Body Area Networks are a new communication technology optimized for low power devices and operation on, in and around the human body to serve a variety of applications including medical, consumer electronics and personal entertainment. This paper shows a system design intended to develop an ultra low power body area network. We show the advantages of using chaotic-pulse based UWB for developing an ultra low power PHY and develop modifications to the chaotic UWB design for improved performance, reliability, mass production and meeting worldwide spectrum regulations. We provide support for data rates from 100 kbps to 10 Mbps with our chaotic based UWB system design in different channel models to satisfy wide variety of applications with power consumption estimated to be in the order of 30-40 mW, during active data communication, assuming a 0.13μ CMOS process.