Which filter type passes certain middle-frequency bands while attenuating high and low frequencies using resonant circuits?

Which filter type passes certain middle-frequency bands while attenuating high and low frequencies using resonant circuits?

• A. Ripple amplitude
• B. Cutoff Frequency
• C. Band-reject
• D. Band-pass

Answer: (D)

Band-pass filters are designed to let through a limited range of frequencies centered around a chosen frequency while attenuating frequencies above and below that range. When built with resonant LC circuits, you set a center frequency where the circuit resonates. At that frequency, the impedance of the series resonance becomes very low, so the signal passes with minimal loss, creating the pass band. As you move away from the center frequency, the impedance rises and the signal is increasingly attenuated, giving a defined bandwidth. A higher quality factor makes the pass band narrower. This matches the description of passing middle-frequency bands using resonance. The other terms describe different behaviors: a band-reject filter attenuates the middle band instead of passing it, a cutoff frequency is simply where attenuation starts and doesn’t specify a pass band, and ripple amplitude refers to variation within the pass band, not which frequencies are passed.

Band-pass filters are designed to let through a limited range of frequencies centered around a chosen frequency while attenuating frequencies above and below that range. When built with resonant LC circuits, you set a center frequency where the circuit resonates. At that frequency, the impedance of the series resonance becomes very low, so the signal passes with minimal loss, creating the pass band. As you move away from the center frequency, the impedance rises and the signal is increasingly attenuated, giving a defined bandwidth. A higher quality factor makes the pass band narrower. This matches the description of passing middle-frequency bands using resonance. The other terms describe different behaviors: a band-reject filter attenuates the middle band instead of passing it, a cutoff frequency is simply where attenuation starts and doesn’t specify a pass band, and ripple amplitude refers to variation within the pass band, not which frequencies are passed.