Question

Which one of the following represents the frequency response of a notch filter?

• A.
• B.
• C.
• D.

Hint:

When dealing with filters, remember: - A band-pass filter allows frequencies in a certain range to pass. - A notch filter attenuates a narrow band of frequencies while passing others.

Answer 1

The Correct Option is D

Step 1: Understanding the notch filter.
A notch filter is a type of band-stop filter that is designed to attenuate or reject a narrow band of frequencies while allowing the rest of the frequencies to pass through. This makes it useful for removing specific unwanted frequencies from a signal, such as electrical noise or interference.

Step 2: Frequency response characteristics.
The frequency response of a notch filter typically shows a sharp dip (attenuation) at the specific frequency that is being rejected. This dip corresponds to the center frequency of the notch filter, where the gain is minimized. Away from this center frequency, the gain increases and the filter allows signals to pass through with little attenuation.

Step 3: Comparing the options.
Option (A) represents a peak at the center frequency, which is characteristic of a band-pass filter, not a notch filter.
Option (B) shows a flat response with a sharp rise, which is characteristic of some low-pass or high-pass filters but not a notch filter.
Option (C) suggests a low gain at certain frequencies, but it does not accurately represent the sharp dip seen in a notch filter.
Option (D) correctly depicts a dip at a specific frequency, which is the defining characteristic of a notch filter's frequency response.

Correct Answer: (D) — a dip at a specific frequency.