ABSTRACT
UWB transmission technology is very attractive for its low-cost and low-power communication applications, occupying a very wide frequency range, which was rst proposed for communication systems yet in the 1940s [1]. Since then, it was mainly used for radar-based applications because of the wideband nature of the signal that results in very accuratetiming information. By the early 1970s, the system concept and basic components such as pulse train generators and modulators, detection receivers, and wideband antennas were available [2]. However, due to further development in high-speed switching and narrowband pulse generation technology, UWB has become more attractive for low-cost communication applications, now representing any wireless transmission scheme that occupies a transmission frequency bandwidth of more than 20% of a center frequency, or more than 500 MHz [3]. Such large bandwidths are achieved by using very narrow time-duration baseband pulses of an appropriate shape and duration, including the family of Gaussianshaped pulses and their derivatives. Larger-transmission bandwidths are preferred to achieve higher data rates without the need to increase transmitting power, resulting in the ability for increasingly ne resolution for multipath arrivals, which leads to reduced fading per resolved path since the impulsive nature of the transmitted waveforms prevents signicant overlap and, hence, reduces the possibility of destructive combining. Market considerations require that UWB-based products be implemented in CMOSs to achieve low-power and low-cost integration.
