**B.E./B.Tech. DEGREE EXAMINATION, APRIL/MAY 2010**

Third Semester

Electrical and Electronics Engineering

EE2203 — ELECTRONIC DEVICES AND CIRCUITS

(Regulation 2008)

Third Semester

Electrical and Electronics Engineering

EE2203 — ELECTRONIC DEVICES AND CIRCUITS

(Regulation 2008)

**PART A — (10 × 2 = 20 Marks)**

1. What is meant by diffusion current in a semi conductor?

2. A silicon diode has a saturation current of 7.5Î¼ A at room temperature 300°K.

Calculate the saturation current at 400°K.

3. Draw the input and output characteristics of a transistor in CE configuration

and mark the cutoff, saturation and active regions.

4. State the advantages of optocoupler. (Write any four).

5. Compare JFET with BJT.

6. Define amplification factor in JFET.

7. Define CMRR and write its significance in differential amplifiers.

8. List the advantages of negative feedback amplifiers.

9. Sketch the idealized characteristics for the filter types.

(a) Low pass

(b) High pass

(c) Band pass

(d) Band reject filters.

10. Define intrinsic stand off ratio of UJT and draw its equivalent circuit.

**PART B — (5 × 16 = 80 Marks)**

11. (a) With a neat diagram explain the working of a PN junction diode in forward bias and

reverse bias and show the effect of temperature on its V-I characteristics. (16)

Or

(b) (i) Explain V-I characteristics of Zener diode. (8)

(ii) Draw the circuit diagram and explain the working of full wave bridge rectifier and derive

the expression for average output current and rectification efficiency. (8)

12. (a) (i) Draw the h-parameter equivalent circuit of a transistor in CE configuration. (8)

(ii) Describe the methods of determination of h-parameters from its static Input and output

characteristics. (8)

Or

(b) (i) Explain the important characteristics of optocoupler. (6)

(ii) Explain the switching characteristics of transistor with neat sketch. (10)

13. (a) (i) Explain how the transconductance of a JFET varies with drain current and gate

voltage characteristics and transfer characteristics. (12)

(ii) A JFET has the following parameters IDDS = 32 mA, VGS(off) = -8 Volts, VGS = -4.5

Volts. Find the values of drain current. (4)

Or

(b) (i) Explain the working of n-channel enhancement type MOSFET.

Sketch its typical characteristics. (10)

(ii) Explain the application of FET as a voltage variable resistor. (6)

14. (a) (i) Draw the block diagram of a voltage series feedback amplifier and derive the

equation for input impedance, output impedance and the voltage gain. (10)

(ii) Calculate the voltage gain, input and output resistances of a voltage series feedback

amplifier having AV = 300, Ri = 1.5 k, Ro = 50 k and Î² = 1/15. (6)

Or

(b) (i) Differentiate oscillator with amplifier. (4)

(ii) Draw the circuit of a Hartley oscillator and derive the condition for the frequency of

oscillation. (12)

15. (a) (i) Describe the operation of UJT and its emitter characteristics. (8)

(ii) Describe the working of a Schmitt trigger circuit with the help of necessary waveforms.

(8)

Or

(b) (i) Sketch the response of RC high pass filter for the following inputs and explain.

(1) Ramp

(2) Pulse. (8)

(ii) Explain the operation of a bistable multi-vibrator circuit with neat sketch. (8)

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**EE2203 — ELECTRONIC DEVICES AND CIRCUITS QUESTION PAPER**