(SEM IV) THEORY EXAMINATION 2023-24 ANALOG CIRCUITS

This document is a B.Tech (Semester IV) Theory Examination Question Paper for the subject BEC402 – Analog Circuits, from the academic year 2023–2024.
It is a 3-hour, 70-mark examination designed to evaluate a student’s understanding of amplifier circuits, feedback concepts, oscillators, operational amplifier applications, differential amplifiers, and frequency response analysis.

The exam is divided into three sections—A, B, and C—covering short conceptual questions, calculation/derivation-based questions, and advanced circuit analysis/oscillator design questions.

SECTION A – Short Answer Questions (14 Marks)

Seven short questions (2 marks each) test basic concepts of analog electronics:

Definition & characteristics of a voltage amplifier

Method of estimating voltage gain

Effect of feedback on amplifier gain

Basic concept of an oscillator

Maximum usable load in a current mirror

Definition of CMRR (Common Mode Rejection Ratio)

Definition of Class A amplifier operation

These questions test foundational knowledge of amplifiers, feedback, and analog parameters.

SECTION B – Intermediate Circuit Concepts (21 Marks)

Students must attempt any three of the following:

Circuit model of a current amplifier

Calculations for voltage-series feedback amplifier:

Voltage gain

Input resistance

Output resistance
(Given: Av = 300, Ri = 1.5 kΩ, Ro = 50 kΩ, β = 1/15)

Detailed discussion of Barkhausen Criterion for oscillations

Concept, structure, and operation principle of a Differential Amplifier

Working principle + derivation of output voltage of an Op-Amp Integrator

This section checks applied understanding, formulas, and block-level circuit behavior.

SECTION C – Long Answer / Advanced Analytical Questions (28 Marks)

Each question contains two sub-parts; students must attempt one from each.

3. Amplifiers & BJT Concepts

Trans-resistance amplifier (detailed explanation)

Small-signal operation of BJT

4. Frequency Response & Stability

Frequency response of Common Emitter (CE) configuration

Impact of phase margin & gain margin on system stability

5. Oscillator Design

Working & frequency calculation of Wien Bridge Oscillator

Given: R1 = R2 = 200 kΩ, C1 = C2 = 200 pF

Construction & working of Hartley Oscillator, including inductive feedback

6. Differential Amplifiers & Op-Amp Compensation

Concept & significance of ICMR (Input Common Mode Range)

Compensation techniques in op-amp design and their impact on stability

7. Op-Amp Applications & Amplifier Classes

Design & application of Summing Amplifier

Explanation of Class B amplifier operation

This section evaluates deep understanding required in practical analog circuit design.

Overall Purpose of the Document

This exam paper evaluates a student's comprehensive understanding of:

Voltage, current, differential, and op-amp amplifiers

Feedback topologies and their influence on circuit performance

Oscillator design principles and Barkhausen criterion

Small-signal analysis of BJT

Frequency response & stability of analog circuits

Compensation methods in op-amp design

Class A & Class B amplifier operations

It integrates calculations, diagrams, conceptual theory, and analytical reasoning.