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The authors have proposed a new capacitive power transfer (CPT) system using one-pulse switching active capacitor (OPSAC). The proposed system improves transfer power without LC resonance so that it is robust against parameter change. The one of advantages of OPSAC is easy realization of cascade connection in order to enhance transfer power. In the past, CPT system with five-stage OPSAC was successfully realized, but the actual transfer power was smaller than theoretical power. In this paper, loss factor is analyzed using precise calculation model. In addition, from the results of loss analysis, it was clarified that the one of the main loss factor is diodes of rectifier so that the system using synchronous rectifier is also proposed for power improvement.

Time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) are investigated for the reliability of (Ba/sub 0.5/Sr/sub 0.5/)TiO/sub 3/ (BST) thin films. TDDB characteristics show a lifetime longer than 10 years at +1 V for BST films with an SiO/sub 2/ equivalent thickness (t/sub eq/) of 0.70 nm. The breakdown is strongly affected by leakage current properties, and does not depend on the dielectric constant. SILC is studied at +1V in time domain after stress charge injection into BST films. 10 year operation for Gbit-scale DRAMs can be guaranteed in spite of the charge loss caused by SILC.