We propose a wide-band passive equalization method for high-speed serial chip-to-chip input/output channels using wave propagation, reflection, and coupling effects on a tightly coupled transmission line structure. This design offers precise control of wideband equalization and low-power consumption as compared to previous active and discrete passive equalizers. Significant improvements. in timing jitter and voltage margin are successfully demonstrated for a data rate of 12.5 Gbps on a 40 cm long backplane printed circuit board.