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NEC Journal of Advanced Technology

No.3 (Summer, 2005) Special Issue: Device Technologies Supporting IT / Network Integration

Vol.2 No.3 (Summer, 2005)


KUNIO Takemitsu
Associate Senior Vice President

In the last few years, our daily use of IT has evolved and spread at an astonishing rate. The primary factors of this evolution have been the Internet’s shift to broadband, and the spread of 3G (3rd generation) mobile phones. It is expected that the Internet connecting area will spread rapidly into digital home appliances and car navigation systems in addition to working in conjunction with personal computers and mobile phones. We believe that that area, either consciously or subconsciously, will continue to grow.

Feature Papers

TORII Sunao, SAKAI Junji, INOUE Hiroaki
TOKUE Tatsuya, ITO Yoshiyuki

We propose several techniques of Asymmetric Multi-processing (AMP) for mobile application processors. In our AMP architecture, multiple general purpose processors are integrated on a chip to reduce hardware development period and cost. Our techniques are well considered the role of hardware and software to maximize the benefits of parallel processing. The hardware is carefully designed to enlarge bus bandwidth, shorten memory latency, and reduce power consumption. Our software techniques realize application-level compatibility with single processor and excellent real-time performance with solving multi-processing issues. Moreover, our novel security techniques enable to execute download non-secure native application. We implemented these techniques on the mobile application processor MP211. Evaluation results show our AMP techniques on MP211 are very useful for future mobile terminals.

OHATA Keiichi, MARUHASHI Kenichi, ITO Masaharu, NISHIUMI Toshio

Millimeter-wave broadband transceivers with data rates as high as 1.5Gbps have been developed on the unlicensed 60GHz-band. A direct ASK modulation and demodulation scheme is adopted for the 60GHz-band transceiver. The Traveling Wave Switch (TWSW) as an ASK modulator and an integrated HJFET data driver realizes ultra fast 60GHz-band modulation. To enable a highly producible and compact transceiver module, CPW MMICs and planar filters are flip-chip mounted in TX and RX LTCC MCMs, which are assembled on printed wiring boards using BGA connection. 1.25Gbps full duplex wireless Gigabit Ethernet transceivers having a function to convert a 1000BASE-SX optical fiber link seamlessly to a wireless link, a 1.485Gbps uncompressed HDTV wireless transmission system and so on have been commercialized.

KATOH Toshihiro, KAJITA Mikihiro, NAKAYAMA Naoya

This paper describes the LSI and circuit technologies used in the SX-8 supercomputer. The SX-8 achieves high-speed operation and a superior price/performance ratio by using the leading-edge CMOS technology that was developed in cooperation with NEC Electronics. This technology features a high-performance transmission circuit design and noise reduction technology.

KIKUCHI Katsumi, SAKAI Jun, NAKASE Koichiro, MURAI Hideya
INOUE Hirobumi, HONDA Hirokazu, KATA Keiichiro, BABA Kazuhiro

We developed a high-performance Flip-Chip Ball Grid Array (FCBGA) based on an ultra-thin, high-density packaging substrate called a Multi-Layer Thin Substrate (MLTS) in order to meet the high demand for high-density, high-performance, and low-cost LSI packages. The most important feature of the package is that it has a high-density, high-performance MLTS formed by removing a metal plate after mounting an LSI chip on it. A prototype high-density FCBGA exhibited excellent long-term reliability. The electrical simulation results indicate that the MLTS packaging technology has the advantage of excellent high-frequency properties compared with a FCBGA using a conventional build-up PWB substrate.

HARADA Takashi, WABUKA Hiroshi, KUSUMOTO Manabu
OGAWA Masatoshi, SATOH Shunji, KOSUGE Junji

Recent progress trend in electronics supported by high-speed signal processing of semiconductor chips and high-density packaging technologies reduce layout margins and bring packaging design difficulties. To reduce the time loss by the rework and increase packaging design efficiency in the early stage of product development, short turnaround-time estimation techniques for analyzing the electrical performance integrating chip-package-board characteristics have been required. This paper describes a fast board-power-voltage fluctuation analysis system to realize the chip-package-board co-design.

MAKITA Kikuo, NAKATA Takeshi, SHIBA Kazuhiro, TAKEUCHI Takeshi

Two types of waveguide photodiodes (WG-PD) - an evanescently coupled photodiode (EC-WG-PD) and a separated-absorption-and-multiplication avalanche photodiode (WG-APD) - were developed for use in 40Gbps receivers. The EC-WG-PD is much more robust than a conventional WG-PD under high optical input operation because of its distributed absorbed optical power density along the light propagation in the waveguide. The EC-WG-PD simultaneously exhibited a high external quantum efficiency of 70% for both 1,310 and 1,550nm, a wide bandwidth of >40GHz, and as high as 10mA photocurrent operation. The WG-APD, on the other hand, has a wide bandwidth of 35GHz and a gain-bandwidth product of 140GHz as a result of its small waveguide mesa structure and a thin multiplication layer. Record high receiver sensitivities of -19.6dBm at 40Gbps were achieved.


Researcher Interview Reports

Senior Manager, System Devices Research Laboratories

We are sometimes astonished by the recent advances in cellular phones and digital home appliances that feature a wide range of new capabilities. These advances are supported by the system LSI technology, which integrates a large number of functions on a single chip. However, as the advances have also increased the burden on the field of development, design technologies that enable quick and efficient development are urgently required at the present time.
The technology regarded as the mainstream one among the new design technologies is “C-based design,” that employs C-language, which is an established language in the field of software for enabling circuit design by simply describing its behavior. We here report an interview with Dr. Kazutoshi Wakabayashi at the NEC System Devices Research Laboratories, who is an international authority on this technology, who is also the developer of the high- level design automation system “CyberWorkBench.”

Dr. Jaw-shen TSAI
Research Fellow , Fundamental and Environmental Research Laboratories

“The quantum computer” is attracting great expectations and attention for its innovative operating principles and its capability for solving problems that have been difficult to solve for traditional computers. Although, until only a few years ago it was said that its implementation would take a hundred years or so, several promising research results that seem to approach realization are now being announced from all over the world. Among these results, the achievements made by NEC’s Fundamental and Environmental Research Laboratories are highly evaluated as forming the forefront of the field. The details of this research are difficult for the layman to understand but in order to help explain it, we have interviewed Dr. Jawshen Tsai, a Research Fellow at the laboratory about the significance and the challenges of his research.

Assistant Manager , System Platforms Research Laboratories
Dr. Akihisa TOMITA
Principal Researcher , Fundamental and Environmental Research Laboratories

It has been widely considered that “There is no humanly produced encryption that is not decipherable.” Even if a cipher that is based on factorization theory such as the current RSA encryption is not decipherable, it is because “It takes too much time using a currently available computer” and not because it is indecipherable in principle. However, when a code based on the “uncertainty principle” of quantum mechanics is applied, it is reported that an encrypted communication is realized that is absolutely impossible to be decrypted. This is the “ultimate encryption,” which is a research topic that is presently more advanced than the “quantum computer” research in the field of practical quantum-based research. NEC now stands as a world leader in this research, with successes at the highest level in terms of length and speed of successive cryptographic key generation, under practical conditions. This achievement is a very interesting theme. In this article, we interviewed two researchers in this field who are working in different departments.

New Device & Its Technology

SAKAMOTO Toshitsugu

Nanoscale electronic devices such as molecular or atomic devices have been extensively investigated in order to overcome the limitations in silicon-based microelectronics. One of the intriguing phenomena is a conductance switching caused by the creation or annihilation of a nanoscale metallic bridge in a solid electrolyte[1,2]. The solid electrolyte switch (namely, NanoBridge) has a simple structure of potentially 4F2 and has a low ON resistance, which is lower than that of FETs by two orders of magnitude.

SATOH Masaharu

With the aim of realizing a more affluent world it seems likely that in the future a wide variety of intelligent devices will be widely spread over all corners of society. Energy devices are increasingly becoming a part of the sophisticated input that are supporting this trend. The batteries for the next-generation ubiquitous applications are therefore likely to require a short charging time, a long life cycle, high power and energy densities, and environmental friendliness.
The organic radical battery (ORB) is a new class of rechargeable battery that is being uniquely developed by NEC. It uses the electrochemical reaction of organic radical compounds. This technology was initially proposed by NEC in 2001[1]. Due to the high reactivity and reversibility of the radical reaction, the organic radical battery demonstrates a rapid charging capability and good cycleability[2]. Additionally, organic radical polymer appropriate for forming the flexible thin film battery. ORB contains no harmful heavy metals, and thus opens up a new field of ubiquitous devices with environmentally friendly battery.
Figure 1 shows the positions of several energy devices and the ORB prototype cell. The ORB overcomes the limitations of the conventional energy devices with regard to high power density problems.
This paper describes the properties and the potential applications of the ORB.