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SPPU Electronics and Telecom Engineering (Semester 3)
Electronic Devices & Circuits
December 2016
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Solve any one question.Q1(a,b) Q2(a,b)
1(a) Draw and explain the construction and working of N-channel JFET.
6 M
Solve any one question.Q1(a,b) Q2(a,b)
1(a) Find the current through ZL by using Thevenin's theorem in the circuit shown below:
!mage
6 M
1(b) Explain the following non-ideal V-I characteristics MOSFET:
i) Finite output resistance
ii) Subthreshold conduction
iii) Breakdown effects.
6 M
1(b) Explain and draw the quivalent and approximate circuit of the signle phase transformer referred to primary.
6 M

2(a) Determine the operating point (IDQ,
VDSQ of the JFET circuit as shown in figure(1). CalculateRS.
!mage
6 M
2(a) A 10 kVA transfromer has a full load efficiency of 96%. The copper loss and iron are equal Table given below shows the loading schedule of the transformer during a day. Calculate all day efficiency:
6 M
2(b) Draw the constructional diagram of N channel E-MOSFET and give drain and transfer characteristics for the same with necessary parameters.
6 M
2(b) State and explain: maximum power transfer theorem and Norton's theorem.
6 M

Solve any one question.Q3(a,b) Q4(a,b)
3(a) For the circuit diagram shown in Fig.2, determine the gm,
Av,
Ri,
Ro.
!mage
8 M
Solve any one question.Q3(a,b) Q4(a,b)
3(a) Derive the torque equation for D.C. motor. Draw the torque- current, speed-current characteristics of a shunt motor using torque equation or otherwise.
6 M
3(b) Write short note on constant current source using MOSFET.
4 M
3(b) Discuss briefly different methods of speed controol for three phase induction motors.
6 M

4(a) Explain the BiCMOS technology with suitable diagram.
6 M
4(a) Explain the difference between the squirrel cage induction rotor and slip ring induction rotor.
6 M
4(b) Explain how MOSFET can be used as Active resistor in VLSI circuits.
6 M
4(b) A 100 kW belt deriven D.C. shunt generator running at 500 rpm on 220 V supply, continues to run as a motor when the belt breaks. When it runs as a motor, it draws 12kW from supply. Find the speed at which it will run as a motor. The resistances of armature and field are 0.025Ω and 55Ω respectively. The total brush contact drop is 2 V.
6 M

Solve any one question.Q5(a,b) Q6(a,b)
5(a) Draw the different types of feedback topologies and compare their input and output impedances.
8 M
Solve any one question.Q5(a,b) Q6(a,b)
5(a) Explain the construction and working principle of BLDG motor. Also draw its speed torque characteristics.
7 M
5(b) Give the Barkhausen criterion and draw and LC oscillator circuit.
5 M
5(b) Write a short note on Reluctance motor.
6 M

6(a) For the circuit diagram shown in Fig.3, determine the G mf,
Avf,
Rif,
Rof.
!mage
8 M
6(a) Explain the construction and working principle of Universal Motor.
7 M
6(b) Differentiate RC and LC oscillator and draw RC phase shift oscillator using FET.
5 M
6(b) Distinguish between Brushless D.C. motor and Conventional D.C. motor.
6 M

Solve any one question.Q7(a,b) Q8(a,b)
7(a) Draw and explain block diagram of adjustable positive three terminal voltage regulator.
8 M
Solve any one question.Q7(a,b) Q8(a,b)
7(a) Explain the working principle of permanent magnet Stepper motor with constructional diagram.
7 M
7(b) Compare linear regulator and SMPS.
5 M
7(b) Draw and explain characteristics of D.C. Servomotor.
6 M

8(a) Explain SMPS using suitable block diagram.
7 M
8(a) Describe the principle of operation of single-phase split phase type induction. Motor along with its circuit and phasor diagram.
7 M
8(b) Design an adjustable voltage regulator using LM317 for output voltage 5-15 volts and draw necessary connection diagram. (Assume R1=240Ω and Iadjustable= 100 μA).
6 M
8(b) What is Stepper motor? Explain the concept of Stepper motor.
6 M

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