Question

At 3dB cut-off frequencies power will be __________

(a) Half of maximum value

(b) Quarter of maximum value

(c) 70.7% of maximum value

(d) Same as maximum value

This question was posed to me in final exam.

The question is from General Frequency Consideration topic in section Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

The correct option is (a) Half of maximum value

The best explanation: 3dB cut-off frequency is the frequency at which the power becomes half of its maximum value. That is the voltage gain becomes 0.707 times maximum voltage gain. The importance of 3dB points is that for a human ear, it will not notice the fall in power of the signal up to 50% of maximum power.