JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRONIC CIRCUIT ANALYSIS Previous Question Paper (September/October - 2023 - R13)
Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.
Part A
An n number of stages are connected in cascade. Derive the expressions for the overall lower and higher cutoff frequencies.
Answer
For n identical stages, the overall lower cutoff frequency fL(n) is given by fL(n) = fL / sqrt(21/n - 1) and the overall higher cutoff frequency fH(n) is given by fH(n) = fH * sqrt(21/n - 1), where fL and fH are the cutoff frequencies of a single stage.
What are advantages of direct coupled amplifiers?
Answer
Direct coupled amplifiers have the following advantages: they have a simple circuit design due to the absence of coupling capacitors and transformers, they can amplify signals from DC up to high frequencies, and they are cost-effective and compact for integrated circuit fabrication.
Draw the frequency response of an CE amplifier.
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What is the relation between fT, fβ?
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What is effect of negative feedback on amplifier gain? Prove it
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Why LC Oscillators are not used at low frequencies?
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State the advantages of push-pull configuration.
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Classify the Power Amplifiers.
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What is the relation between Q factor and bandwidth?
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What is difference between single and staggered tuned amplifiers?
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Part B
Draw and explain the two stage amplifier with Darlington connection. Give the advantages of this circuit.
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An amplifier consists of 3 identical stages in cascade. The bandwidth of overall amplifier extends from 20 Hz to 20 kHz. Calculate the bandwidth of individual stage.
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Differentiate between direct and capacitive coupling of multiple stages of amplifiers. With the help of a neat circuit diagram, describe the working of a cascade amplifier.
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Determine the all hybrid –π parameters of a Transistor operating at Collector Current IC(Q) = 2mA, VCE(Q) = 20V and IB(Q) = 20μA.Transistor specifications are β0 = 100, unity gain frequency fT = 50MHz, COB=3pF, hie = 1.4KΩ, hre=2.5*10-4, hoe = 25μmhos. Assume that the Operating temperature is 300K.
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Discuss the effect of different types of loads to a common source MOS amplifier
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Explain the effect of coupling capacitor on frequency of an amplifier.
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Draw the current series feedback amplifiers with discrete components and derive for its gain, input impedance and output impedance.
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What are the effects of Feedback on input and output Resistances? Discuss.
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Draw the circuit diagram of Wein-bridge oscillator and explain its operation.
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In the Wein-bridge oscillator, if the RC network consists of resistors of 200K and the capacitors of 300pF, find its frequency of oscillation.
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Draw the circuit diagram of class B push pull power amplifier and derive an expression for its conversion efficiency.
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A single transistor is acting as ideal Class B amplifier with load of 1KΩ, if DC collector current is 10mA, VCC=30V. Determine its efficiency.
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Derive the expression for conversion efficiency of Class A transformer coupled power amplifier.
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Compare Series fed class A and transformer coupled class A power amplifier.
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Draw the circuit diagram of a Double tuned amplifier and derive the expression for 3-dB bandwidth.
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Draw and explain the circuit diagram of a single tuned capacitance coupled amplifier. Explain its operation.
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Explain the significance of Gain versus frequency curve of tuned amplifier. Draw the ideal and actual frequency response curves of single tuned amplifier.
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