Question
Which filter type has ripple in the passband and a sharp cutoff?
Answer Options
- A) A Butterworth filter
- B) An active LC filter
- C) A passive op-amp filter
- D) A Chebyshev filter
Correct Answer: D
Explanation
Filter design involves trading off a smooth response in the desired passband against the sharpness (steepness) of the transition to the stopband. The Butterworth filter is known for its maximally flat passband (no ripple), but its cutoff slope is relatively gradual.
The Chebyshev filter achieves a much sharper and faster cutoff rate (better selectivity) than the Butterworth filter for the same number of components. The trade-off required to achieve this sharpness is that the Chebyshev filter exhibits unavoidable variations in amplitude, or ripple in the passband. This filter type is often preferred in communications receivers where maximum selectivity against adjacent channel interference is more important than perfect flatness.
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