A filter is an electrical network that can transmit signals within a specified frequency range.

The frequency range is called pass band and the other frequency band where the signals are suppressed is called as attenuation band or stop band.

The frequency that separates the pass and attenuation band is known as cut-off frequency.

The cut-off frequency is usually symbolized as fc in case of unique or by f1 and f2 in case the cutoff frequency are more than one (f1 indicates lower cut-off frequency and f2 indicates higher cut-off frequency).

Lesson 9

Filters – Lesson 9
Engineering Institute of Technology