An Ultimate Guide to FPGA - FPGA Board Design

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Mon, Dec 07, 2020

FPGA and FPGA Boards

FPGA of PCBONLINE

Field Programmable Gate Array or FPGA, are integrated circuits, which can be configured by the designer after getting manufactured. That is why we call them “Field Programmable.” They are configured with the help of hardware description language (HDL). It is similar to that used in application-specific integrated design (ASIC).

Then, how to use FPGA? You need FPGA boards. What are the FPGA boards? You must know about the printed circuit board or PCB, a chip that connects and supports all electronic components on it. Seeing an FPGA as an electronic component, when a board has this component, it is an FPGA board.

Easy, right? But, FPGA is never easy. You need to know something, like, how to design your FPGA board, and hiring who to manufacture your FPGA board.

Tips for Designing Your Own FPGA Board

If you need some modifications to the FPGA board, or you want to add extra hardware to it for your project, you need to design your own FPGA board to replace the basic test setup.

Some Dos of FPGA Design

  • Keep your schematic design as simple as possible keeping a layman in mind.
  • Emphasize attaching the clocks to the right pins in your schematic.
  • Be keen on the FPGA configuration design. If you have any doubts, take out extra signal buttons or LEDs.
  • Attention should be paid to the layer stacks and the thickness of copper wires for components of various pitches.
  • Any uncommitted FPGA pins should be brought out to the header. If there is any issue, these pins provide a good diagnostic tool for probing signals in the FPGA board.
  • The power supply should be designed early. It’s better to start by placing the small caps under the FPGA or near the pins. The larger caps should be placed outside the FPGA. And then the whole power supply circuit should be designed and placed where expected.
  • Communicate the layout with the PCB manufacturer early especially in case of impedance controlled routing. It’s a good idea to ask for a layer stack up for the required layer count. It makes it easier to route high-speed signals if you have defined the trace width earlier.

Some Don’ts of FPGA Design

  • Do not remove any bypass capacitors.
  • Do not try to reduce the PCB layers.
  • The BGA package is not as easy to work with as is TQFP or TQFN. Reworking on a BGA package is nearly impossible.

Some Notes of FPGA Design

1. One of the tricky parts is the power supply.

If there is a change in the firmware, the power ratings also change.

So it is a good idea to plan some supply current margin.

Some extra available current means no harm, but a shortage of current may lead to abnormal system behavior.

2. Some interfaces need clear master documentation for the interface between the top-level pins of the FPGA and the rest of the board, and at the connector interface among the boards.

At these places the pin locations, if internal or external net names get swapped or mismatched, this may lead to a failed PCB design.

3. An interface table is used to keep the interface in control and error-free.

This table should be set to the fabrication unit along with the copy of schematics, FPGA pins, and pad reports.

Who Can Well Manufacture Your FPGA Boards

FPGA is complex, so is the FPGA board. That’s why you need to find an advanced PCB manufacturer.

PCBONLINE, founded in 1999, is good at advanced circuits. For an FPGA board design, you can’t make sure that it is completely correct. But you can get 100% fantastic FPGA boards at PCBONLINE. Their experts will review your Gerber, BOM, and other documents before fabrication carefully, and every detail is fully considered to save your budget to the highest degree.

Here are reasons to hire PCBONLINE to manufacture your FPGA boards:

  • Our technology-oriented team is able to manufacture FPGA boards perfectly.
  • We have 100+ in-house R&D engineers to read and check your documents of the FPGA board when you send them online.
  • PCBONLINE supports PCB prototyping to avoid your economic loss in case your design has anything wrong.
  • First article inspection is operated when assembling your FPGA boards.
  • A free DFM/DFT/DFX report is provided.
  • PCBONLINE, also an independent hybrid electronics distributor, provides FPGAs for assembly.

PCBONLINE’s capability:

  • Layer: 1 ~ 42
  • Laminate: normal Tg/high-Tg/lead-free/halogen-free
  • Surface finishing: OSP/HASL/LF HASL/immersion ENIG/immersion tin/immersion silver
  • Board thickness: 0.15 ~ 3.2 mm
  • Max board size: 500 × 580 mm
  • Copper thickness: (inner finish copper) 1-4oz, (outer finish copper) 1-7oz
  • Min. line width/spacing: 0.0635 mm/0.0635 mm
  • Min. CNC drilling size: 0.15 mm
  • Min. laser drilling size: 0.075 mm
  • HDI stack up: 1+N+1, 2+N+2, 3+N+3

An FPGA board is basically an FPGA mounted on a PCB. The whole assembly of FPGA and PCB is called the FPGA development board or kit. You can order FPGA board manufacturing and assembly and track production status online.

Register and you can get $100 off coupons for your order immediately.

Why You Can Program and Reprogram FPGA

FPGA circuit board

FPGA is programmable because it is made up of an array of logic blocks that are programmable.

These blocks are connected through a hierarchy of interconnects that are reconfigurable and hence allow the blocks to be connected.

This is analogous to many logic gates that can be wired in multiple configurations.

The logical blocks of FPGA can be configured in multiple ways so that they can perform complex functions or simple logic gates like XOR and AND etc.

Most of the FPGA logic blocks also have memory.0 elements like flip flops or complete memory blocks.

Then why FPGA is reprogrammable?

The FPGAs can be reprogrammed for the implementation of a different logic function. It allows reconfigurable computing which is flexible.

The FPGAs have the ability to start the development of system software along with the hardware, which makes them suitable for use in embedded systems development.

The concurrent development of hardware and software enables the simulations of system performance at a very early phase.

It allows multiple system partitioning trials and iterations before finalizing the final system architecture.

FPGA Architecture

The basic FPGA architecture is made up of thousands of basic elements called configurable logic blocks (CLBs).

The CLBs are enclosed by a set of programmable interconnects known as the fabrics.

They route the signals between CLBs, I/O blocks help in the interfacing of FPGAs and other external devices.

FPGAs have a lookup table.

The look-up table stores a group of logical outputs for all possible combinations of inputs.

Lookup tables with four to six inputs are used mostly.

Standard logic functions like full adders, flip flops, and multiplexers are commonly used.

The arrangement and number of components in any CLBs vary with respect to the device.

The current generation of FPGAs consists of complex CLBs that are capable of multiple operations with a single block only.

The CLBs can also combine complex operations like registers, multipliers, counters, and some DSP functions.

Example of FPGAs

The entry-level FPGAs focus on low logic density, less power consumption, and lower complexity.

The higher-function devices include functional blocks that are devoted to exact functions.

Examples of these blocks include high speed serializes, phase-locked loops, Ethernet MACs, high-speed transceivers, and PCI Express controllers.

These blocks can be implemented using the CLBs or can be developed as independent circuits.

The high-level FPGAs family consists of the complex system on Chip parts.

They integrate the hard IP, FPGA architecture, and a CPU core in a single component.

The SoC FPGA provides a lower power, higher integration, smaller broad size, and higher-bandwidth communication among the core and blocks.

Benefits of using FPGAs

The programming of FPGAs is more complex than other microcontrollers. They also require more power.

But there are numerous advantages of these boards that outweigh these shortcomings of FPGAs.

  • Flexibility: unlike ASICs, where the hardware has fixed functionalities, FPGAs have a flexible and reconfigurable computing function. It helps reprogram and modify the device to implement a new logic function. A developer can make changes in the circuit without additional costs.
  • Security: there is a lesser risk of malicious alterations in the manufacturing or programming processes.
  • Performance: the FPGAs come with an off-load and acceleration functionality for the CPU, which improves the system’s performance. The speeds of data flow and processing are also faster than microcontrollers.
  • Efficiency: multiple input channels of information can be processed or controlled at a time, so parallel execution can be carried out, which improves efficiency. Because the data is processed only when there is a change in values, FPGAs spend less energy.
  • Time to market: FPGAs are suitable for prototyping applications. As the processes are parallel, the development steps can be carried out concurrently.
  • Latency: the FPGAs can compute anything in a very short time of around one microsecond as compared to very low latencies of CPUs of around 50 microseconds.
  • Connectivity: FPGAs can be connected directly to the inputs and offer high bandwidths. The data sources are also connected directly to the boards.
Applications of FPGA Boards:

FPGA board

The applications of FPGA boards are vast and increasing with the development of technology.

The FPGA boards are well-positioned for taking advantage of exciting new opportunities, like machine learning, AI, HPC, and hardware acceleration.

A good application is a high-speed search because FPGA boards adapt to the changes needed for new algorithms.

If a change is required, the design of FPGA is repurposed for running the simulation in the HPC applications.

Bing deployed FPGA boards to accelerate the performance of certain parts of its algorithms, and Microsoft uses them in its data centers.

The highly customizable SoCs find their applications in hardware startups like Networking, security, and data centers.

The FPGA boards are also used in signal processing applications like muxing/de-muxing at wireless network base stations, for they have a good amount of internal memory and multipliers.

They are used in loop testing of hardware/software or in ASIC emulation as well.

So many applications of FPGA boards.

To make it shorter, the generic areas of FPGA applications include:

  • Automation
  • Solar energy
  • Embedded vision
  • IoT
  • Cryptography
  • Aerospace and defense
  • Emulation of computer hardware
  • Signal processing
  • Scientific instruments
  • Broadcast
  • Data mining
  • Wireless communication

The FPGA market is growing at a very good pace. It is expected to hit 10 billion in 2023 as reported by industry researchers of markets.

Make your own FPGA board?

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History of FPGA

FPGAs were originally started as a competitor to CPLD for the implementation of glue logics for PCBs.

But with their evolution, their size, speed, and capabilities increased.

Therefore they took over more and more functions and now have become full systems-on-chip.

The FPGAs find their roots in early devices like PROMs (programmable logic memories) and PLDs (Programmable logic devices).

PROMs and PLDs could be programmed at the factory or in the field. They used fuse technologies and could not be modified once programmed.

Whereas the FPGAs store their configuration information in a medium that is re-programmable like flash memory or static RAM (SRAM).

In the late 1990s, dedicated multipliers were added to the FPGA architectures.

With this development, FPGAs started finding applications in digital signal processing applications.

Conclusion

This blog gives comprehensive research on FPGAs and FPGA boards.

The FPGA boards are providing the capability to create flexible and adaptive hardware. They enable future research without using the typical circuit designs, whose functionality cannot be updated once they are manufactured.

If you design your own FPGA board, ask PCBONLINE to manufacture and assemble it. You can always expect wonderful quality and considerate service once you work with them.