Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II ELECTRONIC CIRCUITS Previous Question Paper (May/June - 2019 - 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.
Part A
Three amplifiers of gain 10dB, 20dB and 30dB are connected together. Find the overall gain in dB and in normal units.
Answer
When amplifiers are connected in cascade, the overall gain in decibels (dB) is the sum of the individual gains. Therefore, the overall gain in dB is:
To find the overall gain in normal units (Atotal), we use the relationship AdB = 20 log10(A). Rearranging this gives A = 10(AdB/20):
Why is non-linear distortion called Harmonic distortion.
Answer
Non-linear distortion is referred to as harmonic distortion because the non-linear transfer characteristic of an electronic device, such as a transistor or vacuum tube, causes the output signal to contain frequency components that are integer multiples of the input signal frequency. When a pure sinusoidal input signal of frequency f is applied to a non-linear system, the output includes the fundamental frequency along with higher-order harmonics at 2f, 3f, and so on. These additional frequencies are generated mathematically by the power series expansion of the non-linear transfer function, which transforms the input sine wave into a complex waveform containing these harmonic components.
Why LC oscillators are not used at low frequencies.
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An amplifier with a bandwidth of 20Hz to 20Khz is available. Find the overall bandwidth of a feedback amplifier, if A=30dB and feedback factor is 0.2.
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What is cross over distortion?
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Classify power amplifiers.
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Relate clipper with an attenuator.
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State the clamping theorem.
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Write the application of Monostable multi-vibrator.
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What is a multivibrator? List different types of multivibrators.
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Part B
Describe the effect of coupling and bypass capacitors on low-frequency response of BJT Amplifiers. Derive the corresponding equations.
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Derive the expressions for voltage gain, current gain, input and output resistances of a CB Amplifier.
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Explain the method of analysis of feedback amplifier.
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Calculate the voltage gain, input impedance and output impedance of a voltage series feedback amplifier having an open loop gain A=300, Ri=1.5KΩ, R0=50KΩ and β=1/20.
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Draw the circuit of Hartley oscillator and explain its working. Derive the expression for frequency of oscillation and condition for sustaining of oscillations.
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What is Class B amplifier? Derive the expression for its efficiency.
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Draw and explain the operation of Transformer coupled class-A power Amplifier. Also compare this with series-fed class-A power Amplifier.
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Explain the operation of a class A power amplifier with necessary diagram.
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In an Ideal Class B push pull amplifier, VCC=20V, N2=2N1 and RL=20 ohms. Find the output signal power, P0max and collector dissipation in each Transistor, PC under full power condition, find PCmax also.
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Obtain the transfer characteristic for the clipper circuit shown in figure 1.
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Obtain the transfer characteristic for the clipper circuit shown in figure 2.
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Explain the principle of clamping and also discuss the need for shunt resistor in parallel with the diode in the basic clamping circuit.
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Find the expression for output voltage when a ramp signal is applied to a RC Low Pass filter circuit.
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List and explain different switching times of diode.
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A rectangular pulse of voltage is applied to the base of a transistor driving it from cutoff-to-saturation. Discuss the changes in output potential. Explain the various times involved in the switching process.
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Design an astable multivibrator, to generate a square wave of 2KHz frequency with a duty cycle of 35%.
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Design a Bistable Multivibrator if VCC=VBB =11V. The DC current gain of each Transistor is 30.
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