Hall Ticket No Question Paper Code: AEC001
INSTITUTE OF AERONAUTICAL ENGINEERING
(Autonomous)
Four Year B.Tech III Semester End Examinations (Supplementary) July, 2018
Regulation: IARE R16
ELECTRONIC DEVICES AND CIRCUITS
Time: 3 Hours (Common to ECE EEE Max Marks: 70
Answer ONE Question from each Unit
All Questions Carry Equal Marks
All parts of the question must be answered in one place only
UNIT I
1. Explain the static and dynamic resistance of a diode with relevant expressions. Illustrate the two
breakdown mechanisms in a diode with relevant example and figure.
Determine the germanium PN junction diode current for the forward bias voltage of 0.2V at
room temperature 240C with reverse saturation current equal to 1.1mA. Take
2. What is a Zener diode? Explain the construction, working and VI characteristics of Zener diode.
Illustrate how Zener diode is used a voltage regulator with example and relevant figure
Determine the forward resistance of a silicon PN junction diode when the forward current is
5 mA at room temperature.
UNIT II
3. Calculate the ripple factor for the half wave rectifier with a shunt capacitor filter.
A half wave rectifier is used to supply 24V D.C power to a resistive load of 500
and the diode
has a forward resistance of 50
. Calculate the maximum value of the A.C. voltage required at
the input.
4. A full-wave rectifier is connected with capacitive filter. Derive expression for the ripple factor
and draw relevant waveforms
A full wave rectifier has a center tapped transformer 100-0-100 V. Each one of the diode is rated
at Imax of 400 mA and Iav of 150 mA. Neglecting the voltage drop across the diodes, find
i. The value of the load resistance that give the largest DC power output
ii. DC output voltage
iii. DC load current and
iv. PIV of each diode
UNIT III
5. Highlight the need and importance of JFET. Compare the salient features of JFET and bipolar
junction transistor(BJT).
Compare and contrast JFET with MOSFET? Draw the symbols of MOSFETs.
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6. Illustrate the common base configuration of BJT with relevant figures and explain its input and
output characteristics.
A transistor operating in CB configuration has IC 2.98mA, IE 3.0mA and Ico 0.01mA.
What current will flow in collector circuit of that transistor when connected in CE configuration
and base current is 30A
UNIT IV
7. Explain the two important factors to be considered while designing the biasing circuit which are
responsible for shifting the operating point. Also list the requirements of a biasing circuit.
Explain the construction and operation of N-channel enhancement type MOSFET with the help
of its(ID-VDS) and characteristics.
8. Discuss the need to fix the operating point of a transistor and illustrate the DC load line analysis
of common emitter output characteristics of BJT.
A collector to base circuit shown in Figure 1 has VCC 24 RB 180 K
RC 3.3 K
and
VCE 10 V. Calculate hFE. Determine VCE when a new transistor is replaced having hFE
120
Figure 1
UNIT V
9. Draw the small signal equivalent circuit of the source follower circuit and derive the equations
for voltage gain, input admittance and output admittance.
For the circuit shown in Figure 2 below, VCC 20 RC 2 k
 50, VBEact 0.2 R1
100 k
R2 5 k
and RE 100
. Calculate IB, VCE and IC.
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Figure 2
10. Classify the amplifiers based on biasing conditions.
In the common gate amplifier, RD 2 K
gm 1.43 x mho and rd 35 K
. Evaluate
the voltage gain AV.