Electronics And Communication Engineering (Semester 3)
Total marks: 80
Total time: 3 Hours
INSTRUCTIONS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Draw neat diagrams wherever necessary.
PART-A
1.a.
Draw Zener Diode Characteristics.
(2 marks)
00
1.b.
Draw the Diode Equivalent Circuit. Mention the applications of PN-junction diode
(3 marks)
00
1.c.
Explain how P-N junction diode acts as a Rectifier.
(2 marks)
00
1.d.
Explain the necessity of filter circuit after the rectifier circuit.
(3 marks)
00
1.e.
Explain how transistor work as an amplifier.
(2 marks)
00
1.f.
Compare CE,CC and CB configurations.
(3 marks)
00
1.g.
What is the need of biasing?
(2 marks)
00
1.h.
Explain bias Compensation using Diodes.
(3 marks)
00
1.i.
Compare BJT and FET.
(2 marks)
00
1.j.
How FET acts as Voltage Variable Resistor?
(3 marks)
00
PART-B
Unit-I
2.a.
Explain the Avalanche and Zener Breakdowns in PN junction diode.
(5 marks)
00
2.b.
What is tunneling phenomena? Explain the principle of operation of tunnel diode with its characteristics.
(5 marks)
00
OR
3.a.
Derive the expression for transition capacitance of a diode.
(5 marks)
00
3.b.
Define varactor diode? Explain the operation of varactor diode with its equivalent circuit and mention its applications.
(5 marks)
00
Unit-II
4.
A sinusoidal voltage whose $V_m=26V$ is applied to half-wave rectifier. The diode may be considered to be ideal and RL=1.2 K$\Omega$ is connected as load. Find out peak value of current, RMS value of Current, DC value of current and Ripple factor.
(10 marks)
00
OR
5.a.
Derive the expression for Ripple factor for Full Wave Rectifier with L-section filter.
(5 marks)
00
5.b.
Compare FWR and Bridge rectifier.
(5 marks)
00
Unit-III
6.
The reverse leakage current of the transistor when in CB configuration is 0.3$\mu$A while it is 16$\mu$A when the same transistor is connected in CE configuration. Determine $\alpha$,$\beta$and$\gamma$
(10 marks)
00
OR
7.a.
Explain input and output characteristics of transistor in CB configuration with
neat diagram.
(5 marks)
00
7.b.
Discuss the base width modulation
(5 marks)
00
Unit-IV
8.a.
Derive the operating point using AC and DC load lines
(4 marks)
00
8.b.
Draw the circuit diagram of a voltage divider bias and derive expression for
Stability factor.
(6 marks)
00
OR
9.
Draw the circuit diagram of CC amplifier using hybrid parameters and derive the expression for $A_I,A_v,R_i$ and $R_0$
(10 marks)
00
Unit-V
10.
Explain the different biasing techniques of JFET.
(10 marks)
00
OR
11.
Describe the construction and working principle of Enhancement mode and depletion mode MOSFET and draw its characteristics.
(10 marks)
00
and 2 others joined a min ago.
