Simultaneous switching noise impact to signal eye diagram on high-speed I/O

Simultaneous Switching Noise (SSN) is increasing with higher I/O data rate, resulting into more challenges in regulating 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 optimally. PDN design goal is to reduce the power supply noise going into I/O circuit. Engineering efforts are focused on packaging and board routing in order to control the impedance profile and supply voltage droop within the design specification. This paper discusses the next level of investigation, quantifying the effect of supply noise to the I/O transistor level circuit performance, specifically on Universal Serial Bus (USB) transmitter circuit. Output of the USB´s transmitted signal is shown in eye diagram with the existence of supply noise throughout PDN. Results show that the USB transmitter circuit can sustain with higher supply noise drop than the targeted PDN design.