J. O. (Seán) Scanlan, MRIA, IEEE Life Fellow, (born 1937) is a circuit theorist.
After receiving the BE degree in Electrical Engineering from University College Dublin (UCD) in 1959, Scanlan worked for a number of years in the U.K. at Mullard, Redhill, a leading industrial research laboratory, and received his PhD from the University of Leeds in 1966. He soon acquired a formidable reputation as a scholar of the highest standing and in 1968 was appointed to the Chair of Electronic Engineering at the University of Leeds at the age of 31. He left Leeds to take up the newly created Chair of Electronic Engineering at UCD in 1973, and later became Head of the Department of Electronic and Electrical Engineering. He retired from this position in 2002 and is now an Emeritus Professor at UCD.
Throughout his career Scanlan solved some of the most important circuit theoretic challenges of the time. Initially he contributed to the theory of high frequency transistor amplifiers and oscillators, and that of tunnel diode amplifiers. After making a number of fundamental contributions to the synthesis of lumped networks, he turned to the synthesis of distributed circuits, then exercising the minds of the leading circuit theorists, and working with David Rhodes produced what remain the most important results in distributed circuit synthesis. These methods continue to be central to the design of microwave filters for the most challenging applications.
He also made important contributions to the fields of digital filters and switched-capacitor filters, where he proved the existence of an exact synthesis for switched-capacitor state-variable filters with arbitrary attenuation characteristics, previously thought impossible.
Scanlan founded the successful International Journal of Circuit Theory and Applications and served as Editor from 1973 until 2006, and is now an Honorary Editor.
He was also one of the founders of the biannual European Conferences on Circuit Theory and Design (ECCTD) and served as the Chairman of the first ECCTD in 1972. These conferences have provided an important vehicle for international scientific collaboration within the field; this was particularly significant at a time when collaboration within Europe was not as straight forward as it later became. Like the journal, the conferences have become ever broader in the scope of the applications represented.
Seán Scanlan is a former President of the Royal Irish Academy (RIA) (1993–1996), a life fellow of the Institute of Electrical and Electronics Engineers (IEEE), and is a recipient of the Golden Jubilee Medal of the IEEE Circuits and Systems Society, and of a RIA Gold Medal.