Challenges for ultra-wideband (UWB) CMOS integration

Various methods of utilizing the UWB spectrum have been developed to date, characterized by specific modulation schemes, such as pulse position, pulse amplitude or bi-phase modulation. A new method emerging today utilizes a multi-band approach, where information is encoded in multiple RF subbands at staggered time, each occupying 500 MHz bandwidth. A description of multi-band modulation schemes for UWB is included in the paper. The long term vision for UWB-based products is to enable personal devices with integrated wireless connectivity. This requires 110, 200 and 480 Mbps at 10 m, and reasonably low power consumption. UWB requires CMOS designs in order to achieve low power and low cost integration with other devices, and to fulfil the vision of integrated connectivity. One of the design challenges is the high operating frequencies (3.1-10.6 GHz), an additional challenge is that low Q systems are more sensitive to parasitics, especially in pads and wire bonds. Some UWB receiver architectures require good isolation among subbands. They also require quick switching between subbands at different frequencies. Example transmitter and receiver architectures are described in the paper.