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Name:
Matric No:
Section:
INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
MID TERM EXAMINATION
SEMESTER I, 2014/2015 SESSION
KULLIYYAH OF ENGINEERING
Program
Time
Duration
Section(s)
Course Title
: ENGINEERING
: 11.00 am – 13.00 pm
: 2 hours
: 1-9
: Electronics
Level of Study
Date
Course Code
: UG1
: 4/11/2014
: ECE 1312
This Question Paper Consists of Eight (8) Printed Pages Including Cover Page With Five (5)
Questions.
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INSTRUCTION(S) TO CANDIDATES
DO NOT OPEN UNTIL YOU ARE ASKED TO DO SO
Total mark of this examination is 50.
This examination is worth 25% of the total assessment
Answer all 5 (Five) questions.
Any form of cheating or attempt to cheat is a serious offence which may lead to
dismissal.
Question 1
a) What are active and passive devices? Give an example for each of them.
(4 marks)
b) Fig. 1(b) shows a voltage amplifier circuit. The amplifier input resistance, output
resistance and open circuit voltage gains are 𝑅𝑖 = 2.5 kΩ, 𝑅0 = 200 Ω and 𝐴0 =150
respectively. A voltage source with resistances 𝑅𝑆 = 1.5 kΩ and a load resistance of
𝑅𝐿 = 500Ω are connected to the amplifier as shown in Fig. 1(b).
(6 marks)
i. Find the value of vi in terms of vs
ii. Find the value of vo in terms of vs
iii. Deduce the value of the actual voltage gain, 𝐴𝑣 =
Fig. 1(b)
𝑣𝑜
𝑣𝑠
of the amplifier
Question 2
a) How to make a p-type and a n-type extrinsic semiconductors?
( 4 marks)
b) At 30o C temperature with thermal equilibrium condition, the minority charge carrier
(electron) concentration of a p-type silicon material is 2.5×105 cm-3. Determine the
acceptor atom concentration of the material. (Boltzmann’s constant 𝑘 = 86 ×
10−6 𝑒𝑉/𝐾). (Please refer to the table on the last page)
( 6 marks)
Question 3.
As shown in Fig. 3, a Silicon pn-junction diode is working at a temperature 350° K. The diode
has been constructed with doped at 1.2 × 1016 cm-3 in p-type and 1.0 × 1017 cm-3 in n-type
semiconductors. Determine the diode current 𝐼𝐷 in the circuit by using the diode constant voltage
model where V equals to the built-in potential voltage of the diode, Vbi
(Please refer to the table on the last page)
(10 Marks)
Fig. 3
Question 4.
a) State two differences between the center-tapping full- wave rectifier and bridge rectifier
circuits.
( 4 marks)
b) Design a full-wave bridge rectifier circuit for a desired peak output current, 𝐼𝐿 = 150 mA
with a transformer feed as shown in Fig. 4(b). Assume that the transformer primary is
connected with a 220 V(rms) main supply line and the circuit diode cut-in voltage Vγ =
0.65 V. (Hints, determine the transformer turns ratio).
( 6 marks)
Fig. 4(b)
Question 5
a) Design a Zener diode voltage regulator circuit as shown in Fig. 5(a). Consider the Zener
breakdown voltage and current are, 𝑉𝑍 = 8.5 𝑉 and 𝐼𝑍 = 35 𝑚𝐴 respectively.
( 6 marks)
Fig. 5(a)
b) A diode clipper circuit as shown in Fig. 5(b). Its input voltage 𝑣𝐼 is a 20 VPP triangular
waveform. Sketch the output waveform 𝑣𝑂 of the clipper circuit on the graph is given at
the right side of the circuit. Assume that 𝑉𝐵 = 3 𝑉 and 𝑉𝛾 = 0.65 𝑉.
( 4 marks)
Fig. 5(b)
Semiconductor Constants
Material
Bandgap Energy (eV)
B (cm-3 K-3/2)
Silicon
1.1
5.23 × 1015
Germanium
0.66
1.66 × 1015
Gallium Arsenide
1.4
2.10 × 1014