(SEM IV) THEORY EXAMINATION 2024-25 ANALOG ELECTRONICS CIRCUITS

The uploaded document is the complete B.Tech Semester IV Theory Examination Paper (2024–25) for the subject BOE408 – Analog Electronics Circuits. This official exam paper is designed to thoroughly evaluate a student’s understanding of analog electronic components, amplifier behavior, oscillator circuits, op-amp applications, and frequency-domain responses. The exam carries a total of 70 marks and the duration is 3 hours, as mentioned on the top of Page 1. The entire paper is presented in a bilingual format—English and Hindi—ensuring accessibility for students from diverse academic backgrounds.
 

The first section of the paper, Section A, contains seven compulsory short-answer questions worth 2 marks each. These questions focus on testing the student’s foundational knowledge of analog circuits. Topics include defining a voltage amplifier and stating its ideal characteristics, explaining the concepts of transconductance and trans-resistance amplifiers, and understanding the significance of the Miller effect in high-frequency amplifiers. The section also asks about voltage shunt feedback topology, Barkhausen criterion for sustained oscillations, the importance of Input Common Mode Range (ICMR), and a simple numerical problem involving the gain of an inverting operational amplifier. This section evaluates quick conceptual clarity and the student’s ability to recall essential definitions, formulas, and principles.

In Section B, the exam transitions into deeper descriptive questions. Students are required to attempt any three out of five questions, each carrying 7 marks, thereby testing their analytical thinking and explanatory ability. The questions in this part demand detailed explanations and, in some cases, circuit diagrams. Students are asked to draw the hybrid-π small-signal model of a BJT and explain its components, analyze and compare the operation and frequency response of cascode and cascade amplifiers, and deeply discuss the construction and functioning of the Hartley oscillator—including deriving its oscillation frequency. Further questions explore the differential amplifier, including its classifications, operations, and mathematical expressions for differential gain and common-mode gain. The section also contains a question requiring the drawing and full explanation of an op-amp-based Schmitt Trigger circuit, including hysteresis behavior and real-world applications. This section evaluates how well a student understands internal behaviors of analog circuits and their mathematical analysis.

The third part, Section C, contains long-answer analytical questions divided into multiple sub-parts (Q3 to Q7). In each sub-part, the student must choose and attempt one question. These questions demand derivations, in-depth mathematical treatment, and detailed reasoning. Topics include deriving expressions for voltage gain, input resistance, and output resistance for a Common-Source (CS) amplifier using small-signal models, and determining DC operating points (such as IB and Vc) for a given BJT circuit diagram. Further questions deal with feedback amplifiers—specifically calculating the new gain, input resistance, and output resistance when negative feedback is applied. Additional technical topics include differentiating between Class A, B, AB, and C amplifiers based on conduction angle and efficiency.

The later portions of Section C focus intensively on oscillator circuits, asking students to draw and explain RC phase shift oscillators and derive the condition and frequency of oscillation. Another option involves the Clapp oscillator, requiring an explanation of its working, a derivation of oscillation frequency, and a comparison of its frequency stability with the Colpitts oscillator. The exam also touches on advanced analog design topics such as current mirrors, where students must define the minimum sustainable voltage VON, describe how it is determined, and draw various topologies while explaining their differences and advantages. One of the final questions involves op-amp based active filters, including the procedure for designing such filters and calculating the upper and lower cut-off frequencies of a provided band-pass filter circuit. The concluding question asks students to derive the expressions for op-amp-based integrator and differentiator circuits using suitable diagrams.

Overall, this question paper provides a comprehensive evaluation of all major analog electronics topics, spanning small-signal analysis, amplifier configurations, feedback theory, oscillator design, op-amp applications, and frequency-domain behaviors. The structure and layout of the paper ensure that both conceptual understanding and problem-solving skills are rigorously tested. With its bilingual formatting and balanced distribution of short, medium, and long questions, this document serves as a complete and well-structured examination tool for assessing a student’s academic mastery of Analog Electronics Circuits.