Noise in Analog Circuits MCQs

Practice Noise in Analog Circuits MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Analog ElectronicsNoise in Analog Circuits

The noise spectral density associated with flicker noise generally becomes more significant as frequency?

ADecreases
BIncreases without limit
CRemains exactly constant at all frequencies
DEquals the supply frequency only

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Correct Answer: A. Decreases

Explanation: Flicker noise is commonly called 1/f noise because its spectral density increases toward lower frequencies.

Reference: Standard analog electronics: flicker noise

Question 2

Analog ElectronicsNoise in Analog Circuits

Ideal white noise has approximately what power spectral density over the frequency range where it is considered white?

AConstant
BProportional to 1/f
CZero at every frequency
DA single spectral line

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Correct Answer: A. Constant

Explanation: White noise is modeled as having approximately flat power spectral density over the frequency band of interest.

Reference: Standard analog electronics: white noise

Question 3

Analog ElectronicsNoise in Analog Circuits

The thermal-noise mean-square voltage of a resistor over bandwidth B is proportional to?

A4kTRB
B4kT/(RB)
CR/(4kTB)
DB/(4kTR)

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Correct Answer: A. 4kTRB

Explanation: The standard resistor thermal-noise relation is mean-square voltage vn^2=4kTRB.

Reference: Standard analog electronics: resistor thermal noise

Question 4

Analog ElectronicsNoise in Analog Circuits

If the measurement bandwidth for white voltage noise is increased by a factor of 4, the RMS noise voltage increases approximately by a factor of?

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Correct Answer: A. 2

Explanation: Mean-square white noise is proportional to bandwidth, so RMS noise is proportional to sqrt(B). Increasing B fourfold doubles RMS noise.

Reference: Standard analog electronics: noise bandwidth numerical

Question 5

Analog ElectronicsNoise in Analog Circuits

Noise figure of an amplifier quantifies degradation of?

ASignal-to-noise ratio from input to output
BDC voltage gain only
CTransistor beta only
DOscillation frequency only

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Correct Answer: A. Signal-to-noise ratio from input to output

Explanation: Noise figure compares input and output SNR and indicates how much additional noise the amplifier effectively contributes.

Reference: Standard analog electronics: noise figure

Question 6

Analog ElectronicsNoise in Analog Circuits

An amplifier has an input SNR of 40 dB and output SNR of 34 dB. Its noise figure is approximately?

A3 dB
B6 dB
C34 dB
D74 dB

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Correct Answer: B. 6 dB

Explanation: Noise figure in decibels is SNRin(dB)-SNRout(dB)=40-34=6 dB.

Reference: Standard analog electronics: noise figure numerical