JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II ELECTRONIC CIRCUIT ANALYSIS Previous Question Paper (February - 2024 - R15)
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
Draw the simplified h-parameter model of CE amplifier.
Answer
The simplified h-parameter model for a Common Emitter (CE) amplifier assumes that the reverse voltage transfer ratio (hre) is negligible (hre ≈ 0) and the output admittance (hoe) is negligible (hoe ≈ 0). The model consists of an input circuit with a base resistor hie in series with the input voltage, and an output circuit represented by a dependent current source of value hfeIb connected in parallel with the output terminals.
In this model, the input terminals are base and emitter, while the output terminals are collector and emitter, with the emitter acting as the common terminal.
State and derive equivalent input, output impedance of Miller’s theorem
Answer
Miller's theorem states that a floating impedance Z connected between two nodes with a voltage gain A = V2/V1 can be replaced by two grounded impedances Z1 and Z2 connected at the input and output nodes respectively. The equivalent impedances are given by Z1 = Z / (1 - 1/A) and Z2 = Z / (1 - A).
To derive these, consider a current I flowing through impedance Z from node 1 to node 2. The voltage across Z is V1 - V2. Since V2 = A*V1, the current is I = (V1 - V2) / Z = V1(1 - A) / Z.
The input impedance Z1 is defined as V1 / I1. Since the current entering node 1 is I, Z1 = V1 / (V1(1 - A) / Z) = Z / (1 - A). Note that if A is defined as V2/V1, the standard form is Z1 = Z / (1 - A) and Z2 = Z / (1 - 1/A).
For the output impedance Z2, consider the current I2 flowing into node 2. I2 = (V2 - V1) / Z = V2(1 - 1/A) / Z. Thus, Z2 = V2 / I2 = Z / (1 - 1/A).
What is the role of bypass capacitor in BJT CE-amplifier circuit?
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Discuss about the Gain bandwidth product.
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State Barkhausen criteria for oscillation.
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Compare positive feedback and negative feedback.
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State the advantages of push-pull configuration.
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Discuss about series fed class A power amplifier?
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What is use of transformer in tuned amplifier circuit?
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What is Heat-sink? Classify the different types of Heat sinks.
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Part B
Derive the expression for current gain, input resistance, voltage gain and output resistance of CB amplifier using simplified h parameter model.
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In a single stage CE amplifier RS=1 KΩ, R1=50 KΩ, R2=2 KΩ, RC=1 KΩ, RL=1.2 KΩ, hfe=50 and hie=1.1KΩ. Find AI, Ri, Ro and AV.
Answer
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Derive the expressions for higher and lower cut-off frequency of a multistage amplifier.
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Derive expressions for overall voltage gain and overall current gain of a two stage RC coupled amplifier.
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Derive the expression for the CE short circuit current gain at high frequencies.
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Derive the voltage gain equation for emitter follower amplifier at high frequencies.
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Derive the expressions for hybrid pi conductance of CE transistor at high frequencies.
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Explain the small signal model of MOS transistor?
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Explain the principle of negative feedback in amplifiers. Show quantitatively the effect of negative feedback on (i) Gain (ii) Stability (iii) Noise (iv) Distortion.
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Draw the circuit diagram of voltage series feedback amplifier and derive expressions for input and output resistances.
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Explain the concept of frequency and amplitude stability of oscillators.
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Derive an expression for frequency oscillation of Hartley oscillator using transistor.
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What is meant by distortion in power amplifiers? Discuss crossover distortion.
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Show that the maximum conversion efficiency of a push-pull class-B power amplifier is 78.5%.
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Derive the expression for the harmonic distortion in a power amplifier.
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Draw and explain complementary symmetry class B push-pull amplifier.
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Derive an expression for bandwidth of an n-stage synchronously tuned amplifier.
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Draw the circuit of single tuned capacitance coupled amplifier and explain its operation.
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Discuss the necessity of stabilization circuits in tuned amplifiers.
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Draw the circuit of staggered tuned capacitance coupled amplifier and explain its operation.
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