UPSC ESE E&T Electronics Engineering Syllabus

Electronics Engineering syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Electronics Engineering in UPSC ESE E&T, not a summary of it.

1. 1

   Basic Electronics Engineering

   5 topics

   • Diodes
   • Transistors
   • Operational Amplifiers
   • Oscillators
   • Voltage Regulators
2. 2

   Digital Electronics

   6 topics

   • Number Systems
   • Logic Gates
   • Flip-Flops
   • Counters
   • Shift Registers
   • Microprocessors and Microcontrollers
3. 3

   Analog Electronics

   4 topics

   • Small Signal Analysis
   • Large Signal Analysis
   • Feedback Amplifiers
   • Power Amplifiers

Electronics Engineering flashcards for UPSC ESE E&T

24 of 51 cards from the Electronics Engineering deck — real questions with worked answers.

1. What is the threshold (cut-in) voltage for a silicon and a germanium PN-junction diode?

   Silicon ≈ 0.7 V; Germanium ≈ 0.3 V. Below this forward voltage the diode conducts negligibly.

2. State the Shockley diode equation relating diode current to applied voltage.

   I = I_S (e^(V/(ηV_T)) − 1), where I_S is reverse saturation current, η is the ideality factor (1–2), and V_T = kT/q ≈ 26 mV at room temperature.

3. How does a Zener diode operate and what is its main application?

   It is operated in reverse breakdown, where voltage stays nearly constant despite current changes. Main use: voltage regulation/reference.

4. Differentiate Zener breakdown from Avalanche breakdown in diodes.

   Zener breakdown occurs in heavily doped junctions at low voltage (<5–6 V) due to strong field tunneling and has a negative temperature coefficient. Avalanche occurs in lightly doped junctions at higher voltage via carrier multiplication (impact ionization) and has a positive temperature coefficient.

5. For a full-wave bridge rectifier with sinusoidal input, give the ripple factor and rectification efficiency.

   Ripple factor ≈ 0.48; maximum rectification efficiency ≈ 81.2%. (Half-wave: ripple factor 1.21, efficiency 40.6%.)

6. In a full-wave center-tapped rectifier, what is the Peak Inverse Voltage (PIV) across each diode?

   PIV = 2V_m (twice the peak of one half of the secondary), whereas in a bridge rectifier PIV = V_m.

7. What are the three operating regions of a BJT and the junction bias conditions for each?

   Active: emitter junction forward-biased, collector junction reverse-biased. Saturation: both junctions forward-biased. Cutoff: both junctions reverse-biased.

8. Define the BJT current gains α and β and give the relationship between them.

   α = I_C/I_E (common-base gain, <1); β = I_C/I_B (common-emitter gain). Relationship: β = α/(1−α) and α = β/(1+β).

9. Compare the three BJT amplifier configurations (CE, CB, CC) in terms of gain and impedance.

   CE: high voltage & current gain, medium input/output impedance, 180° phase shift. CB: high voltage gain, current gain <1, low input/high output impedance. CC (emitter follower): voltage gain ≈1, high current gain, high input/low output impedance — used for buffering.

10. What distinguishes a JFET, a depletion-MOSFET, and an enhancement-MOSFET?

    JFET: always normally-ON, controlled by reverse-biased gate. Depletion MOSFET: normally-ON, works in both depletion and enhancement. Enhancement MOSFET: normally-OFF, conducts only when |V_GS| exceeds threshold V_T.

11. Write the MOSFET drain current equation in saturation (active) region.

    I_D = (1/2) μ_n C_ox (W/L)(V_GS − V_T)^2 (1 + λ V_DS), often written I_D = K(V_GS − V_T)^2.

12. List the ideal characteristics of an operational amplifier.

    Infinite open-loop gain, infinite input impedance, zero output impedance, infinite bandwidth, infinite CMRR, zero offset voltage, and zero input bias current.

13. What are the two 'golden rules' of an ideal op-amp in negative feedback?

    1) No current flows into either input terminal (infinite input impedance). 2) The voltage difference between the two inputs is zero — the 'virtual short' (V+ = V−).

14. Give the closed-loop gain of an inverting and a non-inverting op-amp amplifier.

    Inverting: A = −R_f/R_1. Non-inverting: A = 1 + R_f/R_1.

15. Define CMRR for an op-amp and give its expression.

    Common-Mode Rejection Ratio = ratio of differential gain to common-mode gain: CMRR = A_d/A_cm, usually expressed in dB as 20 log10(A_d/A_cm). Higher is better.

16. What is the slew rate of an op-amp and how does it limit performance?

    Slew rate = maximum rate of change of output voltage (V/µs), SR = dV_out/dt|max. It limits the maximum frequency for a given output amplitude (full-power bandwidth f = SR/(2πV_peak)).

17. State the Barkhausen criterion for sustained oscillations.

    Loop gain magnitude |Aβ| = 1 and total phase shift around the loop = 0° (or 360°). Together they sustain oscillations at the desired frequency.

18. Give the frequency of oscillation for a Wien-bridge oscillator (equal R and C).

    f = 1/(2πRC), with the amplifier gain set to ≥3 to satisfy Barkhausen criterion.

19. Give the frequency of oscillation and gain condition for an RC phase-shift oscillator.

    f = 1/(2πRC√6); the amplifier must provide a gain of at least 29 to overcome the feedback network attenuation.

20. Give the oscillation frequency for Hartley and Colpitts LC oscillators.

    Both: f = 1/(2π√(LC_eq)). Hartley uses tapped inductors (L = L1+L2+2M), Colpitts uses series capacitors (C = C1C2/(C1+C2)).

21. For a Zener shunt voltage regulator, what condition keeps the Zener in regulation?

    The Zener current must remain between I_Z(min) and I_Z(max) for all input voltage and load current variations; load voltage stays at V_Z.

22. Define line regulation and load regulation of a voltage regulator.

    Line regulation = change in output voltage per unit change in input voltage (ΔV_out/ΔV_in). Load regulation = change in output voltage per unit change in load current (ΔV_out/ΔI_load). Lower values mean better regulation.

23. How does a series-pass linear regulator differ from a switching regulator in efficiency?

    Linear (series-pass) regulators dissipate excess voltage as heat → low efficiency (~30–60%). Switching regulators rapidly switch a transistor and use LC filtering → high efficiency (~80–95%).

24. Convert the binary number 1011 to decimal.

    1011₂ = 8 + 0 + 2 + 1 = 11₁₀.

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