With the rapid development of modern high speed digital circuits, simultaneous switching noise(SSN) problem becomes more and more prominent. A novel wide band planar electromagnetic band gap(EBG) is proposed for the suppression of SSN in high speed digital circuits. The proposed electromagnetic band gap is simulated and analyzed by using Ansoft HFSS. The simulation results show that the -30 dB suppression bandwidth ranges from 0.2 GHz to 5.6 GHz. Compared to the L bridge EBG, the lower cut off frequency is decreased by 500 MHz, the bandwidth is increased by 1.4 GHz, the relative bandwidth is increased by 38.1%. At the same time, it can suppress the simultaneous switching noise omnidirectionally.