V-I characteristics of Zener Diode

Basic Electronics Lab Course

1. COURSE: Basic Electronics Lab Course
CODE : CSE 213
Experiment Name:
“ V-I characteristics of Zener Diode”.
Experiment no: 03
Date of experiment: 31/07/2020

NAME: MOHAMMAD NURUL ISLAM EMON
DEPARTMENT: COMPUTER SCIENCE AND ENGINEERING



1. Objective: To plot the VI characteristics of a Zener diode.
2. Theory
Zener diode is a P-N junction diode specially designed to operate in the reverse biased
mode. It is acting as normal diode while forward biasing. It has a particular voltage
known as break down voltage, at which the diode break downs while reverse biased. In
the case of normal diodes the diode damages at the break down voltage. But Zener
diode is specially designed to operate in the reverse breakdown region. Zener
breakdown: When a diode is heavily doped, it’s depletion region will be narrow. When a
high reverse voltage is applied across the junction, there will be very strong electric field

2. at the junction. The electron hole pair generation takes place and heavy current flows.
Breakdown: There is a limit for the reverse voltage can increase until the diode
breakdown voltage reaches. This point is called Avalanche Breakdown region. At this
stage maximum current will flow through the zener diode. This breakdown point is
referred as “Zener voltage”.
3. Equipment
A. A zener diode
B. A DC voltage supplier
C. Bread board
D. 100Ω resistor
E. Connecting wires
3. Circuit Diagram

Figure: V-I characteristics of Zener Diode
5. Data Collection:
Table for forward-bias voltage and forward current:
Forward bias Voltage (V) Forward Current If(mA)
0.0 0
0.2 0.001
0.3 0.002

3. 0.6 0.5
0.7 1.1
0.8 2.2
1.0 3
1.2 5.1
1.4 7.5
1.6 10
1.8 15
2.0 20.4
2.2 25.3
2.4 30

Table for reverse-bias voltage and reverse current:
Reverse bias Voltage(v) Reverse current (A)
0 0
0.5 1.1
7.1 2.33
9.1 3
11.1 4
13.1 5.5
15.1 7
17.1 9.2
19.1 11
21.1 13.7
23.1 15
25.0 25





Graph
Graph (Instructions):

4. 1. Take a graph sheet and divide it into 4 equal parts. Mark origin at center of the graph sheet.
2. Now mark + ve x-axis as Vf - Ve x-axis as Vr + Ve y-axis as If - ve y-axis as Ir

5. .
7. Discussion
 The illustration above shows this phenomenon in a current vs voltage
graph with a zener diode connected in the forward direction .It behaves
exactly as a standard diode.


In the reverse direction however there is a very small leakage c
urrent between 0v and the zener voltage –i.e. just a tiny amount of
current is able to flow.
.