2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

IEEE Transactions on Microwave Theory and Techniques
Volume 48 Number 5, May 2000

Table of Contents for this issue

Complete paper in PDF format

Quasi-TEM Characteristic Impedance of Micromachined CMOS Coplanar Waveguides

Mehmet Ozgur, Veljko Milanović, Christian Zincke, Michael Gaitan and Mona E. Zaghloul

Page 852.

Abstract:

Micromachined coplanar waveguides (CPW's) fabricated in CMOS technology consist of glass-encapsulated metal conductor strips, fully suspended by selective etching of the silicon substrate. The minimum amount of etching necessary for proper operation of the micromachined waveguides is determined by using an isolation criterion. In this paper, the quasi-TEM characteristic impedance of a CPW is derived, including the finite conductor thickness and the thicknesses of surrounding dielectric layers. The employed analytical approach is based on conformal mapping and the partial capacitance technique. The losses both in conductor and dielectric layers are neglected. The analytical results and proposed approximations are verified by integral-equation computation and by measurement of various sample structures.

References

  1. "IEEE Trans. Microwave Theory Tech. (Special Issue on Innovative Integration Techniques for Microwave and Millimeter-Wave Circuits)", vol.  48, Nov.  1998.
  2. V. Milanović, M. Gaitan, E. D. Bowen and M. E. Zaghloul, "Micromachined coplanar waveguides in CMOS technology", IEEE Trans. Microwave Theory Tech., vol. 45, pp.  630-635, 1997.
  3. W. Heinrich, "Quasi-TEM description of MMIC coplanar lines including conductor-loss effects", IEEE Trans. Microwave Theory Tech., vol.  41, pp.  45-52, Jan.  1993.
  4. R. E. Collin, Foundations for Microwave Engineering, 2nd ed.   New York: McGraw-Hill, 1992.
  5. K. C. Gupta, R. Garg, I. Bahl and P. Bhartia, Microstrip Lines and Slotlines, 2nd ed.   Norwood, MA: Artech House, 1996.
  6. C. P. Wen, "Coplanar waveguide: A surface strip transmission line suitable for nonreciprocal gyromagnetic device applications", IEEE Trans. Microwave Theory Tech., vol. MTT-17, pp.  1087-1090, Dec.   1969.
  7. C. Veyres and V. F. Hanna, "Extension of the application of conformal mapping techniques to coplanar lines with finite dimensions", Int. J. Electron. , vol. 48, pp.  47-56, 1980.
  8. G. Ghione, "A CAD-oriented analytical model for the losses of general asymmetric coplanar lines in hybrid and monolithic MIC's", IEEE Trans. Microwave Theory Tech., vol. 41, pp.  1499 -1510, Sept.  1993.
  9. C. Chang, W. Chang and C. Chen, "Full-wave analysis of multilayer coplanar lines", IEEE Trans. Microwave Theory Tech., vol. 39, pp.  747-750, Apr.  1991.