Eigenmode Analysis of Propagation Constant for a Microstrip Line with Dummy Fills on a Si CMOS Substrate

Yuya ONO  Takuichi HIRANO  Kenichi OKADA  Jiro HIROKAWA  Makoto ANDO  

IEICE TRANSACTIONS on Electronics   Vol.E94-C   No.6   pp.1008-1015
Publication Date: 2011/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E94.C.1008
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Analog Circuits and Related SoC Integration Technologies)
silicon CMOS,  microstrip line,  propagation constant,  dummy fill,  eigenmode analysis,  periodic structure,  millimeter wave,  

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In this paper we present eigenmode analysis of the propagation constant for a microstrip line with dummy fills on a Si CMOS substrate. The effect of dummy fills is not negligible, particularly in the millimeter-wave band, although it has been ignored below frequencies of a few GHz. The propagation constant of a microstrip line with a periodic structure on a Si CMOS substrate is analyzed by eigenmode analysis for one period of the line. The calculated propagation constant and characteristic impedance were compared with measured values for a chip fabricated by the 0.18 µm CMOS process. The agreement between the analysis and measurement was very good. The dependence of loss on the arrangement of dummy fills was also investigated by eigenmode analysis. It was found that the transmission loss becomes large when dummy fills are arranged at places where the electromagnetic field is strong.