What is an FPGA?

An FPGA, Field Programmable Gate Array, is an integrated circuit which is composed of digital circuit elements which can be configured as required by the design.

This is fundamentally different to a microprocessor which simply executes instructions on clock cycles. An FPGA is more akin to an artists easel where we begin with a blank canvas and end up with digital circuits running within the chip all running at the same time to achieve a desired outcome. FPGA development could be thought of as synthesizing digital circuits by inference.