Fujitsu Develops CMOS-based Power Amplifier Operating at 77GHz

(Business News & Technology News, 5 Feb 2008)

Fujitsu Laboratories Ltd has developed a millimeter-waveband power amplifier (PA) using standard 90nm CMOS process technology. Targeting millimeter-wave applications, Fujitsu Labs developed a standard CMOS modeling technology and design techniques to minimize high-frequency signal loss, thereby enabling the development of what is claimed to be the world's first CMOS-based PA that operates at 77GHz. The technology realizes CMOS radio frequency (CMOS RF) front-end circuitry that includes a PA, thereby enabling integration with baseband circuitry on a single chip, for use in millimeter-wave automotive radar systems.

This technology is being presented at the International Solid-State Circuits Conference (ISSCC) 2008 in San Francisco (February 3 to 7).

Fujitsu Labs developed the following two technologies that make it possible to apply standard CMOS technology to millimeter-wave amplifiers:
1. Modeling technology for transistors and passive components operating in the millimeter waveband
- Fujitsu Labs established a transistor model that shows the operating characteristics at millimeter-waveband and developed parameter-extraction method technology. Researchers also optimized the structure of transmission lines, capacitors, and other passive components, and developed structures that minimize resistive losses.

2. Matching circuit design
- To keep the circuitry compact, Fujitsu Labs developed a "short stub" matching circuit and integrated it with the power-supply circuitry in a way that would further reduce signal losses. This reduced the amount of chip space required by the matching circuit to one-tenth previous levels, and also reduced signal loss to 0.4dB.

Fujitsu Labs' new technology makes it possible to implement 77GHz automotive radars using inexpensive standard CMOS technologies. These developments could also be used to extend the transmission range of wireless communications systems in the 60GHz band.

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