Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences


UC Berkeley


2009 Research Summary

A Fully-Integrated Wireless Transceiver for cm-Range Wireless Communications

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Simone Gambini, Jan M. Rabaey and Elad Alon

Gigascale Systems Research Center and Intel Fellowship Foundation

Recent years have seen a surge in interest towards the realization of highly energy-efficient wireless interconnections across a range ranging from a few hundreds of microns to a few millimeters. Such an ultra-short range wireless technology has the potential to enable significant cost reduction in applications such as chip testing, multi-chip packaging, and high speed connector replacements.

Transceivers exhibiting a range of a few centimeters could be used to perform tasks such as distributed wireless robotic arm control or smart "electronic" surfaces and user interfaces. The realization of the short-range link, however, poses significant challenges in the following fields:

(1) System integration: with a 5 cm communication range, a very small overall assembly size ( ~1 cm2) is mandatory. This makes the integration of a low-cost, high-efficiency antenna extremely challenging.

(2) System cost: the extremely high node density resulting from the short range (~400 nodes per square meter of active surface) dictates ultimate cost reduction. Any external component, and particularly bulky and expensive crystal time references, should be avoided.

(3) Link robustness: communication reliability should persist in the presence of other short-range communication devices, such as 802.11/WiMedia transceivers.

(4) Power dissipation: overall communication energy should be lower than 60 pJ/Bit.

To achieve these goals, we developed a communication system that exploits ultra-wideband signaling around an 8 GHz carrier to reduce antenna size, RF carrier precision requirements, and transmit energy dissipation. A redundant signaling scheme is used to simplify timing recovery and speed up acquisition, as well as to allow the receiver to mitigate interference with minimal power overhead.

At the current stage, we are completing the development and characterization of broadband small antennas on an FR-4 substrate (Figure 1). Meanwhile, a test chip including a complete transceiver has been submitted for fabrication in a generic 65 nm digital process (Figure 2).

Figure 1
Figure 1: Proposed wideband antennas: hollow circular monopole (top) and inductively loaded circular monopole (bottom) and measured return ratio

Figure 2
Figure 2: Layout capture of submitted test chip

Ishikuro, Sugahara, and Kuroda, "An Attachable Wireless Chip Access Interface for Arbitrary Data Rate Using Pulse-Based lnductive-Coupling through LSI Package," ISSCC 2007.
D.Guermandi, S. Gambini, and J. Rabaey, "1 V 250 Kpps 90 nm CMOS Inductive Coupling Transceiver for cm-Range Wireless Communications," Proc. of ESSCIRC, 2007.