(SEM IV) THEORY EXAMINATION 2023-24 ELECTRONICS ENGINEERING

This document is a B.Tech (Semester IV) Theory Examination Question Paper for the subject BOE409 – Electronics Engineering, conducted in the academic session 2023–2024.
It is a 3-hour, 70-mark examination designed to evaluate students’ understanding of semiconductor devices, diodes, BJTs, op-amps, wave-measurement instruments, JFETs/MOSFETs, oscilloscopes, digital voltmeters, and electronic circuit concepts.

The exam consists of three sections:
SECTION A – Short conceptual questions
SECTION B – Medium-length analytical/theoretical questions
SECTION C – Long, diagram-based, and application questions

SECTION A – Short Answer Questions (14 Marks)

Seven 2-mark questions testing basic concepts:

PN Junction concept & formation                      Diode capacitance

Voltage multiplier circuits                                    BJT Q-point (operating point)

Common-Mode Rejection Ratio (CMRR) and effect on Op-Amp performance

Input offset voltage in Op-Amps                          Basic principles of Oscilloscope operation

This section examines fundamentals of semiconductor and instrument behavior.

SECTION B – Medium-Length Analytical Questions (21 Marks)

Attempt any three (7 marks each):

A. PN Junction Formation & Diode Resistance

Explains depletion region formation, majority/minority carriers, and how diode resistance varies under forward and reverse bias.

B. Voltage Multiplier Circuits

Working of voltage doublers, triplers, and cascade stages.

C. BJT Emitter-Bias Configuration

Bias stability, circuit structure, and functioning of emitter-stabilized transistor amplifier.

D. Op-Amp Block Diagram + Inverting Amplifier Design

Block diagram elements:

Differential amplifier                 Gain stages

Level shifter                               Output buffer

Plus design of inverting amplifier:
Gain = –5, Input resistance = 10 kΩ.

E. RAMP Technique in DMMs

Describes how Digital Multimeters use ramp signal conversion to measure voltage accurately.

SECTION C – Long Answer / Diagram-Based Questions (35 Marks)

Each question has two choices; answer one from each.

3. Zener Diode Breakdown / Zener Regulator (7 Marks)

Option (a) – Zener breakdown mechanism:

Avalanche breakdown                          Zener breakdown

Voltage stability characteristics

Option (b) – Zener diode voltage regulator:             

Students must determine VL, VR, IL, IR.

4. LED & LCD Concepts (7 Marks)

Option (a) – Operation, characteristics & applications of LEDs in lighting and display technology.

Option (b) – Operation and uses of LCDs, including twisted nematic effect and display segments.

5. JFET / Enhancement MOSFET (7 Marks)

Option (a) – Construction and working of N-channel JFET.
Option (b) – Construction & characteristics of Enhancement-mode MOSFET, threshold voltage concept.

6. Op-Amp Summing Amplifier / Differentiator (7 Marks)

Option (a) – Circuit diagram & output voltage derivation for summing amplifier.
Option (b) – Working of op-amp differentiator, frequency behavior.

7. CRO Measurements / Digital Voltmeter (7 Marks)

Option (a) – How voltage, current, phase, and frequency are measured using a Cathode Ray Oscilloscope (CRO).
Option (b) – Working principle of Digital Voltmeter (DVM) and advantages over analog voltmeters.

Overall Purpose of the Document

This exam paper evaluates a student’s competency in:

Semiconductor Devices

PN junctions, Zener diodes, LEDs, LCDs.

Analog Circuits

BJT biasing, op-amp circuits, summing amplifiers, differentiators.

Electronic Measurements & Instruments

CRO, DVM, RAMP technique in DMMs.

Field-Effect Devices

JFETs, MOSFETs – construction, operation, characteristics.

Electronic Circuit Analysis

Voltage multipliers, regulator circuits.

The paper includes definitions, diagrams, derivations, numerical analysis, circuit design, and operational principles of core electronic components—providing a comprehensive assessment of Electronics Engineering.