Filter Basics 8: An In-Depth Look At Bandwidth

In Part 3 of our Filter Basics Series, we provided a brief overview of five key filter specifications to understand, one of which was bandwidth. In this post, we are going to look more closely at what bandwidth is and why we need to consider bandwidth when selecting a filter.

First, let’s look at why bandwidth is important. In general, bandwidth is defined as the width of the passband of the bandpass filter and expressed as the frequency difference between the lower and upper 3 dB points. Bandwidth will dictate the data rate, or how quickly we can send information through a channel such as an optical fiber or a section of the radio spectrum.