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Even‐order passive filters: Pascal versus Chebyshev
Author(s) -
Dimopoulos Hercules G.
Publication year - 2013
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.1794
Subject(s) - chebyshev filter , pascal (unit) , chebyshev polynomials , approximation theory , chebyshev nodes , transfer function , mathematics , network synthesis filters , computer science , mathematical analysis , electronic engineering , engineering , electrical engineering , programming language
The recently reported Pascal approximation with non‐equiripple magnitude response leads to transfer functions of order equal or comparable to that of the Chebyshev approximation, offering an alternative to the equiripple Chebyshev approximation. Both approximations can be used in passive filter design and have similar design limitations when the order turns out to be even. In this paper, these design issues are thoroughly addressed, and the exact conditions are set under which even‐order passive Chebyshev and Pascal filters cannot be directly synthesised and either the order has to be increased to the next odd integer value or the modified filter must be designed. Pascal approximation is used for the first time for the design of doubly resistively terminated passive LC filters, and it is shown that the even‐order design issue is much less restricting making Pascal superior to Chebyshev filters in that even‐order filters can be directly designed to meet specifications that cannot be met by Chebyshev filters of the same even order. The theoretical results are confirmed through several design examples. Copyright © 2012 John Wiley & Sons, Ltd.