Filters

Filters do the job of rejecting some signals while allowing others to pass through a communication channel. Filters can be passive and active or as analog and digital. In modern communications, filtering means selecting signals by their frequency. This chapter presents the concept of and the need for filtering, and discusses the principles of operation of the main filter types (in addition to the low‐pass filters): high‐pass filters, band‐pass filters, and bandstop filters. It focuses on op‐amps‐based active filters and their main characteristics and applications as well as on the principle of operation and main applications of switched‐capacitor filters. The chapter examines the need for filter prototypes in filter design, and presents the basics of digital filters, their principle of operations and mathematical description.