High-Speed Design and Other PCB Considerations

This chapter discusses high-speed design and other printed circuit board (PCB) considerations. Field-programmable gate arrays (FPGA) presented in pin grid array (PGA) packages were predominantly used for military applications; the norm for commercial applications was the plastic quad flat package (PQFP) with pins presented around the perimeter of the device. These shortcomings led to the development of ball grid array (BGA) package that has an array of pads presented across the bottom face of the device. The circuit board is created with a corresponding set of pads. Each pad on the FPGA has a small ball of solder attached to it. These devices are attached to the circuit board by placing them in the correct location and then melting the solder balls to form good ball-to-pad connections. The advent of new format, FPGA Xchange , allow the circuit board tools and the FPGA tools to share common definitions of device aspects, such as how signal names have been assigned to physical device pins. This will allow board designers and FPGA engineers to pass data between their two domains quickly and easily.