SoC

System on chip

System on Chip, or SoC for short, is also a system on chip. From a narrow perspective, it is the chip integration of the core of the information system, which is to integrate the key components of the system on a chip; from a broad perspective, SoC is a miniature system. If the central processing unit (CPU) is the brain, then the SoC It is the system that includes the brain, heart, eyes, and hands. Academia at home and abroad generally tends to define SoC as integrating a microprocessor, analog IP core, digital IP core and memory (or off-chip memory control interface) on a single chip, which is usually customized by the customer or for specific purposes Standard product.

The basic content of SoC definition is mainly in two aspects: one is its composition, and the other is its formation process. The system-level chip can be composed of a system-level chip control logic module, a microprocessor/microcontroller CPU core module, a digital signal processor DSP module, an embedded memory module, an interface module that communicates with the outside, and an ADC/DAC-containing Analog front-end module, power supply and power management module. For a wireless SoC, there is also a radio-frequency front-end module, user-defined logic (which can be implemented by FPGA or ASIC), and a microelectronic mechanical module. More importantly, a SoC chip is embedded with Basic software (RDOS or COS and other application software) modules or loadable user software, etc. The system-level chip formation or production process includes the following three aspects:

1) Co-design and verification of software and hardware based on monolithic integrated system;

2) Reuse the use of logical area technology and the proportion of production capacity to effectively improve the development and research of IP core generation and multiplexing technology, especially the repeated applications embedded in large-capacity storage modules;

3) Design theory and technology of ultra-deep submicron (VDSM) and nano-integrated circuits.

The key technology of SoC design

SoC key technologies mainly include bus architecture technology, IP core reusable technology, software and hardware co-design technology, SoC verification technology, testability design technology, low power design technology, ultra deep sub-micron circuit implementation technology,

And including doing embedded software transplantation, development research, is a new interdisciplinary research field.

Summary

SoC is an abbreviation of System on Chip, which literally means "chip-level system", usually abbreviated as "system on chip". Because it involves "Chip", the SoC will also reflect the connection and difference between "Integrated Circuit" and "Chip", and its related content includes integrated circuit design, 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 chip, which contains complete Hardware system and embedded software that it carries.

This means that a single chip can complete the function of an electronic system, and this system used to require one or more circuit boards, as well as various electronic devices, chips and interconnections on the board to cooperate to achieve . Earlier, when we talked about integrated circuits, we mentioned the integration of buildings and bungalows, and SoC can be seen as the integration of buildings in cities and towns; hotels, restaurants, shopping malls, supermarkets, hospitals, schools, bus stations, and a large number of residences, gathered together , Constitutes the function of a small town, to meet the basic needs of people to eat, live, and travel. SoC is more about the integration of the processor (including CPU, DSP), memory, various interface control modules, and various interconnection buses. Its typical representative is the mobile phone chip (see the introduction of the term "terminal chip"). SoC has not yet reached the level of a single chip to realize a traditional electronic product. It can be said that SoC only realizes the function of a small town, but cannot realize the function of a city.

SoC has two notable features: one is the large scale of hardware, usually based on the IP design model; the second is that the proportion of software is large, which requires software and hardware co-design. It can be analogized that the advantages of cities over rural areas are obvious: complete facilities, convenient transportation and high efficiency. SoC also has similar characteristics: more supporting circuits are integrated on a single chip, saving the area of the integrated circuit, which also saves costs, which is equivalent to the improvement of the city's energy utilization rate; on-chip interconnection is equivalent to the urban fast road, high speed , Low consumption, the information transmission between the devices originally distributed on the circuit board is concentrated in the same chip, which is equivalent to the place that can be reached by long-distance bus. It has moved to the city and took a subway. Or BRT is here, which is obviously much faster; the city’s tertiary industry is developed and more competitive, and the software on the SoC is equivalent to the city’s service business, not only hardware, but also software; the same set of hardware, Today it can be used to do something, and tomorrow it can be used to do another thing, similar to the improvement of resource allocation and scheduling and utilization of the entire society in the city. It can be seen that SoC has obvious advantages in performance, cost, power consumption, reliability, and life cycle and scope of application, so it is an inevitable trend in the development of integrated circuit design. In the field of terminal chips sensitive to performance and power consumption, SoC has occupied a dominant position; and its application is expanding to a wider field. The realization of a complete electronic system with a single chip is the future development direction of the IC industry.

Technological development

The development of integrated circuits has a history of 40 years. It has been advancing in accordance with the laws indicated by Moore and has now entered a deep sub-micron stage. Due to the needs of the information market and the development of microelectronics itself, it has triggered the development of a variety of process integration technologies and application-oriented system-level chips that are characterized by microfabrication (the feature size of integrated circuits is continuously shrinking). As the semiconductor industry enters the era of ultra-deep submicron and even nano-processing, a complex electronic system, such as mobile phone chips, digital TV chips, DVD chips, etc., can be implemented on a single integrated circuit chip. In the next few years, hundreds of millions of transistors and tens of millions of logic gates are expected to be implemented on a single chip. SoC (System-on-Chip) design technology began in the mid-1990s. With the development of semiconductor process technology, IC designers can integrate increasingly complex functions on a single silicon chip. SoC is in integrated circuits (IC) to the integrated system (IS) transition under the general direction. The FlexCore system released by Motorola in 1994 (used to make custom microprocessors based on 68000 and PowerPC) and the SoC designed for Sony by LSILogic in 1995 may be the earliest report to complete the SoC design based on IP (IntellectualProperty) core. Because SoC can make full use of the existing design accumulation and significantly improve the design capabilities of ASIC, the development is very rapid, which has attracted the attention of industry and academia. [2] 

SOC is the inevitable trend of integrated circuit development, the inevitable development of technology, and the future development of IC industry.

Other

Technical characteristics

System integration of semiconductor process technology

Integration of software system and hardware system

Advantage

Reduce power consumption

Reduce volume

Increase system functions

accelerate

cut costs

There is a problem

The current chip design industry is facing a series of challenges. System-on-chip SoC has become the focus of the IC design industry. SoC performance is getting stronger and stronger, and the scale is getting bigger and bigger. The scale of SoC chips is generally much larger than that of ordinary ASICs. At the same time, due to the design difficulties brought by deep sub-micron technology, the complexity of SoC design is greatly increased. In SoC design, simulation and verification is the most complex and time-consuming part of the SoC design process, accounting for about 50% to 80% of the entire chip development cycle. The use of advanced design and simulation verification methods has become the key to the success of SoC design. The development trend of SoC technology is based on the SoC development platform. The platform-based design is an integration-oriented design method that can achieve maximum system reuse, share the results of IP core development and system integration, and continuously restructure the value chain. On the basis of delay and power consumption, it shifts to yield, reliability, electromagnetic interference (EMI) noise, cost, ease of use, etc., enabling rapid development of system-level integration capabilities. The so-called SoC technology is a highly integrated and firmware-based system integration technology. The core idea of designing a system using SoC technology is to integrate the entire application electronics system into a single chip. When using SoC technology to design an application system, all the other system circuits are integrated together, except those external circuits or mechanical parts that cannot be integrated.

Core technologies

System function integration is the core technology of SoC

In the design of traditional applied electronic systems, it is necessary to integrate the entire system according to the functional modules required by the design, that is, to find the corresponding integrated circuits according to the functions required by the design, and then to design the connection form of the selected circuit according to the technical specifications of the design requirements and parameter. The result of this design is a distributed application electronic system structure based on functional integrated circuits. Whether the design results can meet the design requirements depends not only on the technical parameters of the circuit chip, but also on the electromagnetic compatibility characteristics of the PCB layout of the entire system. At the same time, for systems that need to be digitized, there is often a need for microcontrollers to participate, so you must also consider the impact of distributed systems on the characteristics of circuit firmware. Obviously, the implementation of traditional application electronic systems uses distributed function synthesis technology.

For SoCs, the design of applied electronic systems is also based on functional and parameter requirements, but it is essentially different from traditional methods. SoC is not a distributed system synthesis technology based on functional circuits. It is a system firmware and circuit synthesis technology based on functional IP. First of all, the realization of functions is no longer integrated for functional circuits, but integrated circuits for the overall firmware implementation of the system, that is, the use of IP technology to integrate the entire system. Secondly, the final result of the circuit design is related to the IP function module and the firmware characteristics, but basically has nothing to do with the way of circuit division on the PCB board and the connection technology. Therefore, the electromagnetic compatibility characteristic of the design result is greatly improved. In other words, the designed result is very close to the ideal design goal.

The key technologies of SoC design mainly include bus architecture technology, IP core reusable technology, software and hardware co-design technology, SoC verification technology, testability design technology, low power design technology, ultra-deep sub-micron circuit implementation technology, etc. It is also an emerging interdisciplinary research field to do embedded software transplantation and development research.

Design thinking

Firmware integration is the basic design idea of SoC

In the traditional distributed integrated design technology, the firmware characteristics of the system are often difficult to achieve optimal, because the distributed function integrated technology is used. In general, in order to meet as many application surfaces as possible, functional integrated circuits must consider two design goals: one is to meet the functional control requirements of multiple application areas; the other is to consider satisfying a wide range of application functions and technologies index. Therefore, functional integrated circuits (that is, custom-made integrated circuits) must add several circuits in the I/O and control aspects, so that the general user can get as much development performance as possible. However, it is not easy to achieve the best application electronic system for customized circuit design, especially the firmware characteristics are quite decentralized.

For SoC, it can be seen from the core technology of SoC that the basic design idea of using SoC technology to design and apply electronic systems is to implement firmware integration of the entire system. Users only need to select and improve each part of the module and embedded structure according to their needs, and they can achieve fully optimized firmware features without having to spend time familiarizing themselves with custom circuit development techniques. The sudden advantage of the firmware foundation is that the system can be closer to the ideal system, and it is easier to achieve the design requirements.

basic structure

Embedded system is the basic structure of SoC

In the application electronic system designed with SoC technology, the embedded structure can be realized very conveniently. The implementation of various embedded structures is very simple, as long as the corresponding core is selected according to the system needs, and then the matching IP module is selected according to the design requirements, the entire system hardware structure can be completed. Especially when the intelligent circuit synthesis technology is adopted, the firmware characteristics of the entire system can be more fully realized, so that the system is closer to the ideal design requirements. It must be pointed out that this embedded structure of SoC can greatly shorten the application system design and development cycle.

basics of design

IP is the basis of SoC design

Traditional application electronic design engineers face various customized integrated circuits, while electronic system design engineers using SoC technology face a huge IP library. All design work is based on IP modules. SoC technology turns applied electronic system design engineers into application-oriented electronic device design engineers. It can be seen that SoC is a design technology based on IP modules, and IP is the foundation of SoC applications.

designing process

Different stages in SoC technology

Several stages of designing application electronic system with SoC technology are shown in Figure 1. In the functional design stage, the designer must fully consider the firmware characteristics of the system and use the firmware characteristics for comprehensive functional design. When the functional design is completed, you can enter the IP synthesis stage. The task of IP synthesis stage uses powerful IP library to realize the function of the system. After the IP combination is over, first perform functional simulation to check whether the design function requirements of the system are realized. After the functional simulation is passed, it is the circuit simulation, the purpose is to check whether the circuit composed of the IP module can realize the design function and reach the corresponding design technical index. The final stage of the design is to test the manufactured SoC products accordingly in order to adjust various technical parameters and determine the application parameters.

Design methodology

1. Design reuse technology

The system-level chip design with millions of gates cannot start from scratch, and the design should be built on a higher level. IP multiplexing technology needs to be used more. Only in this way can the design be completed quickly, to ensure the success of the design, and to obtain a low-cost SoC to meet market demand.

The design reuse is based on the core (CORE), which is to make the core circuits of various super macrocell modules that have been verified to be used for future design and utilization. The core is usually divided into three types, one is called the hard core, which has a physical layout that is connected to a specific process, and has been verified by wafer testing. It can be directly called as a specific function module by the new design. The second type is soft core, which is written in hardware description language or C language and used for functional simulation. The third type is the solid core (firm core), which is developed on the basis of a soft core and is a soft core that can be synthesized with layout planning. The design reuse method relies heavily on the solid core, and the RTL-level description is combined with the specific standard cell library to perform logic synthesis optimization to form a gate-level netlist, and then form the hard core required by the design through the layout and wiring tools. This soft RTL synthesis method provides some design flexibility, can be combined with specific applications, modify the description appropriately, and re-verify to meet specific application requirements. In addition, with the development of process technology, the new library can also be used to re-optimize, place and route, and re-verify to obtain a hard core under new process conditions. Compared with the traditional module design method, the efficiency of design reuse can be improved by 2 to 3 times with this method. Therefore, the design reuse before 0.35um process uses this RTL soft core.

2. Comprehensive method

With the development of process technology, deep submicron (DSM) makes system-level chips larger and more complex. This comprehensive approach will encounter new problems, because as the process progresses to 0.18um or smaller size, it is not the gate delay but the interconnect delay that needs to be accurately handled. Coupled with the hundreds of megahertz clock frequency, the timing relationship between the signals is very strict, so it is difficult to achieve the purpose of design reuse with a soft RTL synthesis method.

The system-level chip design based on the core core shifts the design method from circuit design to system design. The design focus will shift from today's logic synthesis, gate-level layout and wiring, post-simulation to system-level simulation, software and hardware co-simulation, and several The physical design of the combination of the cores. Forcing the design industry to polarize, one is to turn to the system and use IP to design high-performance, high-complexity, dedicated systems. On the other hand, designing the core under DSM into the physical layer design makes the DSM core better and predictable.

3. Low-power design technology

System-level chips will have power consumption of tens of watts or even hundreds of watts due to the integration of more than one million gates and hundreds of megaclocks. The huge power consumption brings problems to the use of packaging and reliability, so the design to reduce power consumption is an inevitable requirement for system-level chip design. The design should start from many aspects to reduce chip power consumption.

Application News

On August 20, 2014, the domestic color TV giant Skyworth held a new product launch conference in Beijing with the theme of "Moment of Witnessing G", and released the world's first GLED TV in high profile. This conference is a heavyweight. Not only did all the senior leaders of Skyworth Group attend, but also invited the director of the Ministry of Industry and Information Technology, and more than 160 domestic mainstream media and industry experts.

At the meeting, the director of the Ministry of Industry and Information Technology delivered a speech, the content of the speech said: Skyworth Group and Huawei Hisilig have formed a close partnership with the project as the link, and successfully developed China’s first independent research and development and mass production of high-end smart TV chips The chip performance is better than similar chips in the market, which is of great significance to changing the situation of lack of cores and screens in China's color TV industry and enhancing the core competitiveness of the electronic information industry!

On August 21, 2014, "Newscast" reported: "The Chinese local company Skyworth and Haisi independently developed a smart TV SOC chip that was successfully developed and achieved mass production for the first time. The system speed and decoding capabilities of the new Skyworth GLED equipped with this chip The core performance of smart TVs is at the leading level in the industry.” At the same time, Skyworth’s “Smart TV SOC chip R&D and industrialization” project has applied for the “Key Electronic Devices, High-end Universal Chips and Basic Software Products” National Science and Technology Major Project "Major Project"), Skyworth will cooperate with HiSilicon in core areas such as chip definition, chip verification, chip R&D and industrialization. The first 4,000 new Skyworth G8200 series products equipped with this chip were launched on August 20, 2014.