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Hideho ARAKIDA Masafumi TAKAHASHI Yoshiro TSUBOI Tsuyoshi NISHIKAWA Hideaki YAMAMOTO Toshihide FUJIYOSHI Yoshiyuki KITASHO Yasuyuki UEDA Tetsuya FUJITA
We present a single-chip MPEG-4 audiovisual LSI in a 0.13 µm CMOS, 5-layer metal technology with 16 Mbit embedded DRAM, which integrates four 16 bit RISC and dedicated hardware accelerators including a 5 GOPS post filtering unit. It consumes 160 mW at 125 MHz and dissipates 80 nA in the standby mode. The chip is the world first LSI handling MPEG-4 CIF video encoding at 15 frames/sec and audio/speech encoding simultaneously.
Masafumi TAKAHASHI Yasuo YAMADA Emi KANEKO Shinichi YOSHIOKA Haruyuki TAGO
A 10-MIPS peak performance single-chip MCU (Micro Controller Unit) core has been developed for real time applications. The following features are implemented to improve cost-effectiveness and the worst interrupt response: (1) large-scale on-chip register with overlapping register windows, (2) the mechanism of receiving exception request with concurrent execution of another instruction, (3) load-store architecture, (4) optimized instruction pipelining, and (5) two 32-bit internal and a 16-bit external buses. It delivers about 5-MIPS average performance in some benchmark programs. The worst overall interrupt response time, which is defined to be the one from receiving an interrupt request to saving the general registers in the invoked interrupt routine, is measured to be 2.38 µs, which is about three fold improvements over a commercial 32-bit MCU. The prototype contains only 15,000 gates, and is cost-effective for 16/32-bit single-chip MCU.
Yukihito OOWAKI Shinichiro SHIRATAKE Toshihide FUJIYOSHI Mototsugu HAMADA Fumitoshi HATORI Masami MURAKATA Masafumi TAKAHASHI
The module-wise dynamic voltage and frequency scaling (MDVFS) scheme is applied to a single-chip H.264/MPEG-4 audio/visual codec LSI. The power consumption of the target module with controlled supply voltage and frequency is reduced by 40% in comparison with the operation without voltage or frequency scaling. The consumed power of the chip is 63 mW in decoding QVGA H.264 video at 15 fps and MPEG-4 AAC LC audio simultaneously. This LSI keep operating continuously even during the voltage transition of the target module by introducing the newly developed dynamic de-skewing system (DDS) which watches and control the clock edge of the target module.
Masafumi TAKAHASHI Hiroshige FUJII Emi KANEKO Takeshi YOSHIDA Toshinori SATO Hiroyuki TAKANO Haruyuki TAGO Seigo SUZUKI Nobuyuki GOTO
A 250-MIPS, 125-MFLOPS peak performance processing element (PE), which is being developed for an on-chip multiprocessor, has been modeled and evaluated. The PE includes the following new architecture components: an FPU shared by several IUs in order to increase the efficiency of the FPU pipelines, an on-chip data cache with a prefetch mechanism to reduce clock cycles waiting for memory, and an interface to high speed DRAM, such as Rambus DRAM and Synchronous DRAM. As a result, a PE model with an FPU shared by four or eight IUs causes only 10% performance reduction compared to a model with an un-shared FPU model while saving the cost of three FPUs. Furthermore, a PE model with prefetch operates 1.2 to 1.8 times faster than a model without prefetch at 250-MHz clock rate when the Rambus DRAM is connected. It becomes clear that this PE architecture can bring a high effective performance at over 250-MHz, and is cost-effective for the on-chip multiprocessor.