Sunao Torii

On-Chip Optical Interconnect

We describe a cost-effective and low-power-consumption approach for on-chip optical interconnection. This approach includes an investigation into architectures, devices, and materials. We have proposed and fabricated a bonded structure of an Si-based optical layer on a large-scale integration (LSI) chip. The fabricated optical layer contains Si nanophotodiodes for optical detectors, which are coupled with SiON waveguides using surface-plasmon antennas. Optical signals were introduced to the optical layer and distributed to the Si nanophotodiodes. The output signals from the photodiodes were sent electrically to the transimpedance-amplifier circuitries in the LSI. The signals from the photodiodes triggered of the circuitries at 5 GHz. Since electrooptical modulators consume the most power in on-chip optical interconnect systems and require a large footprint, they are critical to establish on-chip optical interconnection. Two approaches are investigated: 1) an architecture using a fewer number of modulators and 2) high electrooptical coefficient materials.

FIDES: An advanced chip multiprocessor platform for secure next generation mobile terminals

We propose a secure platform on a chip multiprocessor, FIDES, in order to enable next generation mobile terminals to execute downloaded native applications for Linux. Its most important feature is the higher security based on multigrained separation mechanisms. Four new technologies support the FIDES platform: bus filter logic, XIP kernels, policy separation, and dynamic access control. With these technologies, the FIDES platform can tolerate both application-level and kernel-level bugs on an actual download subsystem. Thus, the best-suited platform to secure next generation mobile terminals is FIDES.

Skew-Tolerant Global Synchronization Based on Periodically All-in-Phase Clocking for Multi-Core SOC Platforms

A periodically all-in-phase clock generator and a skew-tolerant bus wrapper have been developed for multi-core SOC platforms. The clock generator produces clock frequencies in 81-steps, and the bus wrapper makes possible deterministic data transfer among different frequency clocks even when inter-clock skew is as high as 2 clock cycle times. A combination of the clock generator, the bus wrapper, and loosely balanced global clock distribution serves to ease chip-timing design while maintaining deterministic chip behavior.

Multitasking Parallel Method for High-End Embedded Appliances

Embedded appliances such as high-end cell phones require not only high performance but also a performance guarantee. The authors demonstrate a performance guarantee framework using an asymmetric multiprocessing approach. They implemented the proposed method on a multicore processor using Linux. Evaluation results show that the method improves the performance guarantee while maintaining software compatibility.