The millimeter-wave frequency band of 5G wireless communication has become the research direction of the future mobile communication field because of its large bandwidth and high speed. However, in the millimeter wave frequency band, the signal generator needs to realize the configuration of different signal bandwidths. In response to this problem, this paper designs a parallel interpolation structure combining a fast FIR filter and a polyphase interpolator, which can expand the transmission bandwidth range of the 5G millimeter-wave signal generator, and has high interpolation efficiency, low power consumption, and low resource consumption. Advantages such as low occupancy rate. The experimental verification results after simulation and optimization show that, without affecting the demodulation results, the interpolation structure proposed in this paper reduces the use of fast FIR interpolator DSPs by 25% compared with the traditional 4-channel parallel 4-times interpolator. The use of LUTs is reduced by 15.2%, and the power consumption of DSPs is reduced by 23.8%, which meets the actual needs of low system resource occupancy and low power consumption. The results have been applied to domestic 5G base station comprehensive testers.