Question 1

How depletion layer is formed in diode?

Accepted Answer

The depletion layer is formed by the diffusion and recombination of holes and electrons across the PN junction, leaving immobile ions.

Question 2

Draw diode input output characteristic.

Accepted Answer

The V-I characteristic shows an exponential rise in forward bias after cut-in voltage, and a small leakage current in reverse bias until breakdown.

Question 3

Define concept of cascading in amplifiers.

Accepted Answer

Cascading is connecting multiple amplifier stages in series to achieve a higher total voltage gain.

Question 4

Differentiate frequency response of single stage and multistage amplifiers.

Accepted Answer

Multistage amplifiers have higher overall gain but a narrower frequency bandwidth compared to single-stage amplifiers.

Question 5

Explain Barkhausen criterion for oscillations.

Accepted Answer

Barkhausen criterion: loop gain magnitude = 1, and total loop phase shift = 0 or 360 degrees.

Question 6

What is the need of oscillator?

Accepted Answer

Oscillators are needed to generate continuous AC waveforms from a DC supply for clocking, communication, and signal processing.

Question 7

Why hysteresis is desirable in Schmitt trigger?

Accepted Answer

Hysteresis prevents noise-induced false triggering by creating two separate threshold voltage levels.

Question 8

Differentiate between integrator and differentiator.

Accepted Answer

Integrators output the integral of the input and act as low-pass filters; differentiators output the derivative and act as high-pass filters.

Question 9

What is the weighted register in DAC?

Accepted Answer

A Weighted Resistor DAC uses a network of resistors with binary-scaled values to convert digital bits into corresponding analog currents.

Question 10

Write the formulae of reference voltage in ADC.

Accepted Answer

The step resolution depends on the reference voltage and the number of bits: Step size = V_{ref} / (2^n).

Question 11

Perform the mathematical analysis of fixed biasing for NPN transistor.

Accepted Answer

Mathematical analysis of a Fixed Bias circuit using Kirchhoff's laws to find base and collector currents and collector-emitter voltage.

Question 12

Explain the operation of class A amplifier with calculation of power efficiency.

Accepted Answer

Class A amplifiers conduct for the full 360-degree cycle. Their maximum theoretical efficiency with a resistive load is 25%.

Question 13

Draw the circuit of astable multivibrator and explain its working.

Accepted Answer

An Astable Multivibrator is a free-running oscillator that continuously switches states using cross-coupled RC timing networks.

Question 14

Explain the summing amplifier in detail.

Accepted Answer

A summing amplifier uses an op-amp to linearly add multiple input voltages, often with programmable weights via input resistors.

Question 15

Discuss the parallel resonant band pass filter circuit.

Accepted Answer

A parallel resonant BPF uses an LC tank circuit that offers maximum impedance at the resonant frequency, allowing a narrow band of signals to pass.

Question 16

How D/A converter operates in bipolar range? Explain.

Accepted Answer

Bipolar operation in a DAC is achieved using Offset Binary coding and adding a fixed negative reference current to shift the output range.

Question 17

Discuss the principle of operation of differential amplifier.

Accepted Answer

A differential amplifier amplifies the difference between two inputs while rejecting noise common to both inputs.

Question 18

How the oscillations are maintained in Hartley oscillator? Also obtain the ex…

Accepted Answer

Hartley oscillator uses a tapped inductor for positive feedback. The frequency is determined by the LC tank circuit.

Question 19

What are the four possible topologies of a feedback amplifier? Explain with n…

Accepted Answer

The four topologies are Voltage-Series, Voltage-Shunt, Current-Series, and Current-Shunt, categorized by how they sample the output and mix with the input.

Question 20

Write a technical note on successive approximation analog to digital converte…

Accepted Answer

A Successive Approximation Register (SAR) ADC uses a binary search algorithm to quickly and efficiently convert analog signals to digital.

Question 21

Expplain the low frequency analysis of multistage amplifiers.

Accepted Answer

Low frequency analysis focuses on the effects of coupling and bypass capacitors, which introduce low-frequency poles and cause gain roll-off.

Question 22

For a class A amplifier, the maximum and minimum values of collector-emitter …

Accepted Answer

The overall efficiency of the Class A amplifier is calculated to be 33.3% based on the maximum and minimum voltage swings.

Analog Circuits