Abstract: A direct way of generating wideband radar signals which is based on high-speed digital to analogue conversion is introduced in this paper. Wideband linear frequency-modulated digital signals is generated directly by using the polyphase decomposition technology,and by adopting the circuit of equalizer, filter and upconverter and so on. The generation of wideband radar signals with 1. 3 GHz bandwidth is realized finally. The application of the technology greatly improves the magnitude and phase characteristics of the signals and enhances the performance concerning signal phase linearity and the spurs among pulse, hence the imaging ability and dynamic range of the radar get great improvement. The developed system used to generate wideband signals has been applied to certain X band phase array radar successfully.