Four-port microwave networks with intrinsic broad-band suppression of common-mode signals

• Published in: IEEE transactions on microwave theory and techniques Vol. 53; no. 5; pp. 1569 - 1575
• Main Authors: Fathelbab, W.M., Steer, M.B.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-05-2005; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active circuits; Applied sciences; Bandwidth; Cascades; Circuit properties; Circuit synthesis; Circuits; Common-mode signals; Coupling circuits; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Filtering theory; four-port networks; Frequency ranges; Gain; Matched filters; matching/filtering; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave filters; Microwaves; Network synthesis; Network topology; Networks; Prototypes; pseudodifferential circuits; Rejection; Signal synthesis; transmission zeros; Discriminant analysis; Filtering; Prototype; pseudodifferential circuits; matching/filtering; Common-mode signals; Microwave filter; Implementation; four-port networks; Cascade circuit; Common mode rejection rate; Four port network; Band rejection filter; Subsystem; Microwave circuit; Active circuit; Gain; transmission zeros
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2005.847046

Two classes of four-port microwave networks are defined with discriminative even- and odd-mode transmission characteristics. Design of the networks is based on filter prototypes with predefined sets of transmission zeros and, consequently, a desired response can be synthesized. A configuration consisting of a pseudodifferential active circuit in cascade with either class results in a sub-system with high common-mode rejection ratio over a broad frequency range. A pseudodifferential circuit implementation demonstrated low common-mode gain over a 3:1 operating bandwidth ranging from 250 to 750 MHz.