|
0,5
|
0,00
|
|
2
|
1,0
|
0,00
|
|
3
|
1,5
|
0,10
|
|
4
|
2,0
|
0,10
|
|
5
|
2,5
|
0,20
|
|
6
|
3,0
|
0,20
|
|
7
|
3,5
|
0,30
|
|
8
|
4,0
|
0,30
|
|
9
|
4,5
|
0,40
|
|
10
|
5,0
|
0,40
|
|
11
|
5,5
|
0,50
|
|
12
|
6,0
|
0,50
|
|
13
|
6,5
|
0,60
|
|
14
|
7,0
|
0,60
|
|
15
|
7,5
|
0,70
|
|
16
|
8,0
|
0,70
|
|
17
|
8,5
|
0,80
|
|
18
|
9,0
|
0,80
|
|
19
|
9,5
|
0,90
|
2)
For
ZenerDiode
Known:
Table 2.2
Relationship between voltage diode (VD) and current diode (ID)
|
No.
|
VD
(volt)
|
ID(mA)
|
|
1
|
0,5
|
0,00
|
|
2
|
1,0
|
0,00
|
|
3
|
1,5
|
0,00
|
|
4
|
2,0
|
0,00
|
|
5
|
2,5
|
0,01
|
|
6
|
3,0
|
0,05
|
|
7
|
3,5
|
0,22
|
|
8
|
4,0
|
0,63
|
|
9
|
4,5
|
2,25
|
b.
Graph
method
Ø For
Rectifier Diode
Forward
Bias
|
Imax = 0,77 mA
|
|
VDD = VS
|
|
|
Graph
1.1 Relationship between Diode
Current (ID) and Diode Voltage (VD)
Reserve
Bias
|
VDD =VS
|
|
Imax
= 0,9 mA
|
|
VD
|
Graph
1.2 Relationship between Diode
Current (ID) and Diode Voltage (VD)
So, the mix graph in
Rectifier Diode
Graph 1.3 Combination of Forward Bias and Reverse Bias on
Rectifier Diode
Ø Zener
Diodev vb v vb v
Forward
Bias
|
Imax
= 0,88 mA
|
Graph
1.4 Relationship between Diode
Current (ID) and Diode Voltage (VD)
|
VD
|
|
VDD = VS
|
Reserve
Bias
|
VDD = VS
|
|
ID
|
|
VD
|
|
Imax
= 2,25 mA
|
Graph
1.5Relationship between Diode
Current (ID) and Diode Voltage (VD)
|
|
So,
the mix graph in Zener Diode
Graph 1.3 Combination of Forward Bias and Reverse Bias on
Rectifier Diode
7.
Discussion
Based on
data analysis, it can be seen that the current of diode was constant for few
times. It still constant at zero point of diode current axis. Until reach a
certain point in diode voltage, the curve will increase directly. For forward
bias, the positive pole of the source was connected to the type-p of diode. The
curve was up to the maximum current of diode. To find the load line, it can be
taken by drawing straight line from the maximum current of diode to the source
voltage which is used. Then, from the intersection of the load line and curve
of current-voltage, it can be determined as the working point of diode. It was
obtained in forward bias on rectifier diode and zener diode.
Differ from forward bias, reverse bias was the invert of it.
For reverse bias, the positive pole of the source was connected to the type-n
of diode. The curve is differ from the curve of relation between diode current
and diode voltage in forward bias. The direction of the curve is going to the
negative value as we can see from the curve on table analysis. To determine the
load line and working point of the curve are not different from the way to
determine them on the curve of relation between current and voltage on forward
bias.
8. Conclusion
According to this experiment we can conclude that:
a.
The curve of characteristic diode is the relationship
between the diode current and diode voltage for rectifer diode and zener diode,
where the forward bias condition, when diode was
given
, the first
current of
.
b.
Load line is determined by drawing a straight line from
to
. then determine the working point or the point of
intersection betweenthe load line and the characteristic curved diode.
c.
The determination of the value of the zener voltage diode
characteristic curve based on the view point of intersection between the load
line or curved diode characteristic stating current and voltage diode.
9. Bibliography
Tim
Elektronika Dasar. 2013. Penuntun Praktikum dasar I. Makassar. Unit
Laboratorium Elektronika dan Instrumen UNM
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