Deemed University 2011 B.Tech Electronics and Communications Engineering University: Lingayas University Term: V Title of the : Electronics Engineering - Question Paper

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Lingayas University

B.Tech. 2^nd Year (Term V)

Examination Feb 2011

Electronics Engineering (EC - 201)

 

[Time: 3 Hours] [Max. Marks: 100]

 

Before answering the question, candidate should ensure that they have been supplied the correct and complete question paper. No complaint in this regard, will be entertained after examination.

 

Note: All questions carry equal marks. Attempt five questions in all. Question no. 1 is compulsory. Select two questions from Section B and two questions from Section C.

Section A

Q-1. Part - A

Select the correct answer of the following multiple choice questions. (10x1=10)

(i) p-type semiconductor material is:

(a) Silicon doped with indium (b) Silicon

(c) Silicon doped with arsenic (d) Germanium

(ii) n-type semiconductor is electrically:

(a) Positive (b) Negative

(c) Neutral (d) Both positive & negative

(iii) Leakage current of a junction diode:

(a) Is due to majority carrier

(b) Decreases with temperature

(c) Increases with temperature

(d) None

 

(iv) Which configuration is used as a voltage buffer?

(a) Common base (b) Common emitter

(c) Emitter follower (d) None

(v) Which one in the following has the highest input impedance?

(a) BJT (b) JFET

(c) MOSFET (d) Diode

(vi) In the negative feedback:

(a) Voltage gain increases (b) Voltage gain decreases

(c) Distortion increases (d) None

(vii) An oscillator circuit is mainly:

(a) dc to ac converter (b) dc to dc converter

(c) ac to dc converter (d) ac to ac converter

(viii) Which of the following h-parameter relation is not correct?

(a) hic = hie (b) hrc = 1 + hre

(c) hfc = - (1 + hfe) (d) hoc = hoe

(ix) For multistage amplifier as compare to signal stage:

(a) Voltage gain decreases (b) Bandwidth increases

(c) Bandwidth decreases (d) None

(x) For a transistor amplifier operating in the mid-frequency range:

(a) External capacitor are open circuit,

internal capacitor short circuit

(b) External capacitor short circuit,

internal capacitor open circuit

(c) External capacitor short circuit,

internal capacitor also short circuit

(d) None

 

Part B

(a) What is the significance of potential barrier in the pn junction? (5)

(b) Explain the concept of load line in FET. (5)

 

Section B

Q-2. (a) Explain the working of vacuum diode as half wave & full wave rectifier.

(b) Draw & explain the static characteristics of a triode. Also define the different parameters of triode. (2x10=20)

Q-3. (a) Explain the zener & avalance breakdown mechanism in diode.

(b) Discuss the both junction capacitances i.e. diffusion capacitance & depletion-region capacitance in detail. (2x10=20)

Q-4. (a) Draw & explain the working of centre-tap full-wave rectifier. Also derive the following:

(i) DC value of the current

(ii) RMS value of the current

(iii) Ripple factor

(iv) Efficiency (10)

(b) Explain the working of zener diode as a voltage regulator. (5)

(c) Draw & explain the LC filters for the rectifier circuits. (5)

 

Section C

 

Q-5. (a) Why the self bias circuit is more stable than other biasing. Explain.

(b) Draw & explain the output & input characteristics of the common-base configuration. What is early effect? (2x10=20)

Q-6. (a) Discuss the different type of biasing circuit for FET.

(b) Explain the current flow in the n-type JFET. Also draw its VI characteristics. What is pinch-off voltage?

(2x10=20)

 

Q-7. (a) Draw the common source amplifier & derive the expression for the voltage gain & output impedance.

(b) Give the comparison of transistors & thyristors. (2x10=20)

 

Q-8. (a) Explain the two transistors analogy of SCR. Also discuss the triggering process of SCR.

(b) Explain the working of UJT, draw its V-I characteristics. (2x10=20)