Wideband RF front end design considerations for a flexible white space software defined radio

This paper introduces a flexible RF front end for whitespace communication. The designed front end can operate over any frequency from 100 MHz to 2.5 GHz and the channel bandwidth can be programmable from 4.5 kHz to 10 MHz. This large frequency range and wide bandwidth makes this hardware suitable for implementing most wireless standards. A direct conversion RFIC developed by Motorola, drives the core of the RF front end. The various RF parameters can be changed by programming this RFIC through a serial peripheral interface (SPI). As part of this work we further develop an intelligent software driver to control different parameters of the RFIC. Thus the combination of highly flexible front end and flexible software driver makes this hardware an excellent choice for whitespace devices. The performance of this front end has been tested and measured and has been integrated into a daughterboard format for the Universal Software Radio Peripheral (USRP), a hardware device which enables the rapid design and implementation of software defined radio (SDR).