SAS Expander Design Based On Signal Integrity

Serialization has been the apparent trend as a high performance I/O technology. Serial attached SCSI (SAS) is a kind of serial disk connection technology. SAS chip, adapter, disk driver and SAS expander build up a SAS storage system. SAS expander is responsible for communications between initiator and target devices. It supports up to 3.0Gbps data rate.High data rate makes storage system performance better, meanwhile, crosstalk problem among signal occur. Moreover, with the increment of integrate circuit switch rate and PCB density, signal integrity has become one of the significant problem in high-speed PCB design process. To fully consider SI and take effective methods has been a hot topic in PCB design field.In this paper, as to design and implement steady and high quality switch device that is SAS expander, high-speed PCB design methods are discussed and analyzed. A deep research is made on signal integrity problems such as reflection, crosstalk, and Simultaneous Switching Noise (SSN). Then the solutions to reduce reflection are given. At last, simulation is made to decide the plan against SAS expander system. The author finished the PCB design of high speed data sampling system with the help of EDA tools, the development period is shortened and the cost is reduced, proving analysis of SI is very important to high speed PCB design.