Getting Started

What Are FPGAs?

Field Programmable Gate Arrays (FPGAs) are programmable semiconductor devices that are based around a matrix of configurable logic blocks (CLBs) connected via 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.

See below for details on each highlight area of the block diagram.

Figure 1

FPGA block structure.

IOB Details

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 (see figure below) 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.

CLB Details

The Configurable Logic Block is the basic logic unit in an 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. A high level CLB overview is shown here. More architectural details can be found in the applicable device´s data sheet.

DCM Details

Digital clock management is provided by most FPGAs in the industry (all Xilinx FPGAs have this feature), and has nearly eliminated the skew and other issues that designers had to face with in designing global signals into FPGAs in the past.

Common FPGA Features

Today’s 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.  Following are the basic components in an FPGA.

Configurable Logic Block (CLBs)

The CLB is the basic logic unit in an 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.

Interconnect

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.

Memory

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 10 Mbits of on-chip memory in 36 kbit 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.

FPGA Solutions, Applications and End-Markets

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 markets and applications such as

End Markets

• Aerospace & Defense
  Radiation-tolerant FPGAs along with intellectual property for image processing, waveform generation, and partial reconfiguration for SDRs.
• Automotive
  Automotive silicon and IP solutions for gateway and driver assistance systems, comfort, convenience, and in-vehicle infotainment.
• Broadcast
  Solutions enabling a vast array of broadcast chain tasks as video and audio finds its way from the studio to production and transmission and then to the consumer.
• Consumer
  Cost-effective solutions enabling next generation, full-featured consumer applications, such as converged handsets, digital flat panel displays, information appliances, home networking, and residential set top boxes.
• Industrial/Scientific/Medical
  Industry-compliant solutions addressing market-specific needs and challenges in industrial automation, motor control, and high-end medical imaging.
• Storage & Server
  Data processing solutions for Network Attached Storage (NAS), Storage Area Network (SAN), servers, storage appliances, and more.
• Wireless Communications
  RF, base band, connectivity, transport and networking solutions for wireless equipment, addressing standards such as WCDMA, HSDPA, WiMAX and others.
• Wired Communications
  End-to-end solutions for the Reprogrammable Networking Linecard Packet Processing, Framer/MAC, serial backplanes, and more

Technology Solutions

• DSP
  The Xilinx XtremeDSP™ initiative helps you develop tailored high performance DSP solutions for aerospace and defense, digital communications, multimedia, video, and imaging industries.
• Embedded Processing
  Xilinx delivers an innovative and flexible range of processing solutions for your unique embedded applications.

ASIC and FPGAs have different value propositions, and they must be carefully evaluated before choosing any one over the other. Information abounds that compares the two technologies. What is provided here is a high level overview of the pros and cons of each:

While FPGAs used to be selected for lower speed/complexity/volume designs in the past, today’s FPGAs easily push the 500 MHz performance barrier. With unprecedented logic density increases and a host of other features, such as embedded processors, DSP blocks, clocking, and high-speed serial at ever lower price points, FPGAs are a compelling proposition for almost any type of design.

FPGA vs. ASIC Design Flow Comparison

The FPGA design flow eliminates the complex and time-consuming floorplanning, place and route, timing analysis, and mask / re-spin stages of the project since the design logic is already synthesized to be placed onto an already verified, characterized FPGA device.

However, when needed, Xilinx provides the advanced floorplanning, hierarchical design, and timing tools to allow users to maximize performance for the most demanding designs.

What is a CPLD?

A CPLD is a combination of a fully programmable AND/OR array and a bank of macrocells. The AND/OR array is reprogrammable and can perform a multitude of logic functions. Macrocells are functional blocks that perform combinatorial or sequential logic, and also have the added flexibility for true or complement, along with varied feedback paths.

Traditionally, CPLDs have used analog sense amplifiers to boost the performance of their architectures. This performance boost came at the cost of very high current requirements. CoolRunner™-II CPLDs, created by Xilinx, use an innovative all-digital core to achieve the same levels of performance at ultra-low power requirements. This allows designers to use the same CPLD architecture for both high-performance and low-power designs.

The removal of analog sense amplifiers also makes the architecture scaleable, allowing for aggressive cost reduction and feature enhancement with each successive process generation.

Additional Resources

• CoolRunner-II RealDigital Technology (PDF)

Why use a CPLD?

CPLDs perform a variety of useful functions in systems design due to their unique capabilities.

• Reprogrammable - Change your design instantly for no cost as many times as you like, build reconfigurable systems, fix ASIC bugs, upgrade system functions anytime from anywhere; Saves time, lowers cost, simplifies design.
• Simple and easy to use - Designing with CPLDs is simple and easy, fits easily into existing design flow; Saves time, lowers cost, simplifies design.
• Low cost - Reprogram to fix system bugs, low unit cost, replace TTL and ASSPs to reduce board components and improve reliability; lowers design cost, lowers system cost, lowers maintenance cost.
• Nonvolatile - Programming kept on power down, CPLD functions available instantly on system power up, almost impossible to steal stored design; Improves security, simplifies design.

Why use Xilinx CPLDs?

As the market leader in programmable logic solutions, Xilinx provides a total solution to a designer's CPLD needs:

• Advanced Silicon - Cost-optimized chip design, high performance, low power operation, the widest range of packaging, advanced system features, highest I/O per macrocell counts.
• Free, powerful design tools - The ISE® WebPACK™ design tools offer the most complete, easy-to-use desktop software solution for developing any Xilinx CPLD.
• Everything else - Free reference designs and application notes, a design kit to get you started, a vast network of distributors, sales representatives, field application engineers, and in-house technical support, and a wide array of online technical documentation.

Selecting the FPGA or CPLD for Your Design

Xilinx FPGA Offerings

Virtex Series FPGAs - Lowest Power High-Performance FPGA

The Xilinx Virtex® series was the first line of FPGAs to offer one million system gates. Introduced in 1998, the Virtex product line consistently offers the industry's leading combination of performance, capability, and integration at the lowest system cost.

Spartan Series FPGAs - Lowest Total System Cost

Xilinx Spartan® FPGAs are ideal for low-cost, high-volume applications. With over 120 million units shipped since 1998, Spartan series FPGAs provide a reliable, efficient, and low-cost path to realize your time-to-market requirements.

Xilinx Solutions

Xilinx programmable logic solutions help minimize risks for electronic equipment manufacturers by shortening the time required to develop products and take them to market.

You can design and verify the unique circuits in Xilinx programmable devices much faster than by choosing traditional methods such as mask-programmed, fixed logic gate arrays. Moreover, because Xilinx devices are standard parts that need only to be programmed, you are not required to wait for prototypes or pay large nonrecurring engineering (NRE) costs.

The software component of this solution is critical to the success of every design project. Xilinx software solutions provide powerful tools that make designing with programmable logic simple. Push-button design flows, integrated online help, multimedia tutorials, and high-performance automatic, and auto-interactive tools help you achieve optimum results. In addition, the industry's broadest array of programmable logic technology and EDA integration options deliver unparalleled design flexibility.

Leading-edge silicon products, state-of-the-art software solutions, and world-class technical support make up the total solution that Xilinx delivers.

Xilinx CPLD Offerings

Whether you need low-power, high-performance or a combination of the two, Xilinx has a CPLD solution to fit your design challenge. Plus, you can take the next step and purchase CPLD devices from the online store.

CoolRunner Series

• CoolRunner™-II
  This cost-optimized 1.8V RealDigital CPLD family provides high performance, ultra low power, advanced system features, and the highest I/O count per macrocell of any competing CPLD.
    
• CoolRunner XPLA3
  This 3.3V low power CPLD family includes Fast Zero Power ™ (FZP) design technology that offers performance and price making them ideal for portable and wireless applications.

XC9500 Series

• XC9500XL
  This 3.3V low-cost CPLD family provides the high performance, expansive feature set, and flexibility demanded by today's cutting-edge system design.
   
• XC9500
  The 5V XC9500 CPLD brings you all the benefits of programmable logic in one cost-optimized, easy-to-use family. Flexibility, simplicity, performance, and low-cost.

Table 1

* Lowest system power consumption can be achieved with the CoolRunner-II advanced feature DataGATE.

Xilinx CPLDs Provide Maximum Design Benefits

Understanding the features and benefits of using CPLDs can help enable ease of design, lower development costs, and speed products to market.

CPLD Benefits at a Glance:

• Ease of design
• Lower development costs
• More product revenue for your money
• Reduced board area
• Increased system reliability
• Speed your product time to market

Get started now by following these four easy steps:

Step 1: Choosing a CPLD

In choosing the CPLD that is right for a design, you need to make the following determinations (the priority of each will vary according to your design):

Density and I/O

• You can find the size of Xilinx CPLD required (logic density and I/O) for your design by submitting your design to the free downloadable ISE® WebPACK™ software

Performance

• Xilinx CPLDs come in a variety of speed grades so that you only pay for the performance you need. Use ISE WebPACK to determine the speed grade you need to meet your system timing requirements.

Voltage and Power

• Different Xilinx CPLD families have different voltage (supply and I/O) and power (standby and dynamic) requirements.

Packaging

• Xilinx CPLDs come in a range of packages, from inexpensive QFP packages to ultra small chip-scale pages, to high-I/O-count BGA packages.

Xilinx CPLD Families

• CoolRunner™ Series
  The CoolRunner Series of Xilinx CPLDs feature the lowest-power, highest-performance devices in the industry. These CPLDs deliver advanced features to support system-level designs such as I/O banking, sophisticated clock control, and superb design security.
    
• XC9500 Series
  Offered in 5.0V (XC9500 family) and 3.3V (XC9500XL family) versions, these low-cost CPLD families provide the high performance, expansive feature set, and flexibility demanded by today's cutting-edge system design.

Step 2: Choosing a Software Package

CPLD and Simple FGPA Designs

To implement basic CPLD or FPGA designs, you will need our free ISE WebPACK software tool.

Any CPLD/ FPGA Designs

Beyond ISE WebPACK software tools, Xilinx offers a variety of software packages to meet various design requirements. Click here to determine the software package that best fits your designing needs.

Step 3: Implementing a Design

After selecting a CPLD device and downloading the necessary software, implementing the design is next. Implementation includes:

• Design entry
• Programming and testing the prototype
• Documentation

Each of the CPLD product pages contain links to supporting application notes, reference designs, development boards, configuration tools, and other useful information to help complete designs quickly and easily.

Step 4: Purchasing CPLDs

There are several ways to purchase Xilinx solutions:

• Xilinx Online Store
• Xilinx North American or international distributors

Each outlet offers silicon, software, programming hardware and more. The Xilinx sales offices and customer support center make sure that the use of Xilinx CPLDs is a simple and satisfying experience.

The design environment and supporting resources are a critical component 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

Design Software Tools

An integrated suite of software tools providing 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.

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.

The Xilinx website has a comprehensive database of Xilinx and third-party verified and tested cores. To find them, visit the Xilinx IP Center.

Education Services

Xilinx Education Services provides a range of beginner to advanced level classes, online and in-person, to jump-start your FPGA design knowledge.

Titanium Dedicated Engineering

Improve your design productivity and accelerate your time to market with Titanium Dedicated Engineering. This program provides you with a dedicated remote or on-site application engineer on a contract basis.

Documentation and Design Kits

Hundreds of application notes and reference designs are available along with detailed data sheets, development boards, and much more to help you evaluate and architect your design.

Xilinx Design Services (XDS)

Get the skills and experience in system, logic and embedded software design you need through Xilinx Engineering Services. XDS helps you optimize your budget, schedule and project performance requirements.

Additional Information

Xilinx provides a wealth of information, training, and resources to get you started designing with FPGA.

Following are recommended next steps:

• Download the free ISE® WebPACK™ software and see the easy to use FPGA design flow for yourself
• Learn using the free Xilinx ISE software tutorial that comes with supporting design files
• Attend a Xilinx FPGA training class near you and connect with Xilinx instructors and other customers