Ultra Wideband Wireless Interconnects
With the increasing integration density and operation frequency of CMOS IC in era of sub-100nm , the traditional metal wire interconnect technology is emerging as the major bottleneck to the performance improvement of NoC (Network-on-Chip) system which use the network concepts to analyze and design SoCs. This limit is due to the global interconnect delay becoming significantly larger than the gate delay . Though some process solutions have been developed to address this annoying problem, no remarkable effects are got and nearly all of them are costly. Thereby, UWI technology for high data rate inter-chip and intra-chip communication naturally becomes the attractive alternative.
UWI technology, which distances are measured in a few to tens of centimeters and data rates are Gb/s, is based on low-loss dispersion-free microwave signal transmission, near-field capacitive coupling, Antenna-on-Chip (AoC) communication and modern multiple-access algorithms etc. Such a technology, motivated by the low cost of RF transceivers, can be purely CMOS based and provide ultra-wide bandwidth (~100-Gbps in the near future) as well as on-line reconfigurability for multiple transmitters and receivers. Also, using UWI in a clock distribution system can reduce the latency in clock trees, which might help reduce clock skew and eliminate the frequency dispersion problem. It will ultimately promote the maximum clock frequency.
Wireless interconnects has been considered as one of the greatest potential technologies for current and future system integration, An application example at present is wireless interconnects between on-board 2-D planar chips or stacked 3-D chips for Network-on-Chip (NoC) application. UWI technology is a very new approach and much work on different topics remains to be done before it becomes a viable candidate to replace global wires.