(This article has been accepted for publication in IEEE Transactions on Circuits and Systems--II: Express Briefs.)This article presents a novel simultaneous wireless power and data transfer (SWPDT) system that combines inductive and capacitive couplings, featuring full-duplex communication with high data transfer rates. Specifically, the power and forward data are transferred through inductive coupling respectively by means of the DD coils and Q coils, while the backward data is transferred through capacitive coupling by means of the stray capacitances. Because of the decoupling characteristic of the DDQ coil structure and the use of two coupling types, the interferences among the power, forward data, and backward data are relatively low. By integrating the two coupling types, a comprehensive circuit model of full-duplex data transfer is established and analyzed. Finally, a 145-W prototype is actualized with 91.4% power transfer efficiency. The forward and backward data transfer rates are 150 kbps and 600 kbps, respectively, demonstrating the feasibility of the proposed system.