60-GHz CMOS Chips

Professor Behzad Razavi

Professor Behzad Razavi and his students have recently introduced the first highly-integrated 60-GHz CMOS wireless receiver. Operation at 60 GHz will exploit 7 GHz of unlicensed band for transmitting high data rates, paving the way for high-speed wireless links. Such links will not only eliminate the jungle of cables that presently surrounds our office and home electronics, but will also provide much greater mobility for computing and entertainment devices. In fact, a fast real-time connection allows the mobile device to carry much less intelligence than the base serving it and hence benefit from a low cost and a small size. For example, your camcorder may simply transmit the recording to a server rather than store it.

The 60-GHz band offers another interesting capability: miniaturized antennas that can be built on the chip along with the transceiver system. The short wavelength — a few millimeters — at these frequencies allows antennas with dimensions on the order of one millimeter to provide a moderate efficiency. It is now possible to integrate multiple antennas and transceivers on one chip so that they can focus or "steer" the electromagnetic radiation in a desirable direction.

The principal challenge in designing 60-GHz chips relates to the very high operating frequency. Work on RF transceivers has thus far remained mostly below 6 GHz. Running RF circuits at 60 GHz therefore introduces new issues. For one thing, the speed of transistors has not gone up so much as to allow a ten-fold increase in the frequency by a simple redesign of 6-GHz wireless circuits. For another, the parasitics of the wires connecting the transistors on the chip play a much more adverse role in the performance at 60 GHz. These issues are much more pronounced in CMOS realizations.

These design challenges are met through innovations at the architecture, circuit, and device levels. In particular, the receiver developed by Professor Razavi incorporates new circuit and device techniques to achieve a high performance in a standard CMOS technology.