Abstract: With the combination of three different size L-bridge units, a novel multi-period planar ultra-wideband EBG structure was designed on the power layer of the multilayer PCB, which can be used to suppress the simultaneous switching noise in the digital circuit system. The structure of the EBG was modeled and simulated by using the electromagnetic simulation software HFSS. On the basis of simulation, the realistic EBG structure was fabricated . The measurement results are well consistent with the simulation ones. The stop band width of combined-structure EBG is improved significantly when compared with traditional L-bridge EBG . When the inhibition of depth is set to -40 dB, the new EBG structure exhibits an ultra-wide-band stop-band characteristics from 0.8 GHz to 9.5 GHz.