| Summary: | 博士 === 國立臺灣大學 === 電信工程學研究所 === 101 === This dissertation focuses on the equivalent circuit model, mechanism, and design of the electromagnetic bandgap (EBG) structures for the suppression of ground bounce noise. Developing a miniaturized and stopband-enhanced EBG structure is the main goal of this dissertation. In the beginning, we propose a method for determining the lower- and upper-bound cutoff frequencies of bandgaps. The method helps us not only to predict where the bandgap is but also to understand what mechanisms of the lower- and upper-bound cutoff frequencies are. Instead of solving the dispersion relation, we propose that the lower- and upper-bound cutoff frequencies can be determined by the resonant frequencies of the unit cell with appropriate boundary conditions. Based on the proposed method, two approaches are developed for constructing the physics-based models of one- and two-dimensional EBG structures, respectively. For the case of one-dimensional EBG structure, we can use an equivalent circuit model consisting of transmission-line sections to electrically characterize the electromagnetic behavior of a unit cell. As regards the two-dimensional EBG structure, an equivalent circuit model for the unit cell is developed to predict the lower- and upper-bound cutoff frequencies. The values of the circuit elements can be extracted by using the derived cavity models. The equivalent circuit models can provide us a design concept for relating the geometry of the EBG structure to the corresponding bandgap behavior.
Two novel designs of EBG structures are proposed in this dissertation. The first one is the multiple vias EBG structures. The mechanisms of lower- and upper-bound cutoff behaviors and the corresponding frequencies of the EBG structure are investigated and explained. By sweeping the via pitch of the multiple vias EBG structure, we can find an optimized design for achieving the maximum bandwidth ratio. Under the assumption of the same dimension, the absolute bandwidth and bandwidth ratio are enhanced by the multiple vias EBG structure when compared with the mushroom EBG structure. The other design is the interleaved EBG structure for the wider bandwidth and smaller area. The improvements on lower- and upper-bound cutoff frequencies of the interleaved EBG structure can be achieved at the same time by reducing the pitch of power/ground vias pair. Based on the design concept, the interleaved EBG structures with multiple pairs of power/ground vias are also proposed to enhance the bandwidth of bandgap further. For the interleaved EBG structure with single pair of power/ground vias as an example, the electrical size of the unit-cell length, which is normalized to the wavelength in the substrate, and bandwidth ratio are 0.071 λgL and 139 %, respectively. Compared with the conventional mushroom EBG structure proposed in the past literatures, the interleaved EBG structure with single pair of power/ground vias simultaneously shows substantial improvements on bandwidth of 51.1 % and miniaturization of 61.2 %. With regard to the interleaved EBG structure with four pairs of power/ground vias, the bandwidth has an increase of 115.2 % wider than that of the conventional mushroom EBG structure and the required layout area can be reduced by 30.5 % simultaneously.
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