Question

The shape factor of an anti-aliasing filter is given by the ratio of the frequency at ___ dB attenuation point to the frequency at ___ dB point.

(a) 80, 3

(b) 3, 80

(c) -80, -3

(d) -3, -80

The question was asked during an interview.

My doubt is from ADC Tradeoffs in chapter Technology Tradeoffs in Software Defined Radio of Cognitive Radio

Answer 1

The correct answer is:

(d) -3, -80

The shape factor of an anti-aliasing filter is given by the ratio of the frequency at the -3 dB attenuation point to the frequency at the -80 dB attenuation point. This ratio helps characterize the filter's sharpness or how effectively it attenuates unwanted frequencies, which is crucial for preventing aliasing in the signal conversion process.