In the high-speed bandwidth acquisition and playback system, due to the current hardware conditions, it is impossible to directly sample the signal at the RF end. Therefore, first complete the down-conversion in the RF module, reduce the signal to the intermediate frequency, and then realize the digitization of the intermediate frequency signal. In response to this problem, a field programmable logic array chip (FPGA) and AD9680 were selected to process the intermediate frequency signal. Use AD9680 to collect the mid-band pass signal with a center frequency of 750 MHz and a bandwidth of 400 MHz as a signal source for test verification, and then pass through a parallel multiphase digital down-conversion module to achieve spectrum shifting. It is verified by testing that the design can normally process the intermediate frequency signal, and the out-of-band suppression reaches 60 dB, which meets the design requirements, has high stability, and has high application value in engineering applications.