Which parameter defines notch depth and sharpness in an active notch filter?

Which parameter defines notch depth and sharpness in an active notch filter?

• A. Center frequency fc
• B. Quality factor Q
• C. Gain
• D. Load impedance

Answer: (B)

The parameter that sets how deep and how narrow the notch is in an active notch filter is the quality factor, Q. Q measures how selective the circuit is around the notch frequency: Q = f0 divided by the notch’s bandwidth. A higher Q means a narrower notch and a deeper dip, because the filter cancels signals more strongly very close to the notch frequency and the response recovers more quickly away from it. The center frequency simply specifies where the notch occurs, not how sharp or deep it is. Load impedance affects termination and overall matching, and the stage gain mainly influences overall levels rather than the intrinsic sharpness of the notch. So, Q is the key parameter controlling both notch depth and sharpness.

The parameter that sets how deep and how narrow the notch is in an active notch filter is the quality factor, Q. Q measures how selective the circuit is around the notch frequency: Q = f0 divided by the notch’s bandwidth. A higher Q means a narrower notch and a deeper dip, because the filter cancels signals more strongly very close to the notch frequency and the response recovers more quickly away from it. The center frequency simply specifies where the notch occurs, not how sharp or deep it is. Load impedance affects termination and overall matching, and the stage gain mainly influences overall levels rather than the intrinsic sharpness of the notch. So, Q is the key parameter controlling both notch depth and sharpness.