JNTU
JNTU B.Tech II Year ELECTRONIC CIRCUITS Previous Question Paper (November/December - 2017 - 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. Each question carries 10 marks and may have a, b, c as sub questions.
PART A
Discuss a small signal JFET model of a common drain amplifier.
Answer
The small signal model of a common drain (source follower) JFET amplifier replaces the FET with a voltage-controlled current source gmVgs in parallel with the output resistance rd. In this configuration, the gate is the input, the source is the output, and the drain is common to both input and output circuits.
List the benefits of H-Parameters.
Answer
- H-parameters are real numbers at audio frequencies, making them easy to measure.
- They are convenient for circuit analysis as they represent input impedance, current gain, reverse voltage gain, and output admittance.
- They allow for easy calculation of amplifier performance metrics like voltage gain, current gain, and input/output impedances.
Distinguish the negative feedback and positive feedback.
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Discuss how does negative feedback reduce distortion in an amplifier?
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What is cross-over distortion?
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Compare voltage and power Amplifiers.
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Describe about the double ended clipping.
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Define clamping. What for clamping circuits are used?
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Discuss about a Schmitt trigger.
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Name the methods of triggering in multivibrators? Distinguish between them.
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PART B
Evaluate the expression for Ri, Ai, Av and Ro for CE amplifier with un bypassed Re.
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State Millers theorems. Explain its significance in transistor circuit analysis.
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Classify the amplifier circuits based on frequency range, type of coupling, power delivered and signal handled.
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Define h-parameters? Why they called so? Define them and what are the benefits of h-parameters.
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Discuss the circuits of voltage shunt feedback amplifier and derive the expressions for input impedance Rif and output impedance Rof.
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Show that for voltage shunt feedback amplifier trans resistance gain, Ri and Ro are decreased by a factor (1+Aβ) with feedback.
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Explain the relevant information explain how the negative feedback improves stability reduce noise and Increase input impedance.
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With a neat sketch explain the working of a Colpitt’s oscillator.
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Evaluate the expression for maximum conversion efficiency for a simple series fed Class A power amplifier. What are the drawbacks of transformer coupled power amplifiers?
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With a neat diagram explain the principle of operation of class B pushpull amplifier.
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Define thermal resistance? Explain the thermal electrical analogy related to a transistor with heat sink.
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Explain and analyze a transformer coupled class A power amplifier and also define the total harmonic distortion with three point method.
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Sketch the response of an RC high-pass for square wave input.
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Explain the working of a simple diode comparator. Draw the output wave form for a ramp input.
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Explain the working of a transistor clipper. With the help of a neat circuit diagram and waveforms.
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Explain the response of an RC high-pass filter to behave as a good differentiator.
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Show that an astable multivibrator can be used as a voltage to frequency convertor.
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Evaluate an expression for the gate width of a monostable multivibrator.
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Explain the behavior of a BJT as a switch. Give Applications.
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Explain the phenomenon of “latching” in a transistor switch.
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