Comparison of commercially available FPGA architectures

Field Programmable gate arrays (FPGAs) are erasable, programmable PLDs and structurally, can be divided into three classes: symmetrical arrays, row-based, and hierarchical PLDs. The architecture, interconnection structure, and advantages and limitations of each class are discussed and a comparison between these classes is made. As an example of each class, FPGAs from Xilinx, Altera, and Actel are considered