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512 Mb Mobile SDRAM with on-chip error-correction code (ECC), which supports either single or double data rate and operates on a 1.8 V power supply, is developed. The ECC circuit is optimized with respect to the increase in the chip area and the access-time penalty. The ratio of ECC area increase compared with the conventional mobile DRAM is 15%, and the fast comparing circuits of built-in Hamming code technique check 12 cell data simultaneously and satisfy the specification of 400Mbps DDR SDRAM. The self refresh period at standby state shows about 6 times increase reducing the self refresh current to be less than 100uA at 85degC. The newly adopted DCCS in the ECC, which is resistant from the clustered failures, and the concurrent row redundancy produce a synergistic fault-tolerance effect. The reliability could be 106 times higher by the ECC than that of the conventional DRAM.

We have investigated negative remanence in Co NP system. The Co NPs were uniquely fabricated by using a laser irradiation technique. Magnetization measurements performed on Co NP system show negative remanence taken at temperatures higher than 92 K. The observed negative remanence correlates to the blocking temperature of superparamagnetism. Although we have no clear explanation for negative remanence, this behavior is associated to the magnetic coupling characteristic between the superparamagnetic Co and antiferromagnetic CoO.

Self refresh current in modern DRAMs is becoming more difficult problem to handle because the decreasing cell transistor size has a negative effect on the uniformity of capacitor charge. In order to solve this issue, adaptive self refresh(ASR) scheme has been developed. A dual period based refresh is performed in the ASR scheme to reduce power dissipation using row register information. The row register information is adaptively modified according to the cell data retention characteristics. When DRAM enters self refresh mode, only the rows which were activated for write are tested using internal refresh test circuits. The test results are used to choose the appropriate period for the dual period base self refresh operation. This paper demonstrates 512M mobile SDRAM utilizing this adaptive self refresh(ASR) capability to minimize standby power to 150 uA @85degC while maintaining chip area of the conventional scheme using the same process technology.

In this paper, we explain XML schema for describing the user?s preference on sound fields using MPEG-21 DIA (Digital Item Adaptation) and the real-time implementation algorithm for adapting audio contents to sound field preference. MPEG-21 DIA standards define XML schemas (syntax and semantics) for describing the consumption environments of multi-media resources to adapt or transform multimedia resources such as terminal environment, user?s characteristics, and/or network environments. We propose XML schema to present user?s preference on a sound field as a room impulse response or perceptual parameter set. We also suggest a novel adaptation algorithm for sound field preference. For adapting audio contents to a sound field, they shall be convolved with the room impulse response of the sound field. For real-time application, the fast circular convolution algorithm in frequency domain was used instead of linear convolution in time domain.