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Toshiba receiver targets millimeter-wave apps

Posted: 20 Jun 2007 ?? ?Print Version ?Bookmark and Share

Keywords:millimeter-wavecommunication? receiver ICs? Toshiba chips?

Toshiba Corp. has unveiled a 60GHz receiver CMOS chip that it said can drastically lower the cost of devices for emerging millimeter-wave communication applications.

The advance was presented at the recent 2007 Symposia on VLSI Circuits in Kyoto, Japan.

The test chip measures 2.4-by-1.1mm. All required receiver function blocksincluding an antenna, low-noise amplifier, mixer (down converter) and a PLL synthesizerwere integrated using a 90nm CMOS process. "We integrated a PLL synthesizer on chip and believe that it's the first chip that operates alone as a receiver," said Toshiya Mitomo, a researcher at the Toshiba Mobile Communication Laboratory.

Millimeter-wave communication chips operating at 60GHz have previously been fabricated with GaAs. GaAs modules required the integration of an antenna and a synthesizer separately using bonding wire. The result is a bulky, expensive device.

By contrast, Toshiba's CMOS device promises to lower fabrication costs to one-tenth the cost of a GaAs module, claimed laboratory leader Koji Ogura.

When CMOS process technology is applied at high frequencies like a 60GHz receiver, however, silicon substrates easily leak signals. Parasitic elements are generated at wiring interconnects on the substrate in blocks such as the amplifier and the mixer. The fab problems make chip operation unpredictable.

To solve them, Toshiba engineers used a fully differential structure, including a differential on-chip dipole antenna. Mitomo said that the differential structure is already being used in devices like mobile phones but is relatively rare in 60GHz devices. By adding noise and parasitic elements in opposite phases as a way to cancel them, the structure drastically suppresses their influence, he added.

Toshiba's test chip operated in the 61.5GHz range with power gain of 22dB.

- Yoshiko Hara
EE Times

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