Development of Technology that Achieves World's Most Accurate On-Chip Measurement of Clock Signal Quality

- Supporting design and development of advanced LSI chips -

NEC Corporation (NEC) and NEC Electronics Corporation (NEC Electronics) today announced the development and verification of technology that achieves the world's most accurate on-chip measurement of clock signal quality (jitter). This research was undertaken in an effort to support design and development of new LSI chips, as well as improve their performance and reliability. Results of this research will be presented on February 8 at IEEE International Solid-State Circuits Conference (ISSCC) 2006, being held from February 5-9 in San Francisco, California.

Clock signal quality is the quality of the signals generated inside LSI chips. Deterioration of the signal quality causes malfunction of LSI chips. Although deterioration of LSI chips is predicted during design, and necessary adjustments (margins) are made, current analysis techniques cannot sufficiently assess deterioration of clock signals due to the evolution of miniaturization and large-scale design. This results in the need for large margins in LSI design and development, thus hindering further miniaturization.

Normally, clock timing fluctuation (jitter), which degrades quality, is only measurable once per oscillation period. By copying the clock signal, NEC and NEC Electronics were able to carry out multiple measurements during a single clock cycle's oscillation period. Instead of simply copying the clock signal, the copied clock signals were designed to carry equally distributed information about the time fluctuation. This development has enabled highly accurate measurement of time fluctuations. As a result, it has now become possible to uncover extremely complex problems of next generation LSI chips, which would have been extremely difficult to measure with conventional technology.

The increasing integration density in LSI chips in recent years has resulted in an increasingly complex physical phenomenon, which determines the behavior of the signal inside the LSI chips. To date, it has been difficult to fully comprehend clock signal deterioration in LSI chips that are actually in use or in field, even with analysis developed for predicting deterioration. As integration density continues to get higher, margin expansion will be required to ensure safe operation, hindering continued performance enhancement of LSI chips. In response to this problem, NEC and NEC Electronics embedded a circuit within an LSI chip to measure its signal deterioration, and have developed a new LSI design scheme to allow further performance enhancements as well as actual data observation in the field.

By using this design scheme, it will be possible to gather and analyze the amount of signal quality deterioration inside an LSI chip when it is being used in a system, even while the device is running a program. Therefore, although analysis of deterioration prediction has been carried out to date, demonstrating reliability of an LSI chip or a system in a particular operating environment, the newly developed technology will enable much more efficient design of next generation LSI chips.

In particular, measurement accuracy at a rate of 1pS is expected to play a crucial role in strengthening future LSI design and development as there will be heavy reliance on the amount of quality deterioration in clock signals as they determine LSI operation (and hence LSI margin design).

The research being carried out by NEC and NEC Electronics is vital to the development of technologies for highly accurate measurement of LSI on-chip clock signal quality, as well as supporting the development and improved reliability of advanced LSI chips. Both companies are committed to active research aimed at continuous improvement of these technologies for early and reliable delivery to their customers.
Notes*
(1) Time fluctuation (jitter): Time fluctuation in a periodic signal's oscillation period

About NEC Corporation

NEC Corporation (NASDAQ: NIPNY) is one of the world's leading providers of Internet, broadband network and enterprise business solutions dedicated to meeting the specialized needs of its diverse and global base of customers. NEC delivers tailored solutions in the key fields of computer, networking and electron devices, by integrating its technical strengths in IT and Networks, and by providing advanced semiconductor solutions through NEC Electronics Corporation. The NEC Group employs more than 140,000 people worldwide and had net sales of 4,855 billion yen (approx. $45.4 billion) in the fiscal year ended March 2005.
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About NEC Electronics

NEC Electronics Corporation (TSE: 6723) specializes in semiconductor products encompassing advanced technology solutions for the high-end computing and broadband networking markets, system solutions for the mobile handsets, PC peripherals, automotive and digital consumer markets, and platform solutions for a wide range of customer applications. NEC Electronics Corporation has 26 subsidiaries worldwide including NEC Electronics America, Inc. and NEC Electronics (Europe) GmbH. Additional information about NEC Electronics worldwide can be found at www.necel.com.