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.
