Download AKTU B-Tech 1st Sem 2015-2016 NEC 101 Electronics Engineering Question Paper

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NEC-101

(Following Paper ID and Roll No. to be filled in your Answer Book)

Paper ID: 131101

Roll No.

B. Tech.

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(SEM. I) THEORY EXAMINATION, 2015-16

ELECTRONICS ENGINEERIING

[Time: 3 hours]

[Total Marks: 100]

Section - A

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1. Attempt all parts. All parts carry equal marks. Write answer of each part in short. (2x10=20)
   1. Explain the effect of temperature on conductivity of a semiconductor.
   2. Define CMRR, slew rate of OPAMP.
   3. A 320W carrier is simultaneously modulated by two audio waves with modulation % of 45 and 60 respectively. What is the side band power radiated?
   4. Define signal. Name various types of signal.
   5. Why Si is preferred over Ge for manufacturing of electronics devices.

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   6. In JFET Idss = 8mA, Vp = -4V biased at VGS = -1.8V. Determine the value of gm.
   7. Define OP-AMP and draw its block diagram.
   8. Explain FET as Voltage Variable Resistor (VVR).
   9. Explain with proper reason the use of Emitter Follower.

      Vo

      R_L = 0.22 kO

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   10. Define Depletion layer of PN junction diode.

Section - B

Attempt any five questions from this section : (10x5=50)

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2. (a) Determine Vo and draw the output waveform of the given network of fig. 1
   (b) For the network of fig. 2 determine the range of Vi that will maintain Vo at 8V and not exceed the maximum power rating of the Zener diode.

   Pzmax = 400 mW

   V_Z=8V

   V_i

   5v

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   Ideal

   20 V

   -20 V

   Figure 1

   Figure 2

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3. (a) Sketch vo, Vdc for the network of fig. 3 and determine the peak inverse voltage of each diode.
   (b) Sketch Vo for each network of fig. 4 for the input shown.

   V

   100 v

   Ideal Diodes

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   - 100 v

   Figure 3

   Figure 4

4. Explain with the help of necessary diagram :
   1. Inverting Amplifier

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   2. Integrator
   3. Differential amplifier in two mode of operation
5. Define Modulation. Derive the relation of total power of AM waves.
6. For the voltage divider configuration of fig.5 determine re, Av, Zin and Zo
   

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   (b) Find out the voltage Vo and V2 of the given network of fig.6.

   ß = 90

   Figure 5

   Figure 6

7. (a) Determine the output voltage of an op-amp for input voltages of Vi1=200V and Vi2=140V. The amplifier has a differential gain of Ad = 6000 and the value of CMRR is : (i) 200 (ii) 105

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8. With the help of neat block diagram explain the working of a CRO.
9. Explain with the help of neat diagram working and characteristics curve of Ramp type digital voltmeter.

Section - C

Attempt any two questions from this section: (15x2=30)

10. (a) Explain working and characteristics of Tunnel diode with the help of neat diagram.
    

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    (b) Describe with the help of circuit diagram working of voltage tripler.
    (c) Differentiate between Half wave and Full wave rectifiers.
11. (a) Explain construction and working and characteristics of P channel Enhancement MOSFET.
    (b) Draw and explain the input and output characteristics of Common Emitter configuration.
    (c) For an input of V1 = 50mV in the mcircuit of fig. 7, determine the maximum frequency that may be used. The op-amp slew rate SR = 0.4 V/s.
    

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    (b) Determine Zi, Zo and Av for the network of fig. 8 Idss = 12 mA, Vp = -6 V, and Yos = 40 micro Siemens.

    Figure 7

    Figure 8

12. Explain the need of modulation in communication system.
    (a) A 460 watt carrier is modulated to a depth of 65 percent. Calculate the total power in the modulated wave.

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