Power Integrity (PI) is a popular topic in today's electronic equipment industry because recent electric equipment uses various ICs, ex. Microprocessor, Memory, FPGA and ASIC. In addition, PI typically has lower source voltage and larger current required. To realize robust design, better power distribution network (PDN) is required. Good PDN means it can supply stable source voltage even if source current changes due to operation of ICs. It requires lower impedance characteristics of PDN from ICs. This paper describes how to characterize the PDN and how to correlate the measurement data and simulation data to realize better PI design.