JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRONIC 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
How amplifiers are classified?
Answer
Amplifiers are primarily classified based on the following criteria:
- Based on the input signal: Small signal amplifiers (voltage amplifiers) and large signal amplifiers (power amplifiers).
- Based on the frequency range: Audio frequency (AF), radio frequency (RF), and direct-coupled (DC) amplifiers.
- Based on the coupling method: RC coupled, transformer coupled, and direct coupled amplifiers.
- Based on the operating point (biasing): Class A, Class B, Class AB, and Class C amplifiers, which are categorized by the portion of the input cycle for which the output transistor conducts.
Estimate the voltage gain and output voltage of an amplifier with negative feedback with A = 120, β = 0.05 and Vs = 75mV.
Answer
The closed-loop voltage gain (Af) of an amplifier with negative feedback is given by the formula:
Substituting the given values A = 120 and β = 0.05:
The output voltage (Vo) is calculated using the relationship Vo = Af × Vs. Given Vs = 75mV:
Develop the concept for drop in gain at the low frequency region and at the high frequency region.
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Evaluate unit gain frequency and β cutoff frequency.
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Draw a clipper circuit which clips all voltages above +2 V.
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Summarize the applications of bistable multivibrator.
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Draw the output characteristics of class A amplifier.
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Interpret the efficiency of Class C amplifier.
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List the Transistor Switching Times.
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What is the effect of temperature on reverse saturation current in a transistor?
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Part B
Compare the three CE, CB and CC amplifiers.
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Select and configure common-source amplifier with source resistor.
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Define positive and negative feedback.
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A Voltage-series negative feedback amplifier has a voltage gain without feedback of A = 500, input resistance Ri = 3kΩ, output resistance Ro = 20kΩ and feedback ratio β = 0.01. Find the voltage gain Af, input resistance Rif and output resistance Rof of the amplifier with feedback.
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Can you recall the operation of high frequency common source FET amplifier with neat diagram? Derive the expression for a) Voltage gain b) Input admittance c) input capacitance d) Output admittance.
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Summarize the expression for Low Frequency Analysis of BJT.
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What is the effect and significance of miller’s capacitance on the frequency response of an amplifier?
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Determine how Schmitt trigger circuit can be evolved from a bistable circuit.
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Evaluating the working principle of Bistable multivibrator with neat diagrams
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Design the transistor clipper with appropriate diagram and waveform.
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Calculate Vo for the clamping circuit for the given sinusoidal input signal shown in figure. Assume the sinusoidal input signal is 10Vpp.
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Write about the Class B transformer coupled power amplifier with necessary derivations.
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Summarize the transfer characteristic, signal waveforms, power dissipation, and power conversion efficiency of Class A amplifier.
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Demonstrate how a diode works as a switch and examine its piecewise linear characteristics?
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A rectangular pulse of voltage is applied to the base of a transistor, causing it to transition from cutoff to saturation. Explain how output potential has changed? Describe the various stages of the switching procedure.
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How should a transistor be designed as a switch? Describe the operational modes of a transistor switch.
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Identify and clarify the various diode switching times.
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