SAN FRANCISCO — IBM Research Division’s description of a two-chip, 60-GHz SiGe radio at ISSCC this week holds more surprises than just radio integration.
The research team developed antenna elements packaged on top of the silicon in standard chip-on-board or plastic LGA packages. It also includes dipole, Yagi and patch antennas integrated directly into a package with the two-chip transceiver.
Brian Gaucher, manager of the senior research team responsible for the radio, said IBM migrated through four families of SiGe up to the 8HP process, a 250-GHz Ft BiCMOS SiGe process. The transmitter chip’s IQ interface can accept most forms of modulation, such as OFDM, making it a universal solution for PANs, in-building broadband video distribution or metropolitan-area backhaul.
Tests with an OFDM baseband device demonstrated data rates of 630 Mbits/s, though Gaucher said the demonstrated speed was limited by the test equipment, not RF devices.
The transmitter device converts in two steps from baseband to 9 GHz, then to 60 GHz, while the receive chain performs the conversion in reverse. With all voltage-controlled oscillators, phase-locked loops and filters on the chips and antennas integrated in packages, Gaucher said the only devices outside the chip set were several bias resistors.
In theory, SiGe devices could integrate some baseband functions, though Gaucher said "the intent here is to keep it a general-purpose radio, so if we added baseband, it would become more of an application-specific device."