What Is FPGA (Field-Programmable Gate Array)? Meaning, Working, and Uses

A field programmable gate array is an integrated circuit that made of semiconductor material which can be re-programmed or re-configured by the user after purchased instead of the original equipment manufacturer (OEM) alone. In this article we explains , how FPGAs are work and their applications in various industrial areas.

What Is FPGA (Field-Programmable Gate Array)?

A field programmable gate array is an integrated circuit that made of semiconductor material which can be re-programmed or re-configured by the user after purchased instead of the original equipment manufacturer (OEM) alone. In this article we explains , how FPGAs are work and their applications in various industrial areas.

FPGAs are constructed from a grid of configurable logic blocks (CLBs) coupled with programming inter-connects, field programmable gate arrays (FPGAs) are semiconductor devices. After manufacturing, FPGAs devices can be re-programmed for specific functionality and application needs for industries and different projects.

FPGAs are sets apart from Application Specific Integrated Circuits (ASICs) because of this feature. The latter is explicitly made for a given goal, which cannot change later. Although One time programmable (OTP) FPGAs are used as an option, Static Random Access Memory (SRAM) based models are most common and it also allows for re-programming as the design changes with time.

Input or output pads, re-programmable interconnect, and programming logic blocks combined make up a field-programmable gate array FPGA. Flip-flops/memory blocks may be used as memory components in the logic blocks of a field-programmable gate array FPGA. These logic blocks can be used to carry out simple to complicated computational operations.

Field-programmable gate arrays FPGA and programmable read only memory chips share many similarities. FPGA can accommodate several thousand gates, unlike programmable read only memory chips, which are only restricted to a few hundred. Field-programmable gate arrays (FPGA) are re-programmable, as opposed to ASICs, which are developed for specialized jobs.

Computer users can customize the capabilities of microprocessors to suit particular individual demands using a field-programmable gate array (FPGA). Engineers use FPGAs to create specialized integrated circuits for many purposes. Field-programmable gate arrays' (FPGA) life cycle is more predictable due to absence of wafer capabilities.

Potential respins, a shorter time to market than competing alternatives, and an easy design cycle are further advantages. Numerous sectors and markets, including wireless communications, data centres, the automotive, medical, and aerospace sectors, use FPGAs.

The fact that the chip used in the FPGA is completely programmable and re-programmable is a considerable benefit. In this way it turns into a sizable logic circuit, one setup following a design, but users can also update that to make adjustments as per need. In other words, if a circuit card/board is created and FPGA is a component of that circuit, then the FPGA is programmed during the creation process but can subsequently be re-programmed to reflect any modifications.

Its name refers to the possibility of field programming. The first FPGAs were released in the early 1980s, but their popularity didn't really take off until the late 1990s. They weren't well-known outside of a few companies like Altera, Xilinx, and TI.

Then the millennium bug hit, and FPGAs began to proliferate. Businesses started looking more closely at them as a replacement for ASICs (application-specific integrated circuits), which had been used to develop systems that were too complex for standard CPUs or GPUs.

Field programmable gate arrays are still a hot topic in technology today because they allow users to make goods at lower costs and with less power consumption. They are also useful in other applications, such as networking and networking security. This is a significant improvement over traditional microcontrollers, which cannot support larger designs.

The 8051 microcontrollers, for instance, used the Harvard design and the CISC instruction set. These built-in instruction sets are absent from FPGAs, providing the designer more flexibility. FPGAs are increasingly being used in consumer electronics, while being typically associated with high-end computing.

In advanced graphics cards, a field-programmable gate array chip already has numerous features. Despite this, they are less expensive and power-hungry than traditional video cards. They also offer a much higher throughput and support multiple concurrent streams. As a result, game consoles are using FPGA-based graphics cards more commonly.

Just two of the numerous programming languages used with FPGAs are Verilog and VHDL. Verilog, a language for describing hardware, was developed in 1984. It is a design standard for FPGAs and can be used to create any form of circuit required for a system.

VHDL is another popular language for programming FPGAs that uses the state machine concept. It differs from Verilog in that it has more features, like as data types and signal names, which simplify the design of complex circuits and raise their efficiency. The language and syntax used in FPGA programming are specified.

How Does FPGA Work?

Every FPGA manufacturer has a unique specification for its architecture. The key components, principles, and functionalities including the following:

1. Configurable logic blocks

A CLB is the fundamental building block of a field programmable gate array. It is a logic cell that may be configured or programmed to perform certain functions. and these building blocks are connected to the connecting block. These elements consist of transistor pairs, carry and control logic, and look-up tables (LUTs). They carry out the design-required logic processes.

A CLB can be made using logic-based multiplexers, also known as LUTs. The D flip-flop, look-up table, and 2:1 multiplexer make up the block in LUT-based logic. Flip-flops are used as storage-related components. The appropriate output is chosen by the multiplexer. Each CLB contains a particular number of slices. Columns and pairs are used to arrange the slices.

2. Programmable interconnects

The field programmable gate arrays' unique linkages between logic cells that are situated in various logic blocks are all included here. The interconnect is frequently implemented using switch boxes that comprise a number of fundamental semiconductor switches. The routing path for these programmable logic blocks is provided by these electrically programmable links.

Along routing paths, wire segments of various lengths can be identified and connected by electrically programmed switches. The number of components utilised to create routing paths affects the density of a field programmable gate array. A field programmable gate array's outputs or input pads can be connected to any other cell or pad in the circuit using programmable interconnect points, which are an essential component of every field programmable gate array.

3. Programmable routing

Because it often comprises more than 50% of the fabric area and the significant route delay of applications, programmable routing is essential. Prefabricated wire segments and pre-programmed switches make up programmable routing. Any function block output may be connected to any input by selecting the appropriate switches in the configuration. Field-programmable gate array routing architecture can be divided into two categories.

Hierarchical field programmable gate arrays were inspired by the fact that designs are intrinsically hierarchical; higher-level components instantiate lower-level modules and link signals across them. Because communication occurs more frequently between modules that are close to one another in the design hierarchy, hierarchical field programmable gate arrays can build these connections utilising short wires to connect discrete parts of a chip. the density of the FPGA and

4. Programmable I/O blocks

To connect logic blocks with external components, interface pins are employed. The IOB (Input Output Block), a programmable input and output device used to fulfil the driving and matching needs for input/output signals under diverse electrical characteristics, serves as the interface between the field programmable gate array and external circuits. The routing architecture and CLBs are connected to the outside world by the I/O blocks.

Input/output blocks give programmable unidirectional or bidirectional connections between the package pins and the device's internal circuitry. Because earlier field programmable gate arrays lacked a CPU to run any software, implementing an application required building the circuit from scratch. As a result, an FPGA can be configured to be as basic as an OR gate or as complex as a multi-core processor.

5. On-chip memory

The first type of on-chip memory element in FPGA systems was the FFS, which was integrated into the logic blocks of the FPGA. Field programmable gate array logic was nevertheless employed in larger systems that almost always required memory to buffer and reuse data on the chip as its processing power increased. It became essential to have more dense on-chip storage since creating large RAMs made up of registers and LUTs is approximately 100 times less dense than creating an SRAM block.

Additionally, the amount of RAM needed by programmes running on field programmable gate arrays varies greatly.

6. Digital Signal Processing (DSP) blocks

The only dedicated arithmetic circuits utilised in commercial field programmable gate array systems prior to transportable chains were adders.

The necessity to include multipliers in the soft logic using LUTs and carry chains resulted in a substantial space and delay penalty. Designers created unique approaches to overcome the inefficiency of soft logic multiplier implementations since high-multiplier-density signal processing and communication applications for field programmable gate arrays account for a sizable portion of the market. Digital signal processing, or DSP, is the term used for this.

One method for developing effective finite impulse response (FIR) filter designs with LUT-based field programmable gate arrays is the multiplier-less distributed arithmetic technique. Due to their widespread use in field programmable gate array designs across important application domains and their reduced size, latency, and power consumption when implemented in soft logic, multipliers are a top contender for hardening as specialised circuits in FPGA systems.

7. System-level interconnect

A few of the factors contributing to the FPGA's increasing capacity and bandwidth are the development of DDR memory and Ethernet. It is difficult to control data flow between these high-frequency ports and the expanding soft fabric. In the past, this system-level link was created by configuring particular FPGA logic and routing components to create soft buses that carry out pipelining, multiplexing, and wiring between the required endpoints.

Wider (soft) buses, which operate at frequencies higher than those of the field-programmable gate array fabric, are the only way to match the bandwidth of these external interfaces. Timing closure is difficult and frequently necessitates significant pipelining of the soft bus due to the extensive and physically lengthy buses, which increases resource consumption.

Applications of FPGAs

FPGAs are widely used in a variety of sectors, particularly in the industrial Internet of Things (IoT). Its primary application areas include

1. Case studies in the energy industry

Renewable energy sources like solar and wind power are becoming more and more common. In a smart electricity grid where laws are still being developed, they are dependable. For smart grids to function at their best, transmission and distribution (T&D) substations in particular require efficient power networks. Automation calls for technology that continuously regulates, safeguards, and monitors the grid in order to manage peak demand loads more effectively. Smart grids' performance and scalability can be increased while consuming less power thanks to FPGAs.

2. Designing ASICs using FPGAs 

The architecture of such a circuit must first be made. The prototype is then built and tested using an FPGA; mistakes can be fixed using this technique. An ASIC project is created as soon as the prototype meets expectations. As designing an integrated circuit can be a labor-intensive and challenging process, this allows you to save time.

A single FPGA can be used to develop multiple revisions of the same project, which also saves money. It's crucial to keep in mind that the present Tensor Processing Units (TPUs) or cryptocurrency miners were first created as FPGAs and then only then were they manufactured.

3. Improvements in automotive experiences

Solutions for in-car comfort, convenience, and entertainment using automotive silicon and IP. Vehicle original equipment manufacturers (OEMs) and suppliers can create cutting-edge safety applications like cruise control, blind spot warning, and collision avoidance using Microsemi FPGAs.

Vendors of FPGAs also offer dependability characteristics like error-corrected memory and low static power along with cybersecurity features like information assurance, anti-tampering, and hardware security. FPGA-based storage can offer low static power because of their negligible leakage and capacity for low-power situations.

4. Supporting real-time systems

FPGAs are used in real-time systems where response speed is crucial. It's impossible to forecast with any degree of accuracy when you'll hear back after the trigger fires with typical CPUs because response times are unpredictable. To keep reaction times within set parameters, real-time operating systems are used.

This falls short in circumstances where a prompt response is necessary. Systems must deal with this problem and provide a constant response time by implementing the requested approach in an FPGA using combinational or sequential circuits. A real-time system like this can be modified and put into operation using an FPGA once it has been constructed.

5. Aerospace and defence use cases

Industrial manufacturing businesses produce rad-hard and rad-tolerant FPGAs, which are frequently space-grade, to match the performance, reliability, and lifetime requirements of harsh environments while providing more flexibility than is feasible with standard ASIC implementations. Rad-hard reconfigurable FPGAs are appropriate for space systems that require a lot of processing.

6. Usage in communications and software-defined networks (SDN)

To be employed in a complicated, real-time setting, software-defined networks (SDN) and other algorithms like the Fast Fourier transform (FFT) must be loaded into an FPGA. A radio's conventional parts include an antenna for receiving and sending signals as well as network gear for signal processing, such as filtering and frequency adjustment.

This hardware was unable to substantially change the functions for which it was designed. In the modern era, a sizable piece of this functionality has been transferred to an electronic device, often an FPGA. An antenna, ADC, and DAC converters are typically all that make up the analogue component.

7. FPGAs in data centres and cloud

The amount of data being collected and processed is increasing exponentially as a result of big data and the internet of things (IoT). There is a strong demand for low-latency, flexible, and secure computational power as a result of this, coupled with computational analysis of the same data using deep learning techniques of many tasks concurrently. The rising prices of space mean that adding more servers is not a viable solution.

The doors to the world of the data centre are being opened to FPGAs to a great extent because of their capacity to expedite processing, flexibility in design, and security that the hardware provides against software.

8. Computer vision systems

Computer vision systems are a common feature of current electronics. Examples of this include robots, video surveillance cameras, and other gadgets. In order for many of these devices to behave and interact with humans in a way that makes sense given their position, surroundings, and facial recognition capabilities, an FPGA-based system is frequently required. Many images must be processed in order to employ this function, with the majority of these operations being carried out in real-time in order to recognise objects, identify faces, etc.