Investigation of pulse dispersion in a carrier-based UWB system with LO leakage cancellation

Abstract

Local oscillator (LO) leakage in a carrier-based ultrawideband (UWB) system is a major design concern. In many cases, mixer LO-RF isolation is not sufficient and the LO leakage is well above the useful UWB signal. However, this leakage can be substantially reduced by using a notch filter located before the UWB transmitting antenna as long as it will not lead to unacceptable signal distortion. Therefore, various filter parameters, such as the filter order and 3 dB rejection bandwidth, have been studied to see their effects on providing sufficient band rejection level to reduce the unwanted LO leakage while minimizing the transmitted pulse dispersion. Time domain simulations and measurements have been utilized to evaluate the pulse dispersion using both the relative signal's first pulse amplitude and the pulse time delay spread. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.