# VTU Question Papers Basic Electronics

# Second Semester B.E. Degree Examination, May/June 2010

Note: 1. Answer any FIVE full questions.

- Standard notations are used.
- Missing data may be suitably assumed.

ESSr&v-‘ •

|fi>xplain the followings : i) Carrier concentrations in intrinsic semiconductor.

ii) Fermi level in a semiconductor having impurities. | What is Hall effect? Obtain an expression for the same.

Explain temperature dependence of V-I characteristics of P-N diode.

iDraw the bridge rectifier circuit and explain its working with waveform. (06 Marks)

Distinguish clearly Avalanche break down and Zener breakdown. (06 Marks)

£ An AC voltage of 110 V (RMS) is connected in series with a junction diode and a load ^resistor of 1.1 KQ. Compute :

iff) The peak current through diode ii) The peak output voltage. ^

^ 4 9 0 % • •

£$ssume that: i) the diode is ideal ; ii) The diode forward resistance is 15 O and forward

Voltage drop across it = 0.7 V. (08 Marks)

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\ Draw the output characteristics of a transistor in CE configuration. Indicate various regions |bf operation and explain the shapes of the curves qualitatively. (08 Marks)

Explain different types of distortions in amplifiers. (05 Marks)

fFor the circuit in Fig.Q3(c) shown below, determine the operating point. If Pd_{0} changes to a value of 50, find the new’ operating point. (07 Marks)

I \ 0 ^

Fig.Q3(c) ‘

Draw the oircuit of a RC coupled amplifier. Explain its frequency response characteristics.

= (08 Marks)

With a neat diagram, explain the working of a transistor Colpitt’s oscillator. Write the equation for frequency of oscillation. (06 Marks)

H^{c}– Explain the working of a Hartley oscillator, with a neat circuit diagram. (06 Marks)

ELN15/25

5 a. What is an OP Amp? List the characteristics of an ideal OP AMP. . (05 Marks)

- Explain how an OP AMP can be used for the following applications, with circuit diagrams and derive expressions for output voltages:

i) Integrator ii) Inverting amplifier iii) Voltage follower (10 Marks)

- Classify amplifiers based on: i) Function performed ii) Range of frequency

iii) Type of coupling iv) Mode of operation (05 Marks)

Draw a block diagram of a communication system. Explain function of each stage.(08 Marks) With suitable waveforms, explain the principle of frequency modulation. What arc its

advantages over amplitude modulation?

Define the following in case of practical OP AMP : i) Slew rate ii) CMMR iii) Off set voltages

(08 Marks)

(04 Marks)

- Perform the following conversion:

i) (1101)2 to ( ),_{0}

ii) (0.625)i_{0} to ( )_{2}

iii) (1026)g to ( )i_{0}

- State De Margan’s theorem and write the truth table for proving the theorem.
- Realize a-ftill adder using two half adders and an OR| gate.

8 a. Realize the following Boolean expressions using vaii) F = X_{1}Y-Z + XYZ + XYZ + XYZ + X

ii) F = AB +AB

- Distinguish clearly combinational logic circuit and
- Draw the block diagram of a CRO. Explain the functi