What is Field Programmable Gate Array(FPGA)?

Ⅰ. What is an FPGA

A semi-custom digital integrated circuit called an FPGA  (Field Programmable Gate Array). Due to their great flexibility, short development cycle, and high processing performance, FPGAs are widely utilized in communication, image processing, medical, and other industries (parallel). FPGA  s are becoming more common in sectors like artificial intelligence, 5G, and autonomous driving as technology improves.

FPGA is a product that was developed from programmable devices like the  PAL, GAL, and CPLD. In the field of application-specific integrated circuits (ASIC), it appears as a semi-custom circuit that not only solves the drawbacks of bespoke circuits but also overcomes the limitations of the restricted number of original programmable devices gate circuits.

Breadboard to build digital clock circuit

Figure. 1

The circuit is a digital clock with a crystal oscillator, buzzer, digital tube, and different 74 series tiny chips, as shown in the diagram. These little devices can perform functions that are comparable to multiple logic gates. If you make it yourself, you'll quickly discover that it's a difficult circuit to construct. Connect one line at a time, and review the schematic design frequently for fear of constructing the incorrect line, or your mentality collapsing.

That's all there is to it when it comes to making a simple digital clock. If we want to implement more complex functions, we will have difficulty because we will need to use dozens or hundreds of such dedicated small chips to complete, which will complicate the layout and wiring of the circuit board. It will also have a significant impact on the overall system's performance, and the built circuit is bulky, unsightly, and impractical, so this method is clearly unacceptable.

To change this predicament, everyone devised a solution: using application-specific integrated circuits (ASICs), we can hand over the particular needs to be implemented to  ASIC  makers, who would then create an application-specific integrated circuit chip to solve the problem.

For example, we can give the  ASIC manufacturer the digital clock's functional requirements, and the ASIC manufacturer will develop an application-specific integrated circuit chip based on the digital clock's functional needs. The function of our digital clock circuit is actually completed by this little device. Although this strategy is effective, it also has a number of drawbacks. The generation cycle, for example, is long, the chip is difficult to test, and the chip's internal circuit cannot be altered. As a result, individuals began to search continually to see whether there was any way for me to not only realize the function well, but also to fix the custom circuit's insufficiency.

As a result, FPGA  was born. It was created in 1985 by  Ross Freeman , one of  Xilinx's founders. It's a type of PLD (programmable logic device) (Programmable Logic Device).

Xilinx A7 series FPGA chips

Figure. 2

Xilinx invented the first FPGA  chip, the XC2064, in the genuine sense, roughly 20 years after  Moore's Law, however, once FPGA  was released, the ensuing development speed was faster than most people expected.

Before leaving the manufacturer, we need to know that the function of a specific ASIC custom integrated circuit chip has been fixed. As an example, consider the digital clock shown above. If I get a brand new digital clock chip right now, all I have to do now is look at it. The manufacturer handed me the data sheet so I could look at it and see how it works. I figured I'd just power it up and set up it to function.

It has a fixed function; it can only run a digital clock, and I have no idea what its internal circuit is. The FPGA.  on the other hand is distinct since it is straightforward to use but lacks versatility. It serves no purpose at the time, hence it can be described as a blank piece of paper. This piece of white paper is yours to do whatever you want with. If you want it to perform the function of a digital clock, that is not an issue. The logic of the digital clock can be written in a specific editing language, such as  Verilog,  VHDL, or other hardware description languages, and then downloaded to the  FPGA's internal memory. To complete the function of the digital clock, it will generate a digital clock circuit. You can delete the internal software at any moment or use a new design to overwrite the original design if you don't want this function. In theory, we should be able to produce whatever function we want using FPGA,   FPGA has been increasingly recognized by the market in recent years as a result of its powerful editability, and its scope of use will continue to expand in the future.

Ⅱ. Where we use FPGA?

The fields in which FPGAs can be applied can be roughly divided into six categories:

1) Communication field

The omnipotent application of FPGA in the sphere of communication can be asserted. Due to the internal structure of the FPGA.  it is very easy to realize the distributed algorithm structure, which is particularly useful for realizing high-speed digital signal processing in wireless communication. Because many functional modules in a wireless communication system require a significant number of filtering operations, these filtering functions frequently necessitate a large number of multiplying and accumulating operations. An FPGA can efficiently implement these multiply and accumulate operations by developing a distributed arithmetic structure. Xilinx's FPGA.  in particular, integrates a large number of communication-related resources, including baseband processing (channel card), interface and connection operations, and  RF  (radio frequency card) in three categories:

(1) Baseband processing resources

Channel codec (LDPC, Turbo, convolutional code, and RS code codec techniques) and synchronization algorithm implementation are the major components of baseband processing (WCDMA system cell search, etc.).

(2) Interface and connection resources

The exterior high-speed communication interface (PCI Express, Ethernet MAC, high-speed AD/DA interface) of the wireless base station, as well as the related internal backplane protocols, are primarily realized via the interface and connection functions (OBSAI,  CPRI,  EMIF, LinkPort).

(3)RF Application Resources

Modulation/demodulation, up/down conversion (WiMAX,  WCDMA,  TD-SCDMA, single-channel, multi-channel DDC/DUC for CDMA2000 systems), peak clipping (PC-CFR), and distortion (Predistortion) are the most common  RF applications.

Overall, as long as you master FPGA.  you will be able to demonstrate your communication abilities.

2) The field of digital signal processing

FPGA is also unbeatable in the field of digital signal processing, owing to its high-speed parallel processing capability. The most significant advantage of FPGA is its parallel processing mechanism, which employs parallel architecture to accomplish digital signal processing functions. Because of this parallel mechanism, FPGA is particularly well suited to performing repetitive digital signal processing tasks such as FIR digital filtering. FPGA performance greatly outperforms the serial execution architecture of general-purpose DSP processors for high-speed parallel digital signal processing workloads. One is that, unlike traditional DSP, the voltage and driving capability of its interface can be programmable and configured. This is in contrast to traditional DSP, which is controlled by the instruction set because the instruction set's clock cycle is limited and cannot handle very high-speed signals. It's difficult to deal with class signals. As a result, FPGA has a wide range of applications in the field of digital signal processing.

3) Video image processing field

With the passage of time, people's expectations for visual stability, clarity, brightness, and color have risen steadily, similar to how standard definition (SD) gradually evolved into high definition (HD) and now Blu-ray quality. Image. This increases the amount of data that the processing chip must process in real time, while simultaneously increasing the complexity of the picture compression method, to the point where the simple use of ASSP or DSP can no longer handle such a significant volume of data processing. The benefits of FPGA are being emphasized at this moment. It has the ability to digest data more quickly. As a result, in the field of image processing, FPGA is becoming increasingly popular in the market after taking into account all costs.

4) High-speed interface design field

In reality, after seeing FPGA's capabilities in communication and digital signal processing, I believe everyone should have realized that FPGA must also have a place in high-speed interface design. Its distinctive benefits in the field of high-speed interface design are determined by its high-speed processing capability and hundreds or thousands of  IOs.

For example, I may need to interact with data on a computer, send collected data to a computer for processing, or send processed results to a computer for display. ISA,  PCI,   PCI Express, PS/2,  USB, and more interfaces exist between the PC and the external system. The typical way is to use the matching interface chip, such as a PCI interface chip, for the corresponding interface. I require numerous such interface chips when I need a lot of interfaces, which will surely complicate our hardware peripherals and raise the volume. It is large and inconvenient, but if you use FPGA, the benefit will be immediately apparent, because different interface logic can be implemented inside FPGA, so there is no need for as many interface chips as before. This, combined with the use of DDR memory, will make our interface Data processing more convenient.

5) Artificial intelligence field

If you prefer to keep up with technology news, you've probably heard a lot about 5G communication and artificial intelligence recently. Without realizing it, the twenty-first century has slipped into the year 2020. Artificial intelligence has advanced rapidly over the last 20 years, and the smooth growth of 5G has made it even more powerful. It is clear that the world of artificial intelligence will be the world of the future.

FPGAs are also widely used in the front-end part of artificial intelligence systems, such as autonomous driving, which necessitates the collection of a variety of traffic signals, such as driving routes, traffic lights, roadblocks, and driving speeds, and the use of multiple sensors to synthesize these signals. For driver and fusion processing, FPGAs can be employed. FPGAs are also useful for the front-end information processing of artificial intelligence systems, as some intelligent robots require to gather and process photos or interpret sound inputs, which can be done using FPGAs.

6)  IC verification field

When you hear the word IC, you might think it is something incredibly advanced that is beyond reach for ordinary people, and that  IC design is something only gods can do. Although the bar for IC design is unquestionably high, we don't need to go too far. To put it another way, we can relate it to  PCB  design. Building components one by one on a printed circuit board is known as PCB. One MOS tube and PN section are used to produce a circuit combined with a specific function on the silicon substrate, one macro, and one micro, and IC design is to use one MOS tube and PN section to build a circuit combined with a specific function on the silicon substrate. If the  PCB design is abandoned and then revised, the loss will be little, but if the IC design is abandoned and then redesigned, the loss will be significant. Gold is not blown when the machine is turned on. The photoresist is costly, and opening molds using photolithography is costly. Hundreds of thousands of other processes, such as people, material resources, machine loss, and machine maintenance, are also involved. Absolutely It's a heartbreaking loss, thus IC design must accentuate the first edition's success. To assure the success of the IC version, significant simulation testing and FPGA verification are required. Simulation verification, comparable to  ModelSim /VCS software, entails running simulation software on a server for testing; FPGA verification entails transplanting IC code to the FPGA and using FPGA synthesis. The tool is synthesized, put, and routed to generate a bit file, which is then downloaded and verified on the FPGA verification board. We can also partition complex ICs into numerous partial functions to verify separately, and each functional module is installed on an  FPGA,  FPGA-generated circuits are remarkably similar to real IC chips. This makes it much easier for our IC creators to check their own designs.

Ⅲ.  FPGA manufacturer

Two giants:  Xilinx and  Altera.

Ziguang Tongchuang, Jingwei Yager, Gowin Semiconductor, Shanghai Anlu, Xi'an Zhiduoji, and others are a group of younger brothers. In terms of product performance, power consumption, and functionality, domestic FPGA manufacturers lag behind global top manufacturers.

ZYNQ

ZYNQ = FPGA +  ARM  core, you can customize the circuit yourself, and you can also do ordinary embedded development.

Xilinx introduced the Zynq-7000 series, an all-programmable system-on-chip that consists of two parts: PS (Processing System, processor system) and PL (Programmable Logic, programmable logic). The Zynq SoC combines an  ARM dual-core cortex-A9 processor with a Xilinx 7 series FPGA fabric, providing it not only the power, performance, and compatibility of an ASIC, but also the flexibility and programmability of FPGA hardware.

PYNQ:  Python  Productivity for Zynq (Python + ZYNQ) is an open-source framework created by Xilinx that uses the  Python language and libraries to allow designers to quickly build high-performance Embedded applications using programmable logic and microprocessors in Zynq.

Replenish

PLD: Programmable Logic Device, programmable logic device.

Figure. 3