JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year ANALOG ELECTRONICS Previous Question Paper (November/December - 2018 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
What are the types of distortion in amplifiers.
Answer
The main types of distortion in amplifiers are linear distortion (frequency and phase distortion) and non-linear distortion (amplitude or harmonic distortion).
Classify the amplifiers according to the method of coupling.
Answer
Amplifiers are classified based on the coupling method as: 1) RC coupled (Resistance-Capacitance), 2) Transformer coupled, and 3) Direct coupled amplifiers.
Why the h parameter model is not suitable to analyze transistor at high frequencies.
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What are the elements in the Hybrid ‘Π’ model?
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What is cascode amplifier?
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State the advantages and disadvantages of the source follower.
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What is meant by positive and negative feedback?
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State the Barkhausen criterion for oscillations.
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What are the requirements of a tuned amplifier?
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Give the definition of power amplifier. Also list the types in it based on location of Q point.
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Part B
Draw the h-parameter equivalent circuit for a typical common emitter amplifier and derive expression for Ai, Av, Ri and Ro
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Draw simplified h parameter equivalent circuit and calculate Ai, Av, Avs, Ri' and Ro' for the cascode circuit shown in figure 1. Assume that transistors are identical with hfe=10, hie=2 KΩ, hre=hoe=0.
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Derive an expression for current gain with resistive load.
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The hybrid- Π parameters of the transistor used in the circuit shown in figure 2 are gm= 50 mA/V, rb'e=1 KΩ, rb'c=4 MΩ , rce=80 KΩ, Cc=3 pF, Ce=100 pF and rbb'=100 Ω, find (i) upper 3 dB frequency of current gain (ii) the Magnitude of voltage gain at Avs=V0/Vs at frequency of part (i)
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A single stage CE amplifier is measured to have a voltage gain bandwidth fH of 5 MHz with RL=500 Ω. Assume hfe=100, gm=100 mA/V, rbb'=100Ω, CC=1pF and fT=400 MHz. (i) find the value of source resistance that will give the required bandwidth. (ii) with the value of Rs found in (i), find the mid band voltage gain V0/Vs.
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In hybrid ‘pi’ model of a transistor at high frequencies, show that the gm is proportional to the collector current.
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Discuss the input and output characteristics of a folded cascade amplifier with NMOS input.
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Derive expression for Av and Ro for common gate amplifier.
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Draw and explain the CS stage with diode connected load.
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Discuss the MOSFET characteristics in depletion mode.
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Show that for a current series feedback amplifier the input and output resistances are increased by a factor if (1+Aβ) with feedback.
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Identify the topology of feedback in the circuit of figure 3 giving Justification. Two transistors are identical with hie=2 K and hfe=100. Calculate i)Rif (ii) Aif (iii)Avf
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Explain the principle of operation of the wein bridge oscillator.
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Mention the features and advantages of the crystal oscillator.
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Show that the transformer coupled class A amplifier maximum efficiency is 50%.
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Compare the push-pull class B and complementary symmetry class B amplifier.
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A tuned amplifier is required to have a voltage gain of 30 at 10.7 MHz with 200 KHz BW. An FET with gm=5 mA/V and rd=100 KΩ is available. Calculate the values of tank circuit elements.
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Draw and explain the frequency response of tuned amplifier.
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