In a push-pull amplifier configuration, what is the phase relationship between the two transistor inputs?

The correct answer is A: 180° out of phase. Push-pull amplifiers use complementary transistors driven 180° out of phase to handle positive and negative half-cycles separately.

The Miller effect in a Common Emitter amplifier results in:

The correct answer is C: Both A and B. Miller effect causes effective input capacitance to increase by factor (1 + |Av|), reducing input impedance and bandwidth. This limits high-frequency response.

In a log amplifier circuit, what is the primary source of error in practical implementations?

The correct answer is B: Reverse saturation current variation with temperature. Log amplifier uses diode in feedback. Temperature changes cause Is (reverse saturation current) to vary exponentially, directly affecting the logarithmic transfer function. This is the dominant non-ideal effect.

In a MESFET (Metal-Semiconductor FET), compared to MOSFET:

The correct answer is D: All of the above are correct. MESFETs use Schottky metal-semiconductor junctions instead of oxide layers, resulting in lower gate capacitance, better high-frequency response (f_T/f_max higher), and simpler manufacturing process, especially in GaAs technology.

An inverting amplifier using op-amp has Rf = 100 kΩ and Rin = 10 kΩ. What is the voltage gain magnitude?

The correct answer is A: -10. For inverting amplifier, Gain = -Rf/Rin = -100k/10k = -10. The negative sign indicates 180° phase shift.

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Electronics (ECE)
Signals & Systems

Analog/digital electronics, communication

34 Q 4 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–34 of 34

Topics in Electronics (ECE)

All Electronic Devices 100 Digital Electronics 100 Analog Circuits 100 Signals & Systems 100

Q.31 Easy Signals & Systems

Nyquist sampling rate for a signal with maximum frequency 5 kHz is:

A 2.5 kHz

B 5 kHz

C 10 kHz

D 20 kHz

Correct Answer: C. 10 kHz

EXPLANATION

Nyquist sampling rate = 2 × (maximum frequency) = 2 × 5 = 10 kHz

Test

Q.32 Easy Signals & Systems

The Z-transform of x[n] = aⁿu[n] is:

A z/(z-a)

B 1/(z-a)

C z/(z+a)

D a/(z-1)

Correct Answer: A. z/(z-a)

EXPLANATION

Z-transform: X(z) = ∑aⁿu[n]z⁻ⁿ = z/(z-a) for |z| > |a|

Test

Q.33 Easy Signals & Systems

Which of the following is a causal system?

A y[n] = x[n+1] + x[n]

B y[n] = x[n] + x[n-1]

C y[n] = x[-n]

D y[n] = x[n] + x[n+2]

Correct Answer: B. y[n] = x[n] + x[n-1]

EXPLANATION

A causal system does not depend on future values. Only option B satisfies this condition.

Test

Q.34 Easy Signals & Systems

A continuous-time signal x(t) = 5cos(2πt + π/4) has a fundamental frequency of:

A 1 Hz

B 2 Hz

C 0.5 Hz

D 4 Hz

Correct Answer: A. 1 Hz

EXPLANATION

From x(t) = 5cos(2πt + π/4), ω = 2π, so f = ω/2π = 1 Hz

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Electronics (ECE) Signals & Systems

Electronics (ECE)
Signals & Systems