The field-programmable gate array (FPGA) is a semiconductor device that can be programmed after manufacturing. Instead of being restricted to any predetermined hardware function, an FPGA allows you to program product features and functions, adapt to new standards, and reconfigure hardware for specific applications even after the product has been installed in the field—hence the name “field-programmable”.
You can use an FPGA to implement any logical function that an application-specific integrated circuit (ASIC) could perform, but the ability to update the functionality after shipping offers advantages for many applications.
Unlike previous generation FPGAs using I/Os with programmable logic and interconnects, today’s FPGAs consist of various mixes of configurable embedded SRAM, high-speed transceivers, high-speed I/Os, logic blocks, and routing. Specifically, an FPGA contains programmable logic components called logic elements (LEs) and a hierarchy of reconfigurable interconnects that allow the LEs to be physically connected. You can configure LEs to perform complex combinational functions, or merely simple logic gates like AND and XOR. In most FPGAs, the logic blocks also include memory elements, which may be simple flipflops or more complete blocks of memory.
As FPGAs continue to evolve, the devices have become more integrated. Hard intellectual property (IP) blocks built into the FPGA fabric provide rich functions while lowering power and cost and freeing up logic resources for product differentiation. Newer FPGA families are being developed with hard embedded processors, transforming the devices into systems on a chip (SoC).
Source, Altera corporation (NASDAQ: ALTR)