How is the width of the pass band of a bandpass filter typically expressed?

The width of the pass band of a bandpass filter is typically expressed as the frequency difference between the lower and upper relative 3dB points. The 3dB points refer to the frequencies at which the power of the output signal is half of the power at the center frequency, and these points essentially mark the boundaries of the pass band. This measurement indicates the range of frequencies that can pass through the filter with minimal attenuation, providing a clear understanding of the filter’s operational bandwidth.

This approach to defining the pass band width is critical in filter design and analysis, as it gives engineers valuable information about how effectively a filter can allow specific frequencies to pass while attenuating others. The use of the 3dB point is a standard practice in signal processing because it is widely understood and allows for consistent communication across various applications in electronics and telecommunications.