What is a FPGA?

Field Programmable Gate Array (FPGA)

FPGAs are programmable semiconductor devices that are based around a matrix of Configurable Logic Blocks (CLBs) connected through programmable interconnects. As opposed to Application Specific Integrated Circuits (ASICs), where the device is custom built for the particular design, FPGAs can be programmed to the desired application or functionality requirements. Although One-Time Programmable (OTP) FPGAs are available, the dominant type are SRAM-based which can be reprogrammed as the design evolves.

FPGAs allow designers to change their designs very late in the design cycle– even after the end product has been manufactured and deployed in the field. In addition, Xilinx FPGAs allow for field upgrades to be completed remotely, eliminating the costs associated with re-designing or manually updating electronic systems.

FPGA Block Structure

FPGA Block Structure

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Common FPGA Features

FPGAs have evolved far beyond the basic capabilities present in their predecessors, and incorporate hard (ASIC type) blocks of commonly used functionality such as RAM, clock management, and DSP. The following are the basic components in an FPGA:.

Configurable Logic Blocks (CLBs)

The CLB is the basic logic unit in a FPGA. Exact numbers and features vary from device to device, but every CLB consists of a configurable switch matrix with 4 or 6 inputs, some selection circuitry (MUX, etc), and flip-flops. The switch matrix is highly flexible and can be configured to handle combinatorial logic, shift registers or RAM. More architectural details can be found in the applicable device’s data sheet.


While the CLB provides the logic capability, flexible interconnect routing routes the signals between CLBs and to and from I/Os. Routing comes in several flavors, from that designed to interconnect between CLBs to fast horizontal and vertical long lines spanning the device to global low-skew routing for Clocking and other global signals. The design software makes the interconnect routing task hidden to the user unless specified otherwise, thus significantly reducing design complexity.

SelectIO (IOBs)

Today’s FPGAs provide support for dozens of I/O standards thus providing the ideal interface bridge in your system. I/O in FPGAs is grouped in banks with each bank independently able to support different I/O standards. Today’s leading FPGAs provide over a dozen I/O banks, thus allowing flexibility in I/O support.


Embedded Block RAM memory is available in most FPGAs, which allows for on-chip memory in your design. These allow for on-chip memory for your design. Xilinx FPGAs provide up to 10Mbits of on-chip memory in 36kbit blocks that can support true dual-port operation.

Complete Clock Management

Digital clock management is provided by most FPGAs in the industry (all Xilinx FPGAs have this feature). The most advanced FPGAs from Xilinx offer both digital clock management and phase-looped locking that provide precision clock synthesis combined with jitter reduction and filtering.

Xilinx FPGAs

Xilinx offers the broadest lineup of FPGAs providing advance features, low-power, high-performance, and high value for any FPGA design. Below is an overview of Xilinx leading FPGA families.

Features Artix™-7 Kintex™-7 Virtex®-7 Spartan®-6 Virtex-6
Logic Cells 215,000 480,000 2,000,000 150,000 760,000
BlockRAM 13Mb 34Mb 68Mb 4.8Mb 38Mb
DSP Slices 740 1,920 3,600 180 2,016
DSP Performance (symmetric FIR) 930GMACS 2,845GMACS 5,335GMACS 140GMACS 2,419GMACS
Transceiver Count 16 32 96 8 72
Transceiver Speed 6.6Gb/s 12.5Gb/s 28.05Gb/s 3.2Gb/s 11.18Gb/s
Total Transceiver Bandwidth (full duplex) 211Gb/s 800Gb/s 2,784Gb/s 50Gb/s 536Gb/s
Memory Interface (DDR3) 1,066Mb/s 1,866Mb/s 1,866Mb/s 800Mb/s 1,066Mb/s
PCI Express® Interface x4 Gen2 Gen2x8 Gen3x8 Gen1x1 Gen2x8
Analog Mixed Signal (AMS)/XADC Yes Yes Yes - Yes
Configuration AES Yes Yes Yes Yes Yes
I/O Pins 500 500 1,200 576 1,200
I/O Voltage 1.2V, 1.35V, 1.5V, 1.8V, 2.5V, 3.3V 1.2V, 1.35V, 1.5V, 1.8V, 2.5V, 3.3V 1.2V, 1.35V, 1.5V, 1.8V, 2.5V, 3.3V 1.2V, 1.5V, 1.8V, 2.5V, 3.3V 1.2V, 1.5V, 1.8V, 2.5V
EasyPath™ Cost Reduction Solution - Yes Yes - Yes
FPGA Applications

Due to their programmable nature, FPGAs are an ideal fit for many different markets. As the industry leader, Xilinx provides comprehensive solutions consisting of FPGA devices, advanced software, and configurable, ready-to-use IP cores for market and applications such as:

By Market By Technology
Aerospace and Defense Industrial Audio
Automotive Medical Security
Broadcast Wireless Communications Video and Imaging
Consumer Electronics Wired Communications  
High Performance Computing    
FPGA Solutions and Services

The design environment and supporting resources are a critical components of the FPGA design environment, as they allow for completing your design quickly and accurately. Xilinx offers the industry's most comprehensive solution, consisting of:

Resource Description
Boards and Kits Xilinx development kits provide out-of-the box design solutions that help evaluate and architect your design. Xilinx also offers Targeted Design Platforms which comprise fully integrated and tested hardware, software and IP, and application framework along with the appropriate design environment.
Documentation Hundreds of application notes, data sheets and reference designs are available to provide you with the technical support you need to start your design.
Intellectual Property Xilinx and its partners offer hundreds of free and for-purchase intellectual property (IP), verified and guaranteed to meet timing parameters, thus speeding up your design cycle and allowing you to focus on the value add components of the design instead of standards conformance.
Software and Design Tools An integrated suite of software tools provide a seamless start-to-end design flow from design entry to configuration (programming the FPGA). Optional add-on software tools are available for your advanced designs to enable features such as custom floorplanning and unique in-chip verification using ChipScope™ Pro software.
Training Xilinx hands-on training programs provide you the foundational knowledge necessary to begin designing right away. These programs target both engineers new to FPGA technology and experienced engineers developing complex connectivity, digital signal processing, or embedded solutions.
Titanium Dedicated Engineering Integrates skilled Xilinx FPGA experts with your team to meet tight deadlines and deliver results. Our experienced engineers provide design expertise to help resolve complex issues, get projects to market faster, and lower production costs.