Filter bandwidth — by definition, the bandwidth (BW) of a band-pass (or band-stop) filter is the span between its two half-power (−3 dB) frequencies. Is this correct?

Introduction / Context:
Bandwidth is a fundamental descriptor of how wide a filter’s pass (or stop) region extends around a center frequency. The industry-standard definition uses the half-power (−3 dB) points for linear time-invariant systems unless otherwise specified.

Given Data / Assumptions:

• Band-pass or band-stop context.
• Power proportional to voltage squared in constant-impedance systems.
• Half-power corresponds to 1/√2 in voltage magnitude (−3 dB).

Concept / Approach:
The half-power frequencies f1 and f2 are where the output power is half the peak (or where |H(jω)| drops by 3 dB from the reference). The bandwidth BW is defined as f2 − f1. This convention is ubiquitous in communications and filter design, enabling consistent comparison of selectivity and Q (Q ≈ f0 / BW for narrowband band-pass filters).

Step-by-Step Solution:

Verification / Alternative check:
Standard texts and datasheets define bandwidth using −3 dB points unless a different metric (e.g., ripple limits) is explicitly stated.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing −3 dB (voltage) with absolute voltage drop; mixing alternative definitions used in specific standards without noting the context.

Final Answer:
True