JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year ELECTRONIC DEVICES AND CIRCUITS Previous Question Paper (April/May - 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
Define Early Effect.
Answer
The Early Effect (or base-width modulation) is the variation in the effective width of the base in a BJT due to changes in the collector-to-base reverse-bias voltage. As the reverse bias increases, the depletion region widens, narrowing the neutral base region and increasing the probability of charge carrier recombination.
What is meant by Depletion Region?
Answer
A Depletion Region is a zone near a p-n junction where mobile charge carriers (electrons and holes) have diffused away, leaving behind immobile ionized donor and acceptor atoms. This region acts as an insulating barrier, creating an internal electric field that prevents further diffusion of carriers across the junction.
What are the Harmonic components in a Rectifier?
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Define Percentage of Regulation.
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Draw the diode equivalent model of a transistor.
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Find the value of β if a transistor has α = 0.97. Also find α if β=200.
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What is Thermal runaway in transistors and mention how it can be avoided?
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Why a capacitive coupling used to connect signal source to an amplifier.
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Differentiate the FET operation in enhancement and depletion modes.
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Why the input impedance of FET is higher than BJT?
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PART - B
Draw and explain the graph indicating the variation of minority carrier density with distance in a p-n junction diode under forward biased condition.
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Derive expression of space charge capacitance CT for a step graded junction.
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Derive the expression for Diffusion Capacitance.
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Discuss the static characteristics of SCR with a neat diagram.
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Derive the expression for ripple factor of Half wave rectifier with C-filter.
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A full-wave single phase rectifier employs a π- section filter consisting of a pair of 5 μF capacitances and a 20 H choke. The transformer voltage to the center tap is 200 V rms. The load current is 600 mA. Calculate the dc output voltage and the ripple voltage. The resistance of the choke is 300Ω.
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Derive Vdc, Vrms and PIV for the circuit of a Full-wave rectifier and explain its operation.
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Describe the working of a Zener Diode as a Voltage Regulator.
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With a neat diagram, explain the operation of BJT and discuss about the different configurations.
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Explain the hybrid small signal model for common collector configuration.
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With neat diagram, explain the input and output characteristics of a transistor in CE configuration.
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Describe the operation of UJT as relaxation oscillator.
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Explain DC load line and Q point for any transistor configuration. Also state the necessity of biasing and list biasing methods for transistor.
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Determine the quiescent currents and the collector to emitter voltage for a Ge transistor with β = 50 in the Self biasing arrangements. The circuit component values are VCC = 20V, RC = 2kΩ, RE = 0.1 kΩ, R1 = 100 kΩ and R2 = 5 kΩ. Find the stability factor S.
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Draw and explain self-bias circuit. Mention its advantages over fixed bias circuit.
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Describe the analysis of Transistor Amplifier circuit using h-parameters.
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Illustrate the construction and operation of p-channel JFET with neat diagrams.
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With neat sketch, discuss the working of a common source FET amplifier.
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With neat sketch, describe the working principle, operation and characteristics of the N-channel Enhancement mode MOSFET.
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Explain how JFET works as a Voltage Variable Resistor?
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