Pulse Generator Delivers 500-ps Output Pulse Width At 40-mV Amplitude

Unlike other RF systems, which use a narrowband carrier, impulse-radio-Ultra-Wide-Band (IRUWB) wireless communication is carrierless. It utilizes short pulse signals to transmit data over a very wide spectrum for short-range, high-data-rate applications. Tung-Yuan Tzou and Fu-Chiarng Chen of Taiwan's National Chiao Tung University have developed a circuit to generate a higher-order derivative Gaussian pulse for IR-UWB applications.

The wide signal bandwidth of IR-UWB signals may overlap with existing narrowband systems, however. This fact prompted the United States Federal Communications Commission (FCC) to set a spectral mask for the usage of the UWB transmission signal. The pulse generator developed by the researchers generates waveforms that are suitable for high-data-rate transmissions while satisfying the FCC's spectral-mask requirements. The higher-order derivative Gaussian pulse waveforms generated by their source have a duration of hundreds of picoseconds. They have been found to perform adequately in indoor UWB systems. Because these pulse waveforms are transmitted without filtering, the architecture's complexity is decreased without degrading system performance.

The new pulse generator is designed and fabricated using TSMC's 0.18-µm CMOS technology for IR-UWB applications. The generator's output pulse width is 500 ps with an amplitude of 40 mV peak to peak. The circuit generates symmetrical and low-ringing pulses in the frequency band from 3.1 to 10.6 GHz allocated by the FCC for UWB applications. The generator's power consumption is about 18 mW. See "New 0.18-mm CMOS Pulse Generator for Impulse Radio Ultra-Wideband Communication Systems," Microwave and Optical Technology Letters, February 2007, p. 342.