The sideband separating (2SB) receiver can simultaneously observe upper sideband (USB) and lower sideband (LSB) signals, enhancing observation efficiency and avoiding spectral confusion. It has extensive applications in the observation of broadband complex astronomical spectral lines. However, due to the inevitable gain and phase mismatches in the analog components of the two signal transmission paths, the sideband suppression ratio of an all-analog sideband separating receiver system is relatively low. To solve this problem, a wideband real-time digital sideband separating receiver prototype based on field programmable gate array (FPGA) has been designed and constructed, which utilizes digital signal processing techniques to achieve real-time calibration of the amplitude and phase of the two intermediate frequency signals. Laboratory tests demonstrate that within the entire 1024 MHz radio frequency bandwidth, the prototype achieves a sideband suppression ratio of over 30 dB, effectively enhancing the receiver's performance.