Structure generation and performance comparison of elliptic G m-C filters

Slawomir Koziel*, Stanislaw Szczepanski, Rolf Schaumann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Starting from a set of matrices describing a general Gm-C filter topology, a procedure is developed for generating structures of lowpass filters. As the matrices and the filter topologies have a one-to-one correspondence, an algebraic method is used to identify filter topologies with desired properties, here, transfer functions with finite jω-axis transmission zeros, specifically elliptic filters. Sensitivity expressions for these structures are derived and a performance comparison based on a set of chosen criteria is made. For a specified elliptic transfer function, filters with only grounded capacitors and those containing also floating capacitors emerge as alternative realizations, as are filters with a single input and those with distributed inputs. For third-order functions, a detailed comparison is performed of leapfrog (LF) and inverse follow-the-leader-feedback (IFLF), the most popular special cases, and of topologies that have also floating capacitors (LFf, IFLFf), as well as of a novel configuration that uses also distributed inputs (DIf) and leads to a reduced element count. Design guidelines and restrictions are given, which follow from the derived results with focus on the circuits' sensitivity performance and other properties important for IC implementation.

Original languageEnglish
Pages (from-to)565-589
Number of pages25
JournalInternational Journal of Circuit Theory and Applications
Issue number6
Publication statusPublished - Nov 2004

Other keywords

  • Elliptic filters
  • Filter synthesis
  • G-C filters


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