Latest ELECTRONICS Aptitude Question SOLUTION: What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?

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What do you mean by 3 dB cutoff
frequency? Why is it 3 dB, not 1 dB?

Asked In ELECTRONICS (10 years ago)

Unsolved Read Solution (4)

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Read Solution (4) :

raghu  (10 years ago)

10*log(1/2)=-3
-3db point is the power where the signal power is exactly half the maximum.
and 3db is considered because it is a practical observation that the required signal characteristics of the signal can be obtained till the power is half the maximum or the amplitude is 0.707 times the maximum amplitude.
one more : our human year cannot sense the changes in the audio from maximum power to half power or -3db power. so there is a chance that the device can be operated in the range where the power is greater than or equal to -3db power.

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mohini  (10 years ago)

to find the bandwidth of the filter we generally consider the frequencies over which the gain of filter is greater than 0.5(of course the maximum gain is 1 i.e 10log 1 =0dB).
but the same if we consider 1dB it means gain is 0.1 and that is too less as these frequency components are highly attenuated.
but rather many definition of bandwidths are used .

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sachin patel  (10 years ago)

the frequency at which signal magnetude decrease below .707 of its maximum value called 3 db frequency

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SHAHEEN  (9 years ago)

3 db is the exactly half freq so we always consider it

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