Simultaneous Switching Noise (SSN) continuously increases with higher data rate, which resulting in more challenges in regulating the supply voltage noise. SSN increases jitter in high-speed interface circuit and limits the performance of I/O. In order to reduce SSN effect to supply voltage droop, Power Distribution Network (PDN) has to be designed wisely. PDN’s design aims to reduce the power supply noise when going into circuit level. Effort was done toward the packaging and board routing in order to control the impedance profile and supply voltage droop within design specification. This paper discusses the next level of investigation on the effect of supply noise to the I/O transistor level circuit performance, specifically focused on Universal Serial Bus (USB) transmitter circuit. Output of the USB’s transmitted signal is shown in eye diagram by the existing of supply noise throughout PDN.