Basic RF Characteristics of the Microstrip Line Employing Periodically Perforated Ground Metal and Its Application to Highly Miniaturized On-Chip Passive Components on GaAs MMIC

Abstract

In this study, highly miniaturized on-chip impedance transformers employing periodically perforated ground metal (PPGM) were developed for application to broadband low-impedance matching. In order to realize a broadband operation by using an equal ripple transfer characteristic over a passband, a three-section transformer was designed by mapping its reflection coefficient to the Chebyshev function. The three-section transformer showed a good RF performance over a broadband (1.5–13 GHz) including ultra-wideband. The size of the three-section transformer was 0.129 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$hboxmm^2$</tex> , which is 2.3% of the size of the transformer fabricated by a conventional microstrip line. Using the PPGM structure, a highly miniaturized on-chip Wilkinson power divider with a low port impedance of 13 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$Omega $</tex> was also developed, and its size is 0.11 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$hboxmm^2$</tex> , which is 6% of the size of the one fabricated by the conventional microstrip line. In addition, in this study, the PPGM structure was theoretically characterized using a conventional capacitive loaded periodic structure. Using the theoretical analysis, basic characteristics of the transmission line with PPGM were also investigated in order to evaluate its suitability for application to a development of miniaturized on-chip passive components. According to the results, it was found that the PPGM structure is a promising candidate for application to a development of miniaturized on-chip components on monolithic microwave integrated circuits.