A Study of a Versatile Low Power CMOS Pulse Generator for Ultra Wideband Radios

Ultra-Wideband (UWB) technologies are at the forefront of wireless communications, offering the possibility to provide extremely high data rate wireless solutions. In addition to high data rate applications, UWB technologies also offer an extremely low cost alternative for many low data rate systems. In this thesis, we describe the design of a CMOS pulse generator for impulse based UWB systems. The structure of our pulse generator is based on the topology of a single tap CMOS power amplifier. By increasing the number of taps on a CMOS power amplifier, it is possible to generate sub-nanosecond pulses with a desired shape. A power saving scheme that significantly reduces the power consumed at low data rates is also described. The versatility of our design lies in the ability to support dynamically varying output power levels and center frequencies. Our pulse generator design is extended to a rectified cosine generator, necessary for a multiband approach. The performance of our pulse generators is estimated through simulation with a target technology of TSMC 0.18 µm CMOS at a supply voltage of 1.8 V. The simulation results indicate that our pulse generator produces high fidelity Gaussian monocycle pulses with a pulse width of approximately 160 ps and a peak output power of more than 10 mW. We believe that our design of a CMOS pulse generator for UWB systems is a feasible option for many applications in which power and cost are most important.