This paper presents an efficient quadratic conversion architecture for real-time wideband DDC, it can move IF signal to baseband in two steps. Firstly, IF signal is moved to baseband nearby with the help of an structure based on polyphase filter, which places mixers after polyphase filters. Then, the signal is moved to baseband through conventional orthogonal frequency mixing. This presented architecture can reduce filter resources and effectively reduce the sample rate and process cost. Finally, simulation results are presented to illustrate the validity of the new structure.