(SEM III) THEORY EXAMINATION 2021-22 ELECTRONICS ENGINEERING

This is the B.Tech Semester III examination paper for Electronics Engineering (KOE038) carrying 100 marks, designed to assess a student's understanding of the fundamental principles of semiconductor devices, diodes, transistors, operational amplifiers, and measuring instruments. The exam duration is 3 hours, and the paper is divided into three structured sections: A, B, and C.

SECTION A – Short Answer Questions (20 Marks)

This section includes 10 questions of 2 marks each, covering essential theory topics:

Doping and its purpose

Why silicon is preferred over germanium

Clipper vs clamper circuits

LED vs photodiode

BJT vs FET differences

Threshold voltage of MOSFET & IDSS of JFET

Unity gain amplifier (buffer)

Slew rate in op-amps

Analog vs digital instruments

Applications of Cathode Ray Oscilloscope (CRO)

These questions check basic conceptual knowledge of semiconductor and measurement fundamentals.
 

SECTION B – Descriptive / Analytical Questions (30 Marks)

Students must attempt any three out of five questions. These questions require explanation, circuit diagrams, and conceptual clarity:

Avalanche and Zener breakdown mechanisms

Tunnel diode and varactor diode

Common-base BJT structure, working, input & output characteristics

Operational amplifier block diagram, ideal characteristics, op-amp as an adder

Digital Storage Oscilloscope (DSO) block diagram and comparison with analog oscilloscope

This section tests analytical understanding, device physics, and circuit-level interpretation.

SECTION C – Long, Application-Based Questions (50 Marks)

Students must attempt one part from each question. This section contains numerical problems, circuit analysis, and device design:

Q3 – Diodes (10 Marks)

VI characteristics of ideal vs practical diode + diode equation

OR diode resistances + variation of transition & diffusion capacitances

Q4 – Zener Networks / Waveform Analysis (10 Marks)

Find IZ, IL, IR, VL of a Zener diode network (diagram on page 2)

OR determine output waveform from given diode-resistor circuit

Q5 – MOSFETs / BJTs (10 Marks)

Enhancement vs depletion MOSFETs, cross-section, transfer characteristics

OR NPN transistor construction, α & β, and their relationship

Q6 – Op-Amp Applications (10 Marks)

Virtual ground concept and op-amp differentiator

OR analyze output of given op-amp circuits (page 2–3)

Q7 – Instruments (10 Marks)

Measurement of voltage, frequency, and phase using CRO

OR working of Digital Multimeter with block diagram

This section evaluates problem-solving, device operation depth, waveform interpretation, and instrumentation knowledge.

 OVERALL SUMMARY

The Electronics Engineering KOE038 question paper covers:

Semiconductor physics (doping, diode behavior)

Special diodes (Zener, tunnel, varactor)

BJTs & FETs operation

MOSFET characteristics

Operational amplifiers (adder, differentiator, buffer, slew rate)

CRO, DSO, digital multimeter

Circuit analysis (Zener regulator, waveforms, op-amp circuits)

It is a comprehensive exam aimed at evaluating theoretical knowledge, circuit understanding, analytical skills, and practical electronics fundamentals required for core engineering subjects.