Janardan Rai Nagar Rajasthan Vidyapeeth 2006 B.Tech Electrical and Electronics Engineering ELETRONICS DEVICES AND CIRCUIT - Question Paper
JRN Rajasthan Vidyapeeth University
ELECTRICAL ENGINEERING
SEMESTER 4
ELETRONICS DEVICES AND CIRCUIT
Model Question Paper
BSCO7/BSE7/BSET7-ELETRONICS DEVICES AND CIRCUIT
Duration : 3 hrs Maximum Marks: 75
Instruction:
- Question paper is divided into Group A, Group B, and Group C
- Each Group is of 25 marks
- Figure to the right in bracket indicate marks.
- Good Handwriting is expected.
Group A (25 Marks)
Answer any three questions (Question 1 is compulsory)
Q.1 Write a short note on the importance of half power points in the frequency response curve of an amplifier. (5)
Q.2 Draw the circuit diagram of a push - pull amplifier circuit. (10)
(a) How proper biasing is achieved in this circuit and .
(b) How ac power, free from even harmonies is developed across the load.
Q.3 How an op amp is used as an. (10)
(1) Inverting amplifier.
(2) Non Inverting amplifier.
Q.4 Explain transistor R.C coupled amplifier with special reference to frequency response.
Write its advantage and disadvantages. (10)
Q.5 Draw the circuit of class c transformer coupled tuned amplifier using one transistor and describe its working . (10)
Group B (25 Marks)
Answer any three questions (Question 6 is compulsory)
Q.6 In the phase shift oscillator ,R1 = R2 = R3 = 1MΩ and C1 =C2=C3=68pf. At what freq
does the circuit oscillate ?
Q.7 Determine the (i) Operating Frequency (ii) feedback fraction For (i) Culprits oscillator (ii) Hartley oscillator. (10)
Given data :- C1 = .001μF ,C2= .01μF ,L1 = 1000μH , L2 =100 μH
M=20μH, L=15μH, , C = 20PF.
Q.8 The positive shunt dipper shown in fig.1 has the input wave form as indicated. Determine the value of Vout for each of the input alternations. (10)
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vin
R
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vin 200Ω
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+10v
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RL = 1KΩ
volt
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0
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-10v
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Q.9 In a differential amplifier of the type shown in figure R1 = 10Kg , R2 = 100KΩ ,R3 = 10KΩ and R4 =100k dΩ . Calculate the output voltage of the circuit if (i)V1 = 10mv , V2 =0 .(ii) V1 = 0,V2=10mv. (iii) V1 =100mv ,v2=50mv (iv) V1=50mv , V2 =1mv. (10)
R2
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R1
V1
Vout
V2 1
R3
R1
Q.10 A silicon transistor has collector leakage current of 1A for = 40V. If Vknee =1.2V. VBE = 0.6V for Ic = 100mA. Find (10)
(i) Saturation current for a load of 600 Ω for vcc =48Ω
(ii) Power amplification
(iii) Ratio of full load to no-load current through load .Given β=300.
Group C (25 Marks)
All questions are compulsory.
Q. 11. Fill in the blanks (Each question carries 2 marks, Total = 10 marks)
(a) Ina a multistage amplifier, if the gain of 3 stages is 10db, 5dB & 6dB then the overall gain will be.
(b) Class ____________ power amplifier has the biggest collector efficiency.
(c) Emitter follower is used for _____________]
(d) The input impedance of an op-amp is very _______.
(e) The output voltage of a 7812 IC voltage regulator is ________ volts.
Q. 12. Multiple choice questions (Each question carries 2 marks, Total = 10 marks)
Select the correct answer.
(1) The final stage of an amplifier uses.
(a) R-coupling (b) Transforming coupling (c) direct coupling (d) All of these.
(2) In push pull amplifiers , usually biasing is not required because
(a) dc batter Vcc is employed (b)Power transistor do not require biasing (c) Heat sink is used with the transistors. (d) Transistors are working in class B operation.
(3) Both positive and negative feedback employed in
(a) Hartley oscillator(b) Colpilts oscillator(c) Wein bridge oscillator (d) R.C phase shift oscillator.
(4) A circuit that generates square wave is called.
(a) an oscillator (b) a multivibrator (c) a modulator (d) a differentiator.
(5) ideal opamp is
(a) finite (b) zero (c) infinite (d) unity.
Q. 13. Indicate whether following statements are True or False (Each question carries 1 marks, Total = 5 marks)
(1) In transistor amplifiers . We use step up transformer for impedance matching.
(2) Feedback circuit is strongly dependent on frequency .
(3) One condition for oscillation is a phase shift around the feed back loop of 180◦.
(4) At parallel resonance , the ration L/C is very large.
(5) An astable multivibrator has one astable state.
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| Earning: Approval pending. |
