Simultaneous switching noise (SSN) is a serious design issue to stabilize logic operation and to reduce electromagnetic interference (EMI) in advanced CMOS circuits and systems. Ringing frequency observed in the SSN waveforms is strongly related to the anti-resonance peak frequency of total PDN impedance. In this paper, on-board snubber (RC series circuit) was investigated to improve power supply integrity in a FPGA (Field Programmable Gate Array) board. The on-board snubber circuits was added just at the beneath of the power supply terminals of the FPGA to effectively suppress the anti-resonance peak of the total PDN impedance. Design space to damp the anti-resonance peak was examined. In particular, the values of on-board capacitance and resistance of snubber circuit has been examined by using circuit analysis tool and field solver.