Radars are developed with the aim to process any type of signals even in the presence of interferences in a hostile context. The authors propose a circuit which can deal with any signal, whatever its frequency, its modulation scheme. This circuit is based on sampled analogue signal processor (SASP) performing a fast Fourier transform (FFT) using voltage samples. The idea is to process any radio frequency signal from 0 to 5 GHz using the FFT to obtain frequency shifting and filtering, presenting a new approach to reduce dramatically power consumption and thus address radar application such as FOPEN. The measurement results presented here on the SASP have been obtained with a 65 nm CMOS technology from STMicroelectronics. Further, the concept of an active interference-cancelling system using the analogue signal processor in a feed-forward loop is presented.