ESE EC : Analog Circuits - National Champion Test for ESE & GATE EC Exams

Question 1

Match List- I (Electronic Circuit) with List- II (Characteristic) and select the correct answer using the code given below the lists.
List I
A) CE
B) CB
C) CC
D) Darlington pair
List II
1) The circuit introduces a phase inversion of 180⁰.
2) The circuit is rarely used.
3) The name, emitter follower is also used for the circuit
4) The circuit consists of two circuits connected in cascade.

Question 2

For BJT, early voltage V_A is 100 V. in common emitter configuration, quiescent V_CE is 10 V. What percentage change in quiescent I_C would occur, if early voltage V_A is made ∞?

Question 3

The maximum power dissipation capacity of a transistor is 50 mW. If the collector emitter voltage is 10 V, what is the safe collector current that can be allowed through the transistor?

Question 4

Consider the following statements about a good power supply.
1) The a.c. ripple should be high.
2) S_V, (voltage stability factor) should be low.
3) S_T, (Temperature stability factor) should be low.
Which of the above statements are correct?

Question 5

Assertion (A): A rectifier with inductor filter is more efficient for high load current.
Reason (R): In rectifier with inductor filter we can use a larger choke to reduce ripple, larger choke will have higher dc resistance which will result in lower dc output voltage for higher load current.

Question 6

An amplifier has an open loop gain of 1000 ± 10. Negative feedback is provide such that the gain variation remains within 0.1%. What is the amount of feedback β_F?

Question 7

A feedback amplifier has an open loop gain of –100 if 4% of the output is fed back in a degenerative loop, what is the closed loop gain of the amplifier?

Question 8

A negative-feedback closed-loop system is supplied to an input of V. The system has a forward gain of 1 and a feedback gain of 1. What is the output voltage?. Assume input voltage is 5 V.

Question 9

The drain gate capacitance of a junction FET is 2pE. Assuming a common source voltage gain of 20, what is the input capacitance due to miller effect?

Question 10

For the circuit shown below if g_m = 3×10^–3 and R_S= 3000Ω then what is the value of R₀?

Question 11

Which one of the following gain equations is correct for a MOSFET common-source amplifier? (g_m is mutual conductance, and RD is load resistance at the drain).

Question 12

A transistor RC coupled amplifier is designed for a voltage and band gain of 20. But a measurement at a particular frequency shows the gain to be only 14. What is the likely phase shift at this frequency ?
(consider low frequency analysis)

Question 13

f_T is the frequency at which the short circuit.

Question 14

A cascaded amplifier comprises N identical non-interacting stages, each having a lower 3 dB frequency of f_L. If f_L* is the lower 3 dB frequency of the cascaded amplifier, then which one of the following is correct?

Question 15

Consider the following statements.
_{1) To achieve wide bandwidth, a transistor was a small C}^b,c is chose.
_{2) To achieve wide bandwidth, a transistor with a small C}^b,e is chosen.
_{3) To achieve wide bandwidth, a transistor with a small base spreading resistance is chosen. Which of the statements given above are correct.}

Question 16

Consider the following statements:
1) A Schmitt trigger circuit can be emitter- coupled bi-stable circuit.
2) Schmitt trigger circuit exhibits hysteresis phenomenon.
3) The output of a Schmitt trigger will be triangular if the input is a square wave.
Which of these statements are correct?

Question 17

The frequency of oscillation of a stable multi-vibrator with component values R₁ = 2kΩ, R₂ = 20kΩ, C₁ = 0.01 μF and C₂ = 0.05 μF is

Question 18

The figure given below shows the circuit of which one of the following?

Question 19

If the inverting input terminal of an operational amplifier is grounded and a sinusoidal voltage waveform is applied at the nono- inverting input terminal, the output will be

Question 20

A differential amplifier has input V₁ = 1050 μV and V₂ = 950μV with CMRR = 1000. What is the error in the differential output?

Question 21

An I.C. operational amplifier has a typical open loop gain of 1200 and the common mode rejection of 55dB. What is the common mode rejection ratio (CMRR)?

Question 22

Three amplifier each of gain (A₀/2) and producing a phase of 60 ° are connected in tandem. The feedback loop is closed through a positive gain of 0.008. what should be the value of A₀ for the system to be oscillatory?

Question 23

Consider the following statements related to a shunt generator:
1) The full load voltage is lower than no load voltage.
2) The above lowering is partly due to voltage drop in armature resistance.
3) The field current does not change with load and has no effect on generated voltage.
Which of the following statements given above are correct?

Question 24

Assertion (A): All practical R-C phase shift oscillator generate sinusoidal oscillation with some amount of amplitude distortion, which cannot be avoided.
Reason (R): The amplitude distortion of a sinusoidal oscillator is controlled by the onset of non-linearity by the amplifying device.

Question 25

Which one of the following oscillators is well suited for the generation of wide range of audio-frequency sine waves?

Question 26

Assertion (A): The frequency stability of an oscillator improves as

increases, where θ refers to the phase angle of the loop gain.
Reason (R): For sustained oscillation occur in an oscillator circuit, the loop shift should to 0 ° or

where n is an integer.

Question 27

For an OP-Amp phase shift oscillation, the frequency of oscillations is

Question 28

Consider the following statements: regarding a common emitter amplifier. It can be converted into an oscillator by
1) Providing adequate positive feedback.
2) Phase shifting the output by 180 ° and feeding this phase-shifted output to the input.
3) Using only a series tuned circuit as a load on the amplifier.
4) Using the negative resistance device as a load on the amplifier.

Question 29

Which of the following is the principal factor that contributes to the doubling of the conversion efficiency in a transformer coupled amplifier?

Question 30

A power amplifier with a gain of 100 has an output of 12 V at 1.5 kHz along with a second harmonic content of 25 percent. A negative feedback is to be provided to reduce the harmonic content of the output to 2.5 percent. What should be the gain of the feedback path and the level of signal input to the overall system, respectively?