B.E. DEGREE EXAMINATION.
EC 152 — ELECTRONICS ENGINEERING
(Common to CH, TX, LT, BT, MT, TC, PT and F.T.)
Time : Three hours Maximum : 100 marks
Answer ALL questions.
PART A — (10 ´ 2 = 20 marks)
- What is doping? Why doping is needed?
- Define :
(a) Ripple factor
- Why biasing is necessary for transistor amplifier?
- Mention the features of power amplifier.
- Why FET is called as voltage operated device?
- Draw the characteristics of SCR and UJT.
- Why both the transistors cannot remain in active condition in a bistable multivibrator?
- Discuss about the concept of virtual ground in an OP–AMP.
- Convert the following :
(a) F 27H into decimal
(b) 10010012 into decimal.
- Reduce the following expressions :
PART B — (5 ´ 16 = 80 marks)
- Explain the following with suitable logic diagram.
(i) Clocked RS Flip–Flop.
(ii) D Flip–Flop.
(iii) JK Flip–Flop.
(iv) Clocked T Flip–Flop.
- (a) (i) Explain the mechanism of avalanche and zener break down in a
p–n junction diode.
(ii) Draw the energy band diagram of intrinsic and extrinsic semiconductor and explain them.
(iii) Draw the V–I characteristics of a semi–conductor diode and explain.
(b) (i) Draw the neat circuit diagram of a full wave rectifier and explain its operation.
(ii) Explain how regulation occurs in a Zener regulator for variable load.
- (a) (i) Explain the input and output characteristics of a transistor in CE configuration.
(ii) Describe the concepts of fixed bias, collector to base bias and voltage divider bias provided for a transistor.
(b) (i) Explain the classification of power amplifiers based on class of
(ii) With a circuit diagram, explain a single tuned amplifier.
- (a) (i) With a neat diagram, explain the operation of a n–channel JFET.
(ii) Explain about the two transistor analogy of SCR.
(iii) Describe the characteristics of diac and triac.
(b) (i) Explain with simple diagrams, the turn–ON and turn–OFF mechanism of switching transistor.
(ii) With a block schematic diagram, explain a temperature control system using negative feedback.
- (a) Explain with a circuit diagram, the operation of a transistorised RC phase shift oscillator.
(b) Explain with circuit diagram and suitable waveforms, the operation of a fixed bias transistor bistable multivibrator.