Uncovering The Basics Of All Filter TypesSponsored by: NATIONAL INSTRUMENTS

April 14, 2005

A filter is a signal-processing component that removes unwanted parts of an input signal such as noise, extracts useful parts of an input signal lying within a certain frequency range, or reshapes the frequency spectrum of the input signal. Analog filte

Roger Allan

An analog filter comprises electronic components like resistors, capacitors, and op amps. These filters are widely used in noise reduction, video signal enhancement, graphic equalizers, high-fidelity audio systems, and many other areas. Design techniques for analog filters are well known. At all stages of the filter circuit, the signal undergoing filtering is a voltage or current that is the direct analog of the physical quantity involved.

Digital filters are implemented in software as an algorithm. This algorithm can be executed on a digital processor, such as a general-purpose CPU like those found in PCs, or an embedded digital-signal processing unit. Digital-signal processors are popular largely due to their use as digital filters. Field-programmable gate arrays (FPGAs) also can be configured to act as digital filters. The availability of powerful PC platforms with equally powerful graphical user environments simplifies and expedites the design of all digital filter types.

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About the Author

Roger Allan

Roger Allan is an electronics journalism veteran, and served as Electronic Design's Executive Editor for 15 of those years. He has covered just about every technology beat from semiconductors, components, packaging and power devices, to communications, test and measurement, automotive electronics, robotics, medical electronics, military electronics, robotics, and industrial electronics. His specialties include MEMS and nanoelectronics technologies. He is a contributor to the McGraw Hill Annual Encyclopedia of Science and Technology. He is also a Life Senior Member of the IEEE and holds a BSEE from New York University's School of Engineering and Science. Roger has worked for major electronics magazines besides Electronic Design, including the IEEE Spectrum, Electronics, EDN, Electronic Products, and the British New Scientist. He also has working experience in the electronics industry as a design engineer in filters, power supplies and control systems.

After his retirement from Electronic Design Magazine, He has been extensively contributing articles for Penton’s Electronic Design, Power Electronics Technology, Energy Efficiency and Technology (EE&T) and Microwaves RF Magazine, covering all of the aforementioned electronics segments as well as energy efficiency, harvesting and related technologies. He has also contributed articles to other electronics technology magazines worldwide.

He is a “jack of all trades and a master in leading-edge technologies” like MEMS, nanolectronics, autonomous vehicles, artificial intelligence, military electronics, biometrics, implantable medical devices, and energy harvesting and related technologies.