FPGA Overview

Field Programmable Gate Arrays as name indicates are programmable gate arrays. FPGAs are the integrated circuits that consist of an array of logic cells. FPGAs also contain flip-flops (memory elements). An FPGA can contain tens of thousands of logic cells and flip-flops. I / O blocks surround the logic cells. These blocks are programmable. Through blocks the gate array is programmed. FPGAs are commonly used in digital signal processing (DSP), data storage, instrumentation, and telecommunication.

FPGA Basic Functionality

An FPGA is a semiconductor device. It consists of programmable logic cells, programmable interconnects, and memory elements such as flip-flops. Logic cells offer the functionality of combinational logic circuits such as decoders. These gates are programmed to provide functionality of basic gates such as AND, OR, NOT, or XOR. Programmable interconnects are programmed to connect logic blocks when required. Logic blocks and interconnects are re-programmable. This allows using an FPGA as any embedded system.

FPGA Specifications

An FPGA is usually specified by its memory, I / O interfaces, logic families, IC packages, and performance specifications.

FPGA Memory

Memory choices for FPGA include CAM (content addressable memory), RAM (random access memory), FIFO (first in first out), LIFO (last in last out), and FLASH memories.

FPGA Performance

Performance of an FPGA varies depending upon three factors. These include internal frequency, total number of I / O ports, and integrated PLLs (phase locked loops) and DLLs (delay locked loops).

FPGA Input / Output Interfaces

I / O interface choices for FPGA include AGP (advanced graphic port), PCI (peripheral component interconnect), and BLVDS (bus low voltage differential signaling).

FPGA Logic Families

Field Programmable Gate Arrays (FPGAs) are available in a wide range of logic families. These include Transistor-Transistor Logic (TTL), Complementary oxide semiconductor (CMOS), crossbar switch technology (CBT), Emitter Coupled Logic (ECL), Gallium Arsenide (GaAs), Silicon On Sapphire (SOS), integrated injection logic (IIL), Gunning with transceiver logic (GTL), and gunning with transceiver logic plus (GTLP). In TTL technology transistors are used as digital switches. ECL technology transistors steer the current through gates. These gates compute the logic functions. In CMOS technology two field effect transistors (FETs) are combined to implement the logic gates. These include PMOSFET and NMOSFET mostly known as PMOS and NMOS.

FPGA IC Packages

Variety of field programmable gate array (FPGA) Integrated circuit (IC) packages depends upon the different number of pins and flip-flops. Most common IC packages include BGA (ball grid array), SIP (single inline package), DIP (dual inline package), QFP (quad flat package), and SOP (small outline package). These packages have further variants. Tape BGA and Plastic BGA are BGA variants. Others are low profile QFP, thin QFP, Ceramic DIP, plastic DIP, and thin SOP.

FPGA Applications

FPGA was the largest competitor of CPLD as it targeted to glue logic for PCBs. But now FPGA has advanced to be used in variety of industrial and embedded applications. These include DSP (digital signal processing), aerospace and defense, medical imaging, computer vision, speech recognition, ASIC prototyping, software defined radio, computer hardware emulation, bio-informatics, cryptography, and a wide range of such applications.