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

This question paper evaluates a student's understanding of semiconductor devices, diode circuits, transistor configurations, FETs, MOSFETs, operational amplifiers, CRO, power supplies, and rectifiers.
It is divided into three sections covering conceptual definitions, analytical explanations, and detailed device-level derivations.

SECTION – A (10 × 2 = 20 Marks)

This section contains ten short-answer questions requiring definitions, comparisons, small calculations, or circuit sketches.
Topics include:

Properties of Si vs Ge semiconductors

Depletion layer in a diode

Bulk resistance of a diode

Double-ended diode clipper circuit

Output waveform across RL (given op-amp protective circuit)

Source transformation (voltage source → current source)

Ohmic region in FET

Percentage change in β for change in α

Need for triggering in CRO

Specifications of unregulated power supply

This section tests basic semiconductor theory, small derivations, and device fundamentals.

SECTION – B (5 × 10 = 50 Marks)

Students must attempt any five descriptive questions involving diagrams, device characteristics, amplifier analysis, and op-amp applications.

Topics include:

Input & output characteristics of Zener and Varactor diodes

Common Base transistor configuration and Voltage Divider Bias

Loading effect due to amplifier input impedance

JFET transconductance curve

Self-bias JFET amplifier circuit

CMOS inverter working

Op-amp applications: integrator, summing amplifier, zero-crossing detector

Voltage gain, input impedance & bandwidth of inverting amplifier with negative feedback

Characteristics of Digital Voltmeter

CRO controls and measurement of power supply performance

This section evaluates device behavior, circuit analysis, biasing, op-amp design, and instrumentation understanding.

SECTION – C (2 × 15 = 30 Marks)

Students must attempt any two long-answer questions.

Topics include:

Half-Wave Rectifier

Derivation of ripple factor

Analysis of the given diode clipping circuit (Fig. 2) with output waveform

Transistor & MOSFET

CE configuration: circuit, input/output characteristics

Working of enhancement and depletion-mode MOSFET

Derivation of JFET transconductance (gₘ) equation

Operational Amplifier & CRO

Op-amp block diagram, equivalent circuit & ideal characteristics

CRO functional blocks: deflection amplifier & CRT

These questions test deep theoretical understanding, mathematical derivations, and detailed electronic circuit analysis.