RF Front-end for Impulse UWB Communication Systems

Abstract

-In this paper, we propose a multi(six)-port radio frequency (RF) front-end including both modulator and demodulator for impulse ultra-wideband (UWB) communication systems. This RF front-end validates full channel (3GHz-4GHz) uniform phase spectrum modulation scheme by using a six-port phase modulator and demodulator. Both the modulator and demodulator adopt the same six-port circuit structure. This kind of quasi-symmetric transceiver front-end is relatively easy to design and fabricate. To validate the proposed RF front-end for UWB communications, a wideband signal with a 1GHz bandwidth is generated from a 2ns pulse and up-converted using a center frequency of 3.5GHz. The 3GHz-4GHz signal is applied to the RF input of a six port modulator and digital data is simultaneously fed to the baseband inputs of the modulator. This operation produces a signal whose phase spectrum is uniformly modulated. Two input ports of the six-port demodulator are fed respectively with the received phase modulated signal and the reference non-modulated signal. The demodulator's four outputs provide different signals used to determine the modulation states with an algorithm based on the six-port circuit features. A proofof-concept experiment has been realized using this multi-port RF front-end and a field programmable gate array (FPGA) based digital signal processing (DSP) platform implementing the demodulation algorithm and synchronization control. Both measurement and simulation results validate the proposed frontend and corresponding algorithms for a 1GHz UWB channel.