Active filter identification (op-amp based): A single-op-amp multiple-feedback network using both an input capacitor and a feedback capacitor is commonly used to realize a band-pass response with a center frequency f0 and two cutoffs fL and fH. Based on this standard topology, is the identification “band-pass filter” appropriate?

Introduction / Context:
Active filters built around operational amplifiers implement selective frequency responses without inductors. A widely used configuration is the multiple-feedback (MFB) band-pass filter, which uses two capacitors and two resistors around a single op-amp to produce a peak at a chosen center frequency f0 and attenuation at frequencies far below and far above f0.

Given Data / Assumptions:

• Standard single-op-amp MFB topology with one capacitor in the input path and another in the feedback path.
• Linear operation (no clipping), proper biasing, and stable negative feedback.
• Defined lower and upper −3 dB corner frequencies fL and fH around a center f0.

Concept / Approach:
A band-pass filter is defined by a pass region centered at f0 with attenuation below fL and above fH. The MFB design equations set f0, quality factor Q, and midband gain based on the component values. Because the transfer magnitude rises toward f0 and falls away on both sides, the correct classification of this standard op-amp network is “band-pass.”

Step-by-Step Solution:

Verification / Alternative check:
Simulated Bode plots of the MFB filter show a clear midband pass region with slope transitions of approximately +20 dB/dec and −20 dB/dec near the edges for a second-order realization.

Why Other Options Are Wrong:
Incorrect: contradicts the well-known function of the MFB network.
Q = 0.5 only: Q controls selectivity; the response remains band-pass for a wide range of Q values.
Dual supplies only: single-supply implementations are common with biasing; filter function is unchanged.

Common Pitfalls:
Miswiring that flips to positive feedback; forgetting to bias for single-supply operation; loading that alters Q and center frequency.

Final Answer:
Correct