EX-305 Analog Electronics - 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
   aDraw the V-I characteristics of P-N junction diode. Also explain it's working with applications.
   How to answer

   • Define P-N junction and forward/reverse bias conditions
   • Sketch forward and reverse V-I characteristics with cut-in and breakdown regions
   • Explain working - diffusion/drift, depletion width variation
   • List applications - rectifiers, clippers, clampers
2. 7 Marks
   bExplain the half wave and full wave rectification using suitable diagram.
   How to answer

   • Show half-wave rectifier circuit with single diode and waveforms
   • Show full-wave centre-tap / bridge circuit with waveforms
   • Explain conduction in positive/negative half cycles
   • Compare output frequency, ripple and efficiency
3. 7 Marks
   aDescribe the working of zener diode with suitable circuit diagram. Also discuss its applications.
   How to answer

   • Define Zener diode and Zener breakdown
   • Draw reverse-bias regulator circuit
   • Explain working in breakdown region with voltage regulation
   • List applications - voltage regulator, reference, protection
4. 7 Marks
   bA P-N junction in series with $100\Omega$ resistor is forward biased so that a current of 100 mA flows. If the voltage across this combination is Instantaneously reversed to 10V at t = 0, determine the reverse current that flow through diode at t = 0.
   How to answer

   • State forward current 100 mA through 100 ohm resistor
   • Apply instantaneous reversal to 10V at t=0 with stored charge
   • Calculate initial reverse current as approximately -(V_reverse + V_forward_drop)/R
   • Obtain reverse current value at t=0
5. 7 Marks
   aCompare the NPN and PNP transistor circuits. Also explain the operating regions of BJT.
   How to answer

   • Draw NPN and PNP biasing with supply polarities
   • Compare current directions and voltage polarities
   • Define active, saturation, cut-off regions with junction bias
   • State operating condition for amplification and switching
6. 7 Marks
   bExplain the biasing techniques of BJT in brief.
   How to answer

   • Define need for biasing and Q-point
   • Briefly explain fixed bias, collector-to-base bias
   • Explain voltage-divider bias and its stability
   • Mention stability factor comparison
7. 7 Marks
   aDescribe feedback amplifier in brief. Explain the effect of negative feedback on amplifier gain.
   How to answer

   • Define feedback amplifier with block diagram
   • Distinguish positive and negative feedback
   • Derive gain with feedback $A_f = A/(1+A\beta)$
   • Explain gain reduction vs stability, bandwidth improvement
8. 7 Marks
   bExplain the class A and class B power amplifiers circuits.
   How to answer

   • Show class A bias at centre of load line with 360 deg conduction
   • Show class B bias at cut-off with 180 deg conduction
   • Explain circuits - single-ended vs push-pull
   • Compare efficiency, distortion and applications
9. 7 Marks
   aDraw the circuit diagram of astable multivibrator with waveform. Also explain its working.
   How to answer

   • Draw two-transistor astable multivibrator with RC coupling
   • Sketch complementary square waveforms at collectors
   • Explain alternate charging/discharging of capacitors
   • Give frequency formula $f = 1/(1.38RC)$
10. 7 Marks
    bDefine CMRR. Explain the differential amplifier with its use.
    How to answer

    • Define CMRR as $A_d/A_c$ ratio
    • Draw differential amplifier with dual inputs
    • Explain differential vs common-mode operation
    • State uses - Op-Amp input stage, noise rejection
11. 7 Marks
    aDescribe the characteristics of an ideal Op-Amp. Also give the applications of Op-Amp circuit.
    How to answer

    • List ideal Op-Amp parameters - infinite gain, impedance, zero offset
    • Explain virtual short and characteristics table
    • Draw basic Op-Amp symbol with inputs
    • List applications - adder, subtractor, integrator
12. 7 Marks
    bExplain the log and antilog amplifier with suitable diagram.
    How to answer

    • Draw Op-Amp with diode in feedback for log amp
    • Give output relation $V_o = -K \log V_i$
    • Draw antilog with diode at input
    • State conditions and applications in multiplication
13. 7 Marks
    aDraw and explain the inverting and non-inverting modes of Op-Amp.
    How to answer

    • Draw inverting amplifier with input resistor and feedback
    • Give gain $A = -R_f/R_1$
    • Draw non-inverting amplifier with voltage divider
    • Give gain $A = 1+R_f/R_1$ and working
14. 7 Marks
    bExplain 555 timer circuit with its applications.
    How to answer

    • Draw 555 timer block with comparators, flip-flop, discharge transistor
    • Explain pin functions and astable/monostable operation
    • Give timing waveforms and frequency formula
    • List applications - timers, oscillators, PWM
15. 14 Marks
    Write short notes on:

    1. a)MOSFET
    2. b)Schottky diode
    3. c)Hartley-Colpitts oscillator
    4. d)Schmitt trigger
    How to answer

    • MOSFET: structure, types, working and characteristics
    • Schottky diode: metal-semiconductor junction, fast switching
    • Hartley-Colpitts: LC oscillator circuits and frequency formula
    • Schmitt trigger: hysteresis, UTP/LTP and waveform shaping