A revision of cascade synthesis theory covering cross-coupled filters

Creative Commons License

Yildirim N., Sen O., Sen Y., Karaaslan M., Pelz D.

IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, vol.50, no.6, pp.1536-1543, 2002 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 50 Issue: 6
  • Publication Date: 2002
  • Doi Number: 10.1109/tmtt.2002.1006415
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.1536-1543
  • Keywords: cross-coupled, filters, linear phase, synthesis, BANDPASS WAVEGUIDE FILTERS, TRANSMISSION ZEROS, MICROWAVE FILTERS, LINEAR-PHASE, DESIGN
  • Middle East Technical University Affiliated: No


The classical zero-shifting technique is generalized to cover extraction of complex transmission zeros (TZs) in the form of fourth-order LC sections whereby the jomega- and alpha-axis TZs appear as special cases. Using this approach, bandpass filters can be synthesized in direct coupled resonator forms by pole placement instead of designing them through low-pass prototypes. By using circuit transformations, the resulting direct coupled resonator filter circuits can then be transformed into a variety of cross-coupled forms like a fully cross-coupled form or cascaded N-tuplet form. It is shown that one or more finite jomega-axis, alpha-axis, or complex TZs can be extracted as direct coupled resonator circuit blocks, which can be converted into cross-coupled triplets, quadruplets, or other N-tuplets of resonators. In particular, it is shown that a cascaded quadruplet section can be used to realize a complex TZ quadruplet s(i) = +/-sigma(i) +/- jomega(i), as well as two pairs of jomega-axis TZs, s(i) = jomega(i), and s(k) = jomega(k).