Theory Examination (Semester-II) 2015-16 ELECTRONICS ENGINEERING

This question paper evaluates understanding of semiconductor devices, diode characteristics, transistor biasing, FETs and MOSFETs, operational amplifiers, modulation, communication systems, CRO, digital meters, rectifiers, and waveform analysis.
It is divided into three sections focusing on definitions, analytical explanations, circuit-based questions, and communication theory.

SECTION – A (10 × 2 = 20 Marks)

This section contains brief conceptual questions requiring short explanations and simple calculations.
Topics include:

Breakdown mechanisms of diodes (Zener & Avalanche)

Dynamic forward and reverse resistance of PN junction

BJT as a bipolar device

FET as a voltage–variable resistor

OP-AMP differential amplifier output using differential gain & CMRR

Ideal characteristics of OP-AMP

Types of signals (analog, digital, periodic, aperiodic)

Total power in AM wave at 75% modulation

Role of triggering circuit in CRO

Lissajous pattern for frequency ratio f = 3f

This section tests fundamentals of devices, small computations, and conceptual clarity.

SECTION – B (5 × 10 = 50 Marks)

Students must attempt any five descriptive questions, including circuits, characteristics, and OP-AMP applications.

Topics include:

Op-amp circuits: output waveform and analysis

Block diagram of communication system; need for modulation

Transistor biasing: need & different biasing schemes

Calculation of IC & VCE for a given BJT circuit

Input/output characteristics of Common Base configuration

Op-amp applications: inverting, non-inverting, differential, voltage follower

CMOS inverter operation

Working of CRO with block diagram

Working of Digital Multimeter

This section checks circuit analysis, device characteristics, amplifier theory, and measurement techniques.

SECTION – C (2 × 15 = 30 Marks)

Students must attempt any two long-answer questions.

Topics include:

Rectifiers & Multipliers

Full-wave rectifier: circuit, operation & ripple factor derivation

Voltage multiplier circuits (doublers, triplers)

Difference between LCD and LED

MOSFET & BJT Biasing

Construction, working & characteristics of depletion-type MOSFET

Calculation of IB, IC, VCE, VB for a given BJT network

Zener diode regulation analysis (VL, VR, IR calculations)

Modulation Concepts

Power saving in SSB and suppressed carrier AM

Frequency deviation calculations for FM

Frequency measurement using Lissajous patterns

This section evaluates deep understanding, mathematical derivation, and practical electronics application.