EC-405 Analog Circuits - Dec 2024 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aExplain the concept of feedback and their types. Discuss amplifier with negative feedback and its advantages.
   How to answer

   • Define feedback concept
   • List types: positive and negative feedback
   • Explain amplifier with negative feedback with block diagram
   • Discuss advantages: stability, bandwidth, distortion reduction
2. 7 Marks
   bExplain various feedback topologies.
   How to answer

   • Define feedback topology concept
   • Explain series-shunt, shunt-series, series-series, shunt-shunt
   • Give block schematic for each
   • Mention input-output sampling effect
3. 7 Marks
   aDiscuss the concept of positive feedback. Explain the Barkhausen criterion.
   How to answer

   • Define positive feedback
   • Explain loop gain concept
   • State Barkhausen criterion magnitude and phase conditions
   • Explain role in oscillation
4. 7 Marks
   bDesign and explain the working of R.C. phase shift oscillator.
   How to answer

   • Show RC ladder network giving 180 degree shift
   • Explain amplifier plus feedback for total 360 degrees
   • Give circuit diagram of R.C. phase shift oscillator
   • Give frequency formula $f = 1/(2\pi RC\sqrt{6})$
5. 7 Marks
   aWhat do you mean by IC? What are the characteristics of IC's and give its advantages?
   How to answer

   • Define IC meaning integrated circuit
   • List characteristics: miniaturization, reliability, low cost
   • Explain advantages over discrete circuits
   • Give classification brief
6. 7 Marks
   bWhat do you understand by data sheets. Explain which type of information can be collected from data sheet.
   How to answer

   • Define data sheet purpose
   • List absolute maximum ratings, electrical characteristics
   • Explain pin details, thermal and package info
   • Explain how to extract design information
7. 7 Marks
   aDiscuss differential amplifier. Explain the advantages and applications of differential amplifier.
   How to answer

   • Define differential amplifier with circuit
   • Explain differential and common-mode operation
   • List advantages: high CMRR, noise rejection
   • Give applications in op-amp input stage, instrumentation
8. 7 Marks
   bDraw the equivalent circuit of ideal OP-amplifier. Also draw its pin diagram (IC-741) and explain functions of each pin.
   How to answer

   • Draw ideal op-amp equivalent circuit with Ri, AVD, Ro
   • Draw IC-741 8-pin DIP pin diagram
   • Label pins 1-8 functions
   • Explain offset null, supply, output functions
9. 7 Marks
   aExplain the following terms:

   1. i)CMRR
   2. ii)Slew Rate
   3. iii)PSRR
   How to answer

   • Define CMRR as Ad/Acm ratio
   • Define slew rate as max output voltage rate
   • Define PSRR as supply rejection ratio
   • Give formulas and units and significance
10. 7 Marks
    bWrite the essential ideal characteristics of OP-AMP.
    How to answer

    • List infinite gain, infinite input impedance
    • List zero output impedance, infinite bandwidth
    • List zero offset, infinite CMRR and slew rate
    • Explain ideal vs practical significance
11. 7 Marks
    aDiscuss the application of op-amp as integrator and differentiator circuit diagram.
    How to answer

    • Show integrator circuit with R input, C feedback and output formula
    • Show differentiator circuit with C input, R feedback
    • Explain working with waveforms
    • Mention applications and limitations
12. 7 Marks
    bDesign and explain the Butterworth 1st order low pass filter using OP-AMP.
    How to answer

    • Show first-order low-pass Butterworth circuit with RC and op-amp
    • Explain cutoff frequency design $f_H = 1/(2\pi RC)$
    • Explain gain setting and roll-off -20 dB/decade
    • Give frequency response explanation
13. 7 Marks
    aDraw the astable multi vibrator circuit diagram using IC-555 (timer IC) and explain its working.
    How to answer

    • Draw IC-555 astable circuit with RA, RB, C connections
    • Explain charging-discharging through threshold and trigger
    • Give frequency and duty cycle formulas
    • Explain output waveform
14. 7 Marks
    bExplain Schmitt trigger circuit with the help of neat and clean diagram.
    How to answer

    • Draw op-amp Schmitt trigger with positive feedback resistors
    • Explain upper and lower threshold voltages
    • Show hysteresis transfer characteristics
    • Mention noise immunity application
15. 14 Marks
    Write short note on any two:

    1. i)Fixed and Adjustable Voltage Regulator
    2. ii)Switching Regulator
    3. iii)Dual Power Supply
    How to answer

    • Select any two topics from list
    • Give circuit/working and features for each
    • Include diagram and applications
    • Conclude with uses