As a new type of radar jamming signal, the signal quality of ultra-wideband (UWB) comb spectrum interferes with the performance of electronic countermeasures. Considering the low operating frequency range, large resource consumption, and slow data generation of a traditional digital comb spectrum generator, a high-speed digital UWB generation method of the comb spectrum is proposed in this paper. In the proposed method, the simulation data are stored in the mass memory chip, and the flexible configuration of the comb spectrum signal is realized by using the table lookup method. Concurrently, we confirm that the rate of single transmission can reach 12 Gbps using the JESD204B high-speed interface, and the operating frequency of the comb spectrum signal generator reaches up to the C-band under the first Nyquist region. Our proposed method saves computing resources during field-programmable gate array operation, enables operation at higher frequencies, and generates signals faster. Finally, a verification platform is developed to verify the effectiveness of the proposed method.