Question

Which of the following is true about the cut-off frequency ωB of a first-order low-pass filter? Suppose that the DC gain is 1.
a.When the input is a sinusoid operating at ωB, the output is phase shifted from the input phase by −45∘.
b.The Bode magnitude plot rolls off by −40dB/decade after the corner frequency, at ωB.
c.When the input is a sinusoid operating at ωB, the output amplitude is scaled by a factor of 0.707≈−3dB.
d.Inputs operating at frequencies far below ωB are weakly attenuated (i.e. the amplitudes of outputs are approximately equal to the amplitudes of inputs.)
e.Inputs operating at frequencies far above ωB have phase shifts of close to −90∘.

Answer 1

c, d are obviously true
b. Bode rolls off at 20db/decade on simple RC filterss
think about a, e.

Answer 2

c,d