A cell phone aims at receiving and transmitting information through cellular standards. It can contain up to six chips, each dedicated to a specific function working on a specific standard. In order to accommodate these different wireless standards, multi-band multi-standard devices are highly desired. A Software-Defined-Radio (SDR) can tune to any frequency band, select any reasonable channel bandwidth, and detect any known modulation. A SDR is a one-chip solution which covers all the radio spectrum. This paper presents the design of an analog discrete-time device located in a RF Front End receiver, between the antenna and a Digital Signal Processor (DSP). It uses the principle of the Discrete Fourier Transform (DFT) to fulfil the SDR purpose. An application to RF digital modulation is exhibited.