About this previous year paper
The uploaded file is a B.Tech Semester III Theory Examination Paper (2018–2019) for the subject ELECTRONICS DEVICES AND CIRCUITS, with Subject Code REC 302.
The document contains 2 pages, carries a total of 70 marks, and the exam duration is 3 hours.
This question paper is designed for engineering students studying the fundamentals of semiconductor devices, diode and transistor behavior, MOSFET characteristics, amplifier circuits, oscillators, and electronic feedback systems. It tests both theoretical understanding and analytical thinking in electronic circuits.
PAGE 1 — OVERVIEW & CONTENT
Page 1 includes the exam header and SECTION A, which contains short-answer questions worth 14 marks (2 marks × 7 questions).
SECTION A Topics Include:
Semiconductors & Luminescence
Types of semiconductor materials used for luminescence effect (e.g., direct bandgap semiconductors like GaAs, GaN).
Diffusion of Carriers
Concept of carrier movement from high concentration to low concentration.
MOSFET Characteristics
Why MOSFET drain current in the linear region decreases with temperature increase.
Threshold Voltage
Basic definition and importance in MOSFET operation.
Zener Breakdown vs Avalanche Breakdown
The behavior of diodes under high reverse voltage.
JFET Small Signal Model
Diagram and explanation of small-signal parameters.
Transconductance
Meaning and role in amplifiers.
These questions test understanding of semiconductor physics and basic device concepts.
PAGE 2 — DETAILED QUESTIONS (SECTION C)
Page 2 contains long-answer questions worth 7 marks each. Students must attempt one part from each question group.
QUESTION 6 — MOSFET & Amplifier Design
(a)
Explain:
Single-stage MOS amplifier MOSFET internal capacitances such as:
Students must describe: Amplifier configuration
How capacitances affect frequency response Gain characteristics
Use of small-signal models
(b)
Draw and explain a biasing circuit of a MOSFET amplifier, including:
Circuit diagram Selection of Q-point
Voltage divider biasing Stability and linearity considerations
This question tests circuit design skills and understanding of MOSFET operation.
QUESTION 7 — Oscillators & Feedback Topologies
(a)
Draw the LC Oscillator circuit diagram and explain:
Tank circuit (L & C) Positive feedback requirement
Barkhausen Criterion for sustained oscillation Frequency of oscillation formula
(b)
Explain four feedback topologies with diagrams:
Students must describe:
How feedback improves amplifier performance
Effect on gain, bandwidth, stability, and distortion
OVERALL SUMMARY OF THE DOCUMENT
This exam paper thoroughly covers essential topics in analog electronics, including:
Semiconductor materials & carrier transport Diode & breakdown mechanisms
JFET small-signal modeling MOSFET device physics & biasing
Amplifier concepts Internal capacitances and AC response
LC oscillators Feedback topologies
The paper is ideal for:
B.Tech Electronics & Communication (ECE) Electrical Engineering
Computer Engineering (EC-related subjects)
Students preparing for exams or strengthening electronic fundamentals