Design Considerations of Miniaturized Least Dispersive Periodic Slow-Wave Structures

• Published in: IEEE transactions on microwave theory and techniques 2008-02, Vol.56 (2), p.467-474
• Main Authors: Chengzhi Zhou, Yang, H.Y.D.
• Format: Article
• Language: English
• Subjects: Applied sciences; Bandpass; Branch-line coupler; Circuit properties; Cutoff frequency; Delay; Dispersion; Dispersions; Distributed parameter circuits; Electric, optical and optoelectronic circuits; electromagnetic bandgap (EBG); Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronic tubes, masers; Electronics; Exact sciences and technology; Group delay; Joining; Metallization; Microelectronic fabrication (materials and surfaces technology); Microwave circuits; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Passive components; Periodic structures; Photonic band gap; Prototypes; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; slow wave; Transmission lines
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2007.914633

Slow-wave structures using distributed periodic inductive and capacitive loadings have found many microwave circuit applications as left-handed (bandpass) or right-handed (low-pass) transmission lines. A large slow-wave factor (SWF) could result in a much smaller passive component, but also a much lower bandgap (cutoff) frequency and a larger dispersion. This paper addresses the issues and the design tradeoff between the SWF, group delay (dispersion), and the cutoff frequency of a right-handed (low-pass) quasi-lumped transmission line. A new two-layer transmission line structure using 3-D substrate metallization with an SWF of 5.8 is designed. A prototype of a 3-GHz branch-line coupler with a 70% size reduction using such a transmission line structure is fabricated and tested.