Field programmable gate arrays (FPGA )

Field programmable gate arrays(FPGA) are advanced programmable logic devices. The word field in the name signifies the ability of the gate arrays to get programmed by the users. The word array indicates that series of columns and rows of gates that can be programmed by the end user.
As compared to standard programmable gate arrays , FPGAs are larger devices. The basic cell structure of FPGA is more complex than that of other standard Programmable devices .In FPGA these are known as configurable logic blocks (CLBs).
The FPGA architecture uses three types of configurable elements. the perimeter input/ output blocks (IOBs) , a core array of configurable logic blocks (CLBs) and resources for interconnection. The IOBs provide a programmable interface between internal array of logic blocks and device's external pins. CLBs perform user specific logic functions. And the interconnect resources carry signals among the blocks.
A configuration program stored in internal static memory cells determines the logic functions and their interconnections. The configuration data is loaded in to the device during power up reprogramming functions. FPGA devices are customized by loading configuration data in to the internal memory cells. FPGA device can either actively read its configuration data out of an external serial/ parallel PROM ( master mode ), or configuration can be written to the FPGA device (slave or peripheral modes)