EC 1211 – ELECTRONIC DEVICES

PART A – (10×2=20 marks)

1.        What is meant by depletion region?

2.        Define the transition capacitance of a diode.

3.        What are power transistors?

4.        Which of the BJT configuration is suitable for impedance matching applications? Why?

5.        Define the pinch off voltage.

6.        Give the drain current equation of JFET.

7.        Differentiate a PN junction diode and LASER diode.

8.        List the application of opto-electronic devices.

9.        Draw the transistor equivalent circuit of SCR.

10. What is LDR?  

PART B – (5×16=80 marks)

11.      (a)      With the volt-ampere characteristics, explain the working principal of the diode and also explain the static dynamic resistance of the diode?                                                                                                              (16)

Or

            (b)      Write a detailed note on:

                        (i)       diode switching times.                                                               (6)

                        (ii)      applications of diodes.                                                               (4)

                        (iii)     Capacitance of diodes.                                                                (6)

12.      (a)      For common emitter-bipolar junction transistor configuration, analyze the input and output characteristics. Also, give the inference and necessary analytical expressions for the same.                                 (16)

Or

            (b)      Write a note on

                        (i)       Transistor construction.                                                            (4)

                        (ii)      Voltage gain and current gain expressions for CB Configuration using transistor hybrid model. (Figures are necessary)           (12)

13.      (a)      With neat diagram explain the construction, working characteristics of Unijunction transistor. Give its equivalent circuit.(16)

Or

(b)      Write the construction, operation and characteristics behavior of JFET under various biasing conditions. Give its equivalent circuit.(16)

14.      (a)      What is the physics of photo emissivity. Explain in detail, the construction and working of any one optoelectronic device which uses this principle.                                                                                                         (16)

Or

(b)      Give a detailed account on:

                        (i)       Opto couplers and their application.                                                (8)

                        (ii)      Photo transistors and diodes.                                                 (8)

15.      (a)      (i)       Define tunneling phenomenon. Explain how tunnel diode operates under different operating conditions. In what way it is different from the conventional diodes? Give the necessary energy level diagrams.                                                                                                                    (12)

(ii)      Give the characteristic features of devices belonging to the thyristor family.                                                                                                            (4)

Or

(b)      (i)       Zener diode can be used as a voltage regulator-justify it.(8)

                        (ii)      Write a note on PUT.                                                                   (8)