This letter presents the design and measurement of a CMOS impulse-radio ultra-wideband (UWB) impulse generator using IBM 90-nm CMOS technology for the application of 3.1–10.6 GHz UWB systems. The impulse generator has a simplex architecture using digital circuits and passive bandpass filter. The measurement results show great consistency with the simulation results. The impulse generator has a center frequency of 5.8 GHz and consumes an average power of 0.9 mW at 200 MHz pulse repetition frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26137