FPGAs

Field-programmable gate arrays (FPGAs) are integrated circuits that can be configured after manufacture to implement digital logic circuits. The core of an FPGA is a fabric consisting of an array of programmable logic blocks connected by a programmable interconnect. Each logic block typically contains a configurable logic element built around look-up tables (LUTs) and flip-flops, enabling both combinational and sequential logic. The fabric is augmented by input/output blocks, clock networks, and specialized resources such as block RAM, DSP slices, and high-speed transceivers. Configuration data, stored in on-chip or external memory, defines the circuit function when the device is powered up.

Programming an FPGA involves mapping a desired circuit to the hardware fabric using a design flow that often starts with a hardware description language such as VHDL or Verilog, followed by synthesis, placement and routing, and bitstream generation. Higher-level synthesis tools and domain-specific languages are also used. FPGAs support iterative design and rapid prototyping, and many devices offer partial or dynamic reconfiguration, allowing parts of the fabric to be reprogrammed while others continue to operate.

Compared with application-specific integrated circuits (ASICs), FPGAs offer lower non-recurring engineering costs and faster time-to-market, at the expense of higher per-unit cost, lower density, and typically lower performance-per-watt for a given function. They provide greater flexibility than fixed-function devices like CPLDs and can host complex digital systems, signal processing, and custom accelerators.

Typical applications include digital signal processing, communications, embedded systems, data-center accelerators, and AI inference. Modern FPGAs include abundant block RAM, DSP resources, and support for high-level interfaces, making them suitable for a wide range of modern computing tasks.

Limitations include power consumption, heat dissipation, and the need for specialized tools and expertise. Ongoing trends emphasize larger fabrics, hardened memory and AI blocks, improved partial reconfiguration, and better performance-per-watt.