What is an FPGA? Field-programmable gate arrays (FPGAs) are a class of devices classified or called as field-programmable logic (FPL). FPGAs are programmable semiconductor devices that are based on a matrix of configurable logic blocks (CLBs) connected through programmable interconnects .
The LUT is a RAM-based function generator and is the main resource for implementing logic functions. Furthermore, the LUTs in each slice pair can be configured as distributed RAM or a 16-bit shift register. Each of the two LUTs (F and G) in a slice has four logic inputs (A1–A4) and a single output (D) (see Fig. 1.7 ).
Given their inherent configurability and relatively low development cost, the impact of FPGA circuits on various engineering directions has grown with a rapid pace. FPGAs are useful for a wide range of applications, such as medical imaging, aerospace and defense, automotive, video and image processing, etc.
In addition to implementing two independent 4-input functions, the ALM can for example, implement a full 6-input LUT or a 5-input and a 3-input function with independent inputs.