About this previous year paper
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.