FPGA Description

FPGAs (Field-Programmable Gate Arrays) have established themselves as one of the most versatile technologies in digital electronics over the last decades. They offer a unique blend of flexibility (e.g. “field updates”), high performance and parallel processing, which sets them apart from traditional microprocessors and ASICs (Application-Specific Integrated Circuits). But what exactly are FPGAs, how do they work and what are they used for?

What is an FPGA and what are the advantages of Efinix FPGAs?

An FPGA is an integrated circuit whose functionality can be programmed by the user (in the field) after production. This programmability distinguishes FPGAs from conventional standard ICs, whose function is already defined during production. FPGAs consist of several hundred, up to currently several million logic elements that can be flexibly interconnected to implement complex digital circuits.

An FPGA essentially consists of:

1. Logic blocks
   performing logical and arithmetic operations. They consist of configurable logic units (lookup tables, LUTs) and flip-flops. The LUT4 has established itself as a measurement unit for the size / compute power of an FPGA, even if the basic cell is often a LUT6. A LUT is any input digital function. Usually one or more LUTs are combined with a flip-flop (a 1-bit memory cell). Often, circuits for fast arithmetic operations (e.g. fast carry chain adders) are also present in the logic blocks. The size of the FPGA is often coded in kLUT in the component designation. For example, a Trion T20 FPGA from Efinix has approximately 20 kLUT (19.728 LUT4 to be precise) and the same number of flip-flops.
2. Routing ressources
   They connect the logic blocks with each other and enable a flexible circuit arrangement. With almost all manufacturers, logic and routing are strictly separated. If one of the two resources is insufficient for a given design, you have to switch to the next largest FPGA in the component family. In most cases, there are not enough routing resources available and the design can be accommodated in purely computational terms, but it can no longer be routed or the desired timing cannot be achieved.
   This is exactly where Efinix comes in with its Quantum technology: the basic cell of the FPGA (XLR-Cell = eXchangable Logic and Routing Cell) can become either a LE (Logic Element) or a Routing Matrix at compile time. This means that the available resources can be utilized very efficiently.
   
   

   

3. I/O blocks
   Ensure communication with the outside world by forwarding digital signals from and to external devices. Modern FPGAs have IOs optimized for speed (HSIOs = High Speed IOs) as well as so-called HVIOs (High Voltage IOs). In the context of modern FPGAs, “high voltage” refers to 3.3V-capable IOs. In addition, there are usually special IOs for certain interfaces (such as MIPI for camera and video applications), as well as fast serial interfaces (such as PCIe or 10 GE).

   

4. ASIC blocks
   Certain circuits cannot be implemented with the basic cells of FPGAs or would then be too large and too power-hungry. This is why almost all modern FPGAs have built-in ASIC blocks such as PLLs, RAM, DSP blocks and even processors. PLLs (phase-locked loops) are for generating “arbitrary” clocks and provide the “pulse beat” of digital systems. Memory blocks (RAM) allow the intermediate storage and processing of data. DSP blocks enable fast multiplications for digital filter functions or neural networks. When it comes to processors, many manufacturers now rely on RISC-V, an “open architecture”. In conjunction with FPGAs, the instruction set can be expanded as needed and so-called “hot loops” can be accelerated in hardware in the FPGA.

What does an FPGA development flow look like?

The functionality of an FPGA is based on the programming of its internal structure. Almost all FPGA manufacturers use SRAM cells for configuration, which is a volatile technology. This means that almost all FPGAs require an external or internal, non-volatile configuration memory.

The circuits are usually designed using a hardware description language (HDL) such as VHDL (= VLSI HDL, where VLSI stands for Very Large Scale Integration) or Verilog. Recently, there have also been description languages such as SystemC, SystemVerilog etc., which enable circuit descriptions at a higher level of abstraction.

The development process (for Efinix FPGAs it is called Efinity) comprises the following steps:

1. Circuit design
   Developers specify the desired functionality with an HDL.
2. Synthesis
   The HDL code is translated into a technology-specific netlist of logic elements (in Edif format). This step is accomplished by a so-called synthesis tool. In the Efinity flow, the synthesis tool is aware of the XLR cell and efficiently utilizes its flexibility.
3. Place & Route
   The P&R software assigns the logic elements of the netlist to the physical resources of the FPGA and determines how they are connected.
4. Programming
   The configured logic (= bitstream) is loaded into the FPGA.

The big advantage is that the FPGA can be reprogrammed at any time to meet changing requirements.

Areas of application for FPGAs

FPGAs are used in a variety of applications that require high performance, parallel processing and flexibility:

1. Telecommunications
   In mobile phone base stations, networks and signal processing systems, FPGAs offer fast processing of data streams and protocols. Protocols or standards that have not yet been finalized can be flexibly implemented in FPGAs and updated through field updates.
2. Image and Video processing
   Accelerate algorithms for image processing, for example in cameras, surveillance systems and medical devices. Nowadays, many cameras are “intelligent” (see point 3).
3. Artificial Intelligence (AI)
   FPGAs can efficiently execute neural networks. They do not achieve the performance of GPUs that have been optimized precisely for this task, but offer greater flexibility and adaptability.
4. Industrial and Medical applications
   FPGAs are known for their longevity and are therefore popular in these markets, which demand long product life cycles.
5. Automotive industry
   Among others FPGAs are used in driver assistance systems (ADAS), lidar and radar systems. FPGA manufacturers usually offer a subset of their FPGAs with AEC Q100 certification.
6. Space and Aerospace
   There are special, radiation-resistant FPGAs for mission-critical “deep space” applications. In addition, industrial FPGAs are used in the so-called “New Space” market. In aviation, DO-254 certification is still required and the choice of FPGA depends on the Design Assurance Level (for instance DAL-A). These markets also value the longevity of FPGAs.

Advantages and challenges

Advantages:

• Flexibility
  FPGAs can be easily updated or customized.
• Parallel processing
  They allow the simultaneous execution of many tasks. For tasks that require parallel processing, they offer higher speed than processors (unless they have already been optimized for this particular task).

Challenges:

• Cost
  FPGAs are usually more expensive than standard ICs, especially in large quantities. Thanks to the QuantumTM technology, Efinix FPGAs can use the available resources efficiently and flexibly. As a result, die area can be saved and fewer routing resources (metal layers) are required. Both have a favorable effect on cost.
• Power consumption
  FPGAs tend to have a higher power consumption than ASICs. The QuantumTM technology offers advantages here as well, since small dies and efficient routing result in comparatively low dynamic power dissipation. In modern FPGAs, the dynamic power dissipation is usually the largest part of the total power dissipation. As a result battery-operated systems can be used for longer and heat can be dissipated more easily. Electronics that can be operated cooler have a longer service life, allow a higher ambient temperature. Also sensitive analog sensors are not disturbed unnecessary heat.
• Complexity
  FPGA development requires special know-how and tools.

TRS-STAR is happy to support you in your FPGA projects with a partner network. Our partners have decades of design experience and are usually among the first users of new FPGA families.

Future prospects

With the progress in semiconductor technology and the growing demand for flexible solutions, the importance of FPGAs will continue to increase. This can also be seen in the development of the global FPGA market and the forecasts for this market. As we all know, figures don't lie. Especially in areas such as edge computing, autonomous driving and 5G networks, the ability to quickly implement customized hardware solutions will play a crucial role.
FPGAs provide a bridge between general computing power and specialized hardware and are an indispensable tool for engineers and developers looking for innovative and powerful solutions.