Download Document

LOYOLA – ICAM
COLLEGE OF ENGINEERING AND TECHNOLOGY (LICET)
Loyola Campus, Nungambakkam , Chennai – 34
Branch: ECE
Semester: II
Date:24-04-2015
Time: 8.00 – 12.00 AM (3 Hrs)
MODEL EXAM
ELECTRONIC DEVICES (EC6201)
2.
Part-A (Answer all the questions)
(10x2=20)
The DC current gain (β) of a BJT is 50. Assuming that the emitter injection efficiency is
0.995, Find the base transport factor.
What is the principle of operation of a PN junction diode in forward bias condition
3.
Define Knee voltage of a diode.
4.
What is the need for biasing in the transistor
5.
6.
Define the amplification factor in the JFET. The built in potential of the gate junction of an
n-channel JFET is 0.9 volts. The drain current saturated at VDS = 3V when VGS = 0V. The
pinch off voltage
List out the applications of tunnel diode.
7.
What is tunneling phenomenon?
8.
Why Zener diode is often preferred than PN diode.
9.
Draw the basic structure of TRIAC and its symbol.
1.
10. Write down the significance of optocoupler
Part-B(Answer all the questions)
11.a.
(3x16=48)
Explain the theory of PN Junction Diode and derive its diode current equation
(16)
(OR)
b.
(i)Explain and derive current components.
(ii)Consider a silicon PN junction at room temperature having the following
parameters:
Doping on the N side = 2x1017 cm-3
Depletion width on N side = 0.1 µm
Depletion width on the P side = 1 µm
Intrinsic carrier concentration = 1.4x1010 cm-3
Thermal voltage = 26 mV
Permittivity of free space = 8.85x10-14 F/cm
Dielectric constant of silicon = 12.Find the built in potential & electric field
(8)
(8)
12.a. Present the circuit and explain the structure, operation and characteristics of (16)
CE, CB and CC configurations. Compare their parameters and performances.
(OR)
b.
(i) Discuss the Ebers-Moll Model of a PNP transistor
(16)
13.a
(ii) Derive the relationship between the transistor current gains α, β and γ with
necessary theory
(i) Discuss about FINFET and Dual Gate MOSFET
(8)
(i)Explain the four distinct regions of output characteristics of JFET
(8)
(OR)
b.
14.a
(i)With the help of suitable diagram explain the working of different types of
MOSFET
(ii)Briefly describe some applications of JFET
(i)Draw the VI Characteristics of Zener diode and explain its operation
(8)
(ii)Write short notes on Schottky diode
(8)
(8)
(8)
(OR)
b.
15.a
(i)Explain the principle behind the varactor diode and list out its application
(8)
(ii)Explain briefly about laser diode
Explain the operation ,characteristics and application of SCR
(8)
(16)
(OR)
b.
Write short notes on
(a) Solar Cell
(b) CCD
(8)
(8)
Branch:ECE
Semester: II
Date:DD/MM/2015
Time: 8.00 – 12.00 AM (3 Hrs)
MODEL EXAM
ELECTRONIC DEVICES (EC6201)
Part-A (Answer all the questions)
(10x2=20)
1.
Define mass action law
2.
What is the principle of operation of a PN junction diode in reverse bias condition
3.
Draw the h- parameter model for CB transistor
4.
What is “Early effect” in CB configuration
5.
When the gate to source voltage (VGS) of a MOSFET with threshold voltage of 410 mV.
The drain current observed is 1.5mA. Neglecting the channel length modulation effect, and
assuming that the MOSFET is operating at saturation, Find the drain current for an applied
VGS of 1400 mV.
6.
Draw the V-I characteristics curve of MOSFET
7.
Give the symbol and structure of schottky diode.
8.
Define Pinch off Voltage
9.
Draw the basic structure of DIAC and its symbol.
10. Write down the significance of optocoupler
Part-B(Answer all the questions)
(3x16=48)
11.a. (i)Explain how the depletion region at a p-n junction is formed and explain
with relevant sketches for charge density, electric field intensity and potential
energy barriers at the junction.
(ii)With necessary graph, explain the temperature dependence of V-I
(8)
(8)
Characteristics of a PN-junction diode.
(OR)
b.
Explain the theory of PN Junction Diode and derive its diode current equation
(16)
12.a. Explain the characteristics of BJT in CC,CE & CB configuration and compare the (16)
performance of a transistor in different configuration
(OR)
b.
(i) Discuss the Ebers-Moll Model of a PNP transistor
(8)
(ii) Derive the relationship between the transistor current gains α, β and γ with
necessary theory
(8)
(i) Discuss about FINFET and Dual Gate MOSFET
13.a
(i)Explain the four distinct regions of output characteristics of JFET
(8)
(8)
(OR)
b.
14.a
(i)With the help of suitable diagram explain the working of different types of
MOSFET
(ii)Briefly describe few applications of JFET.
(iii)The drain of an N channel MOSFET is shorted to the gate so that V GS = VDS.
The threshold voltage (VT) of MOSFET is 1 volt. If the drain current (ID) is 1 mA
for VGS = 2 volts, then for VGS = 3 volts.Find ID.
(i) .Explain the operation of tunnel diode and draw its equivalent circuit
(8)
(ii)Explain briefly about laser diode
(8)
(4)
(4)
(8)
(OR)
b.
(i)Explain the operation of varactor diode with a neat diagram
(8)
15.a
(8)
(ii) Discuss the V-I characteristics of Zener diode with a suitable diagram.
Explain the construction , operation, equivalent circuit V-I characteristics and (16)
application of UJT
(OR)
b.
Explain the construction , operation, equivalent circuit V-I characteristics and (16)
application of DIAC