Power integrity optimization on USB power distribution network for EMI reduction

The main purpose of this paper is to present the method to reduce the electromagnetic interference (EMI) noise of universal serial bus (USB) hub product. Traditionally, there are a large number of methods used to reduce the EMI noise. Some methods severely increase the cost of product; some methods only improve power integrity (PI) of USB power distribution network (PDN) to a limited extent. In this paper, the present method can reduce EMI noise effectively by PI improvement using few decoupling capacitors (de-caps). More specifically, de-caps placement and value selection are the key parameters that are used to control the PDN behaviors. The results show that the present method is easy to implement and it reduces the EMI noise effectively.