Coplanar Waveguides for MMIC Applications: Effect of Upper Shielding, Conductor Backing, Finite-Extent Ground Planes, and Line-to-Line Coupling

• Published in: IEEE transactions on microwave theory and techniques Vol. 35; no. 3; pp. 260 - 267
• Main Authors: Ghione, G., Naldi, C.U.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.1987; Institute of Electrical and Electronics Engineers
• Subjects: Application specific integrated circuits; Applied sciences; Circuit properties; Conductors; Conformal mapping; Coplanar waveguides; Coupling circuits; Electric, optical and optoelectronic circuits; Electronics; Exact sciences and technology; Gallium arsenide; Impedance; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwave integrated circuits; MMICs; Planar waveguides; Gallium Arsenides; Microwave line; Interconnection; Network analysis; Integrated circuit; Coupled line; Microwave circuit; Coplanar line; Shielded line; Computer aided design
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.1987.1133637

Parasitic effects occurring in actual realizations of coplanar waveguides (CPW) for microwave integrated circuits on GaAs substrates, such as the influence of an upper shield, conductor backing, finite-extent ground planes, and line-to-line coupling, are discussed and evaluated. CAD-oriented analytical expressions are obtained for the electrical quasi-TEM parameters of the relevant waveguiding structures by means of exact or approximate conformal mapping techniques. Differences in electrical behavior with respect to ideal CPW's are highlighted, and practical design criteria are obtained for keeping cover height, ground-plane width, and line-to-line spacing effects to a minimum.