(SEM III) THEORY EXAMINATION 2018-19 ELECTRONICS DEVICES AND CIRCUITS

The uploaded file is a B.Tech (Semester III) Theory Examination – 2018–2019 question paper for the subject ELECTRONICS DEVICES AND CIRCUITS, Sub Code REC 302.
It contains 2 printed pages, carries a total of 70 marks, and is meant to be completed in 3 hours.

The paper examines a student’s understanding of semiconductor physics, electronic devices, MOSFET behavior, BJT parameters, amplifier analysis, and oscillator design. It includes both theoretical and analytical questions that test conceptual depth and practical knowledge.

PAGE 1 OVERVIEW

Page 1 contains the exam instructions and SECTION A.

SECTION A — Short Questions (2 × 7 = 14 Marks)

Students must answer all seven brief questions.
These questions focus on fundamental definitions and basic semiconductor concepts.

Topics include:

Semiconductors suitable for luminescence effect (LED-type materials)

Diffusion of carriers

Temperature effect on MOSFET drain current in linear region

Threshold voltage meaning

Zener breakdown vs Avalanche breakdown

Small signal model of JFET

Transconductance definition and importance

These questions check basic understanding of semiconductor device physics.

SECTION B — Medium-Length Questions (7 × 3 = 21 Marks)

While not fully visible in the scanned image, Section B typically targets:

Diode characteristics                          BJT configurations

Load-line analysis                               Biasing techniques

Frequency response of amplifiers      MOSFET operation regions

This section tests a student’s analytical ability and theoretical knowledge.

PAGE 2 OVERVIEW

Page 2 provides SECTION C, which contains long, circuit-oriented and design-based questions requiring detailed explanations, diagrams, and mathematical reasoning.

SECTION C — Long Questions (7 marks each)

Students must attempt any one part of questions 6 and 7.

Question 6 — MOSFET Amplifiers & Capacitances

(a)

Explain in detail:

Single-stage MOS amplifier              MOSFET internal capacitances (Cgs, Cgd, Cds)
Including:

Small-signal model                              Frequency response implications

Gain characteristics

(b)

Draw and explain a biasing circuit of a MOSFET amplifier.
Students must include:

Circuit diagram                                    Operating point (Q-point) selection

Load line                                              How biasing stabilizes amplifier performance

This tests design ability and MOSFET theory.

Question 7 — Oscillators & Feedback Topologies

(a)

Draw the circuit diagram of an LC oscillator and state the Barkhausen criterion (condition of oscillation).
Explanation must include:

Tank circuit (L and C)                            Positive feedback

Frequency of oscillation formula

(b)

Explain four types of feedback topologies using schematic diagrams:

Voltage-series                               Voltage-shunt

Current-series                               Current-shunt

Students must describe:                Input/output sampling

Mixing method                              How feedback influences gain, bandwidth, distortion

OVERALL SUMMARY

The ELECTRONICS DEVICES AND CIRCUITS exam paper covers:

Semiconductor fundamentals

Carrier mechanisms

Diode & Zener behavior

BJT & MOSFET device physics

Amplifier theory & design

Biasing circuits

Oscillators

Feedback systems

It is ideal for engineering students preparing for electronics exams, competitive tests, or strengthening their foundational understanding of analog electronics.