Shigeo Nara

Characteristics of phase-delay time on meander differential signal lines and a shielded meander differential signal line

Differential signal transmission lines, which are advantageous in high-speed signal processing, have often been used. However, the phase-delay characteristics and the characteristics of Sdd21 when these differential signals are transmitted through meander lines remain unknown. In the present paper, the phase-delay and Sdd21 characteristics of the meander differential signal lines were analyzed, and shortening the phase-delay time by the corner was examined on three types of differential signal lines: the coupled microstrip, the edgecoupled stripline, and the broadside-coupled stripline. In addition, the effect of shielding on the phase-delay time of the shielded broadside-coupled stripline was examined.

Study on the Characteristics of S21 and EMI on a Shifted Electromagnetic Band Gap (EBG) Structure

AI-EBGs attenuate the through characteristics with broad bands of high frequency. AI-EBGs have structures in which sections of low characteristic impedance and high characteristic impedance are arranged periodically. However, the characteristics of radiated EMI of AI-EBGs are not well known. In this study, the characteristics of S21 and EMI are examined when the patch and the branch sizes are varied while the size of the printed circuit board and the number of patches are kept constant. In addition, the characteristics of S21 and EMI are examined when the dielectric thickness is varied. An AI-EBG structure with a thin dielectric is found to give the optimal S21 and EMI characteristics. Finally, a shifted EBG structure is proposed.