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Name:
Matric No:
Section:
INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA
MID TERM EXAMINATION
SEMESTER II, 2013/2014 SESSION
KULLIYYAH OF ENGINEERING
Program
Time
Duration
Section(s)
Course Title
: ENGINEERING
: 10.00 am – 12.00 pm
: 2 hours
: 1-9
: Electronics
Level of Study
Date
Course Code
: UG1
: 12/04/2014
: ECE 1312
This Question Paper Consists of Nine (9) 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 30% 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(10 marks)
a) Define active and passive components. Give two examples for each of the active and
passive components.
(3 marks)
b) One of the important semiconductor material properties is the bandgap energy.
i.
ii.
What is bandgap energy?
Semiconductor A has a bandgap of 1.1eV and semiconductor B has a bandgap
of 2.3eV. Which semiconductor material will have its current less affected
with temperature (is it semiconductor A or B)? Explain why.
(4 marks)
c) Calculate the majority and minority carrier concentrations in silicon at T = 300 K
when Na = 1017 cm-3 Assume, ni = 1.5×1010 cm-3 for Silicon.
(3 marks)
Question 2 (10 marks)
a) Silicon with an intrinsic carrier concentration of 1.5 × 1010 /cm3 is doped with
5 × 1017 atoms/cm3 of an element X. After doping, silicon becomes an n-type
material.
(5 marks)
i.
Give an example of element X.
ii. Calculate the electron and hole concentrations in the material at T= 300K.
b) Explain what happens to the carriers when p-type and n-type materials are put
next to each other, as shown in the Figure 2(b). Include the mechanisms involved
and the direction of the flow of electrons and holes.
(5 marks)
p
n
Figure 2(b)
Question 3 (10 marks)
a) Find the diode voltage VD and the battery voltage V, so that the current I = 0.4 mA for
the circuit in Figure 3 (a). Assume that the diode cut-in voltage V = 0.65 V. Also,
determine the power dissipated by the diode.
(5 marks)
Figure 3(a)
b) Determine the quiescent current, IDQ and the time varying current, id for circuit as shown
in Figure 3(b). Given that the circuit and diode parameters are VPS = 20V, R = 20k,
V = 0.65 V, and vi = 0.2 sin t.
(5 marks)
Figure 3 (b)
Question 4 (10 marks)
a) Plot the output voltage, vo for the circuit in Figure 4(a) for each V value. The input is
shown in the figure.
Assume
i.
V =0 V
ii.
V =0.65V
(5 marks)
Figure 4(a)
b) Calculate the common-emitter current gain β, collector current, IC and emitter current, IE
for a common-base current gain α = 0.95 and a base current IB = 35 µA. Assume the
transistor is biased in the forward active mode.
(5 marks)
Question 5 (10 marks)
For the transistor circuit shown in Figure 5, assume VBE(on) = 0.7V and β = 100.
Figure 5
a)
b)
Find the values of IBQ, ICQ, IEQ and VCEQ.
(5 marks)
Deduce the output load line equation for the circuit and sketch the load line by
showing the operating point (Q-point) of this transistor circuit.
(5 marks)