About this previous year paper
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.