Differences Between FPGA, ARM, ASIC, and SoC

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1. ASIC

ASIC, or Application-Specific Integrated Circuit, refers to integrated circuits designed and manufactured to meet the specific needs of a particular user and electronic system. Currently, using CPLD (Complex Programmable Logic Device) and FPGA (Field Programmable Gate Array) for ASIC design is one of the most popular methods. They share the common feature of being user-programmable on-site and supporting boundary-scan technology, but they each have their own characteristics in terms of integration, speed, and programming methods.

Currently, in the integrated circuit world, ASIC is considered a type of integrated circuit designed for specific purposes. It is designed and manufactured to meet the specific needs of a particular user and electronic system. The characteristics of ASIC include being tailored to specific user requirements, and when mass-produced, ASICs have advantages such as smaller size, lower power consumption, increased reliability, improved performance, enhanced confidentiality, and reduced costs compared to general-purpose integrated circuits.

Design Process

First, it is necessary to divide the internal functional modules of the ASIC so that each functional module achieves the corresponding function. The various functional modules are connected together to form the entire ASIC circuit. Second, based on the division of functional modules, hardware description language (HDL) is used to perform the logical design of the modules according to functional and interface requirements, forming Register Transfer Level (RTL) code. Third, based on the functional and timing requirements of the ASIC specification, test code or test stimuli are written using FPGA prototypes or software simulations to perform logical verification and ensure that the logical design fully meets the design requirements. Fourth, the RTL code is mapped to the corresponding process library using logic synthesis tools, layout and routing are performed, timing verification and convergence are completed, and layout data for production is generated.

2. SoC

SoC, or System on Chip, refers to a product that is a dedicated integrated circuit containing a complete system and all the content of embedded software.

SoC is an abbreviation for System on Chip, which literally translates to “chip-level system” and is usually referred to as “on-chip system”. Since it involves “Chip”, SoC also reflects the relationship and distinction between integrated circuits and chips, including the design of integrated circuits, system integration, chip design, production, packaging, testing, etc. Similar to the definition of “chip”, SoC emphasizes a whole. In the field of integrated circuits, it is defined as a system or product formed by combining multiple integrated circuits with specific functions on a single chip, which contains a complete hardware system and its embedded software.

This means that a single chip can complete the functions of an electronic system, whereas this system previously often required one or more circuit boards, as well as various electronic components, chips, and interconnections on the board working together to achieve. Earlier, we mentioned the integration of buildings to single-family houses when talking about integrated circuits, while SoC can be seen as the integration of towns to buildings; hotels, restaurants, shopping malls, supermarkets, hospitals, schools, bus stations, and numerous residences come together to form the functions of a small town, meeting people’s basic needs for food, housing, and transportation. SoC emphasizes the integration of processors (including CPU, DSP), memory, various interface control modules, and various interconnect buses, with typical representatives being mobile phone chips (see the introduction of the term “terminal chip”). SoC has not yet reached the level of achieving a traditional electronic product on a single chip; it can be said that SoC has only achieved the functionality of a small town and cannot yet achieve the functionality of a city.

3. FPGA devices are a type of semi-custom circuit within application-specific integrated circuits, which are programmable logic arrays capable of effectively solving the problem of insufficient gate count in existing devices. The basic structure of FPGA includes programmable input/output units, configurable logic blocks, digital clock management modules, embedded block RAM, routing resources, embedded dedicated hard cores, and lower-level embedded functional units. Due to the rich routing resources, reprogrammability, and high integration of FPGAs, they have been widely applied in the field of digital circuit design. The design process of FPGA includes algorithm design, code simulation, design, board debugging, where designers establish algorithm architectures based on actual needs, use EDA to establish design schemes or write design codes in HDL, ensure that design schemes meet actual requirements through code simulation, and finally perform board-level debugging, using configuration circuits to download relevant files to the FPGA chip and verify the actual operation effects.

Note: FPGA and most chips use the ARM architecture. Simply put, in a chip, ARM acts as the brain while the rest act as the body; ARM is the lowest-level design. There are many series within the ARM architecture.

Introduction to ARM Architecture

(1) ARM

ARM refers to embedded development boards that use the core chips from the British ARM (Advanced RISC Machines) company as CPUs, along with additional peripheral functions, to evaluate the functionality of the core chips and develop products for various technology companies.

The ARM microprocessor currently includes the following series, as well as other processors based on the ARM architecture from other manufacturers. Besides sharing the common characteristics of the ARM architecture, each series of ARM microprocessors has its own features and application fields.

– ARM7 series

– ARM9 series

– ARM9E series

– ARM10E series

– ARM11 series

– Cortex series

– SecurCore series

– OptimoDE Data Engines

– Intel’s Xscale

– Intel’s StrongARM ARM11 series

(2) Cortex series

The Cortex series has made breakthroughs in the field of 32-bit RISC CPU development, evolving its microprocessor architecture from v3 to the current v7. Cortex processors are based on the ARMv7 architecture and are divided into Cortex-M, Cortex-R, and Cortex-A categories. Due to differences in application fields, the technologies used in the Cortex processor series based on the v7 architecture also differ. Those based on v7A are referred to as the “Cortex-A series”. The high-performance Cortex-A15, scalable Cortex-A9, market-validated Cortex-A8 processor, as well as the efficient Cortex-A7 and Cortex-A5 processors all share the same architecture, thus possessing complete application compatibility, supporting both traditional ARM and Thumb instruction sets, as well as the new high-performance compact Thumb-2 instruction set.

1. Cortex-M series

The Cortex-M series can be further divided into Cortex-M0, Cortex-M0+, Cortex-M3, Cortex-M4;

2. Cortex-R series

The Cortex-R series is divided into Cortex-R4, Cortex-R5, Cortex-R7;

3. Cortex-A series

The Cortex-A series includes Cortex-A5, Cortex-A7, Cortex-A8, Cortex-A9, Cortex-A15, Cortex-A50, and so on, also corresponding to development boards such as Cortex-M0, Cortex-A5, Cortex-A8, Cortex-A9, Cortex-R4, etc.

(3) Semiconductor

Since ARM only provides ARM cores externally, major manufacturers develop and produce their own chips based on licensed ARM cores, forming a large family of embedded ARM CPUs. The vendors providing these core chips include Atmel, TI, Freescale, NXP, ST, and Samsung, among others.

Conclusion: FPGA uses the ARM architecture and is a programmable custom circuit, while ASIC is simply an integrated circuit that can run on FPGA, implementing some simple functions that can be achieved using FPGA. Meanwhile, ASIC adds some complex functions. SoC typically includes CPU, peripheral buses, and some functional IPs. ASIC often refers to specific functional modules, while SoC contains ASIC.