Definition check: Band-stop (notch) filter passband and stopband Does a band-stop filter pass the frequencies within its lower and upper critical frequencies and reject all others, or is it the opposite?

Introduction / Context:
Filter terminology distinguishes which frequency regions are passed and which are rejected. Confusing band-pass with band-stop leads to design and analysis errors when specifying cutoffs and Q.

Given Data / Assumptions:

• Lower critical frequency fL and upper critical frequency fH define the edges of a band.
• Magnitude at critical frequencies is commonly taken at the −3 dB point for first-order sections or appropriately defined for higher order.
• Band-stop (notch) filters reject a band; band-pass filters pass a band.

Concept / Approach:

A band-stop filter attenuates frequencies between fL and fH (the stopband) and passes frequencies below fL and above fH (the passbands). Conversely, a band-pass filter passes frequencies between fL and fH and rejects those well below or above.

Step-by-Step Solution:

Verification / Alternative check:

Examine prototype transfer functions: a parallel RLC in series yields a notch at resonance, attenuating frequencies near f0 between fL and fH; outside that band, the response recovers—classic band-stop behavior.

Why Other Options Are Wrong:

• Any version of “True” reverses the definitions.
• Active vs passive or narrow vs wide notch does not flip pass/stop meanings.

Common Pitfalls:

Swapping the roles of band-pass and band-stop because both use two critical frequencies. Always anchor on whether the middle band is passed (band-pass) or rejected (band-stop).

Final Answer:

False