Reconfigurable architectures FPGA

FPGAs (Field Programmable Gate Arrays) are integrated circuits whose functionality is fully programmable by the user after manufacture. They are an alternative to ASICs (Application Specific Integrated Circuits), whose functionality is totally fixed in the foundry.

FPGAs are a special type of reconfigurable architecture. Their programming process is referred to as configuration. Different types of reconfigurable architecture are distinguished by the level of granularity of the internal programmable elements. In FPGAs, the elements have fine-grained programmable functionality, i.e. for each bit individually. There are thick-grain reconfigurable architectures where functionality is programmable at word level (e.g. 16 or 32 bits).

FPGAs use the most advanced technologies available at any given time (28 nm etching in 2012). Designing an ASIC using these technologies would result in an extremely high-performance system, but at the cost of a colossal investment. It requires a large design team, expensive and complex tools, several months of design work, and a substantial manufacturing budget. What's more, manufacturing lead times at the foundry can be considerable (several months). The design and verification time for an FPGA solution is much shorter than for an ASIC, and requires less effort and personnel. Many of the technical details are handled by the FPGA manufacturer.

FPGAs are manufactured in large volumes, enabling design costs to be shared by all customers. An FPGA costs from a few euros for the simplest, to several hundred (or even thousands) for the most complex. For small production runs, FPGAs are much more affordable than ASICs. Of course, for large volumes, an ASIC solution is more cost-effective.

FPGA configuration mechanisms reduce performance compared with ASIC solutions. Speed is lower and power consumption higher. But their reconfigurability means they can be optimized over time. We can imagine bringing an initial solution to market quickly, then improving it over time (reduced Time-To-Market), or supporting new standards over time without having to "emulate" them in software.

FPGAs deliver the very high performance of hardware, but are quick and easy to use via software configuration. As a result, they can be found in a wide range of applications: high-performance computing, embedded systems, telecommunications, network routers, wireless networks, signal and image processing, medical imaging, computer vision, cryptology, security devices, biomedical sensors, bioinformatics, circuit prototyping and more. FPGAs have become the basic hardware support for complete Systems on Chip (SoC). All functionalities are integrated into the FPGA.