A must-read for chip people | What is chip IP?

"IC, IP, IQ card, tell me the password!" is a classic line from Fan Wei in the movie "A World Without Thieves". In reality, there are no IQ cards, only IC cards and IP cards. IC card refers to integrated circuit card, also called chip card, such as bank card, telecommunication card, transportation card and social security card are all implemented with chip card. IP card is a network phone card that uses TCP/IP protocol. IP card has been eliminated and no longer used. However, TCP/IP protocol has been used as the underlying technology of Internet communication, so words such as IP and IP address can still be heard frequently. This is the first IP, which is a technical term in the Internet field, specifically referring to IP protocol or IP address.

Figure 1. A scene from a robbery on a train in the movie A World Without Thieves

The second type of IP is a legal term, which is the English abbreviation of Intellectual Property. In modern society, many countries attach great importance to the protection of intellectual property rights. The chip industry is a highly intellectual and capital-intensive industry, so the protection of intellectual property rights in this industry is even more important. The intellectual property rights in the chip industry can be called Silicon Intellectual Property, or SIP for short. The protection forms of SIP mainly include patent protection and IC layout protection.

This article will introduce the third type of IP, which is both a technical term and a thing, a commodity. It embodies the wisdom of chip designers, has the attributes of commodities and intellectual property rights, and can be promoted, sold, and applied. Therefore, the chip industry has technological and commercial activities such as IP development, IP trading, and IP reuse, and some companies are also called IP manufacturers and IP providers.

IP in the chip industry is also generally referred to as IP core. IP core refers to the mature design of a circuit module with independent functions in a chip. The circuit module design can be applied to other chip design projects that contain the circuit module, thereby reducing the design workload, shortening the design cycle, and improving the success rate of chip design. The mature design of the circuit module embodies the wisdom of the designer and reflects the designer's intellectual property rights. Therefore, the chip industry uses IP core (Intellectual Property Core) to represent the mature design of this circuit module. IP core can also be understood as an intermediate component of chip design.

Generally speaking, a complex chip is composed of a circuit part designed by the chip designer and multiple purchased IP cores. As shown in Figure 2, to design a chip with such a structure, the design company can purchase all the IP cores in the chip (modules of different colors), design only the creative and independently designed part of the chip (indicated in green), and connect the parts together.

Figure 2. The self-designed part and multiple IP cores are integrated together to form a complex chip design.

The chip design process in Figure 2 is just like the system circuit board development process in Figure 3. It is a process of using existing and mature IP cores (or chips) for layout, placement and signal connection. This process can be called reuse of IP cores (or chips) . The difference is that in addition to chips and connecting wires on the system circuit board, system developers rarely develop their own chips. In the chip design process, in addition to using purchased IP cores on the chip, generally speaking, chip designers also need to design part of their own circuits and complete the signal connections between the parts. Finally, the functions and performance of the entire chip must be repeatedly checked and verified before manufacturing.

Figure 3. Building a complex chip from an IP core is similar to building a complete system circuit board from the chip.

If the above introduction seems too professional, we can use a jigsaw puzzle to illustrate chip design. The chip shown in Figure 2 can be abstractly understood as a jigsaw puzzle shown in Figure 4. The purchased IP cores with different functions in the chip are represented by blocks of different colors, and the self-designed circuit parts are represented by green blocks. The design process of a complex chip is like piecing together this picture. The same thing is that the existing blocks (IP cores) are used to piece together a beautiful picture (complex chip). The difference is that the jigsaw puzzle only considers the shape of the blocks, while the chip design needs to consider many parameters and indicators of the IP core, and the various IP cores and self-designed parts must be correctly connected to ensure the correct function and performance of the entire chip.

Figure 4. IP cores make it easier to design complex chips. IP reuse is like a "puzzle"

The IP core is adopted by other chip design companies, which is called IP reuse in the industry. The design of relatively independent circuit function modules is specifically designed for the purpose of promoting them to other chip design companies for reuse. This kind of design work is called IP development. Companies specializing in IP development are called IP manufacturers or IP providers. IP manufacturers selling IP to chip design companies is an IP transaction.

The origin of IP can be traced back to the early chip design process. The integration scale of early chips was limited, the design complexity was not high, and all the circuits on the chip were completed independently by the chip designer. Chip companies with low design level and limited capabilities can only design small and simple chips. Only chip companies with high design level and strong capabilities can design large-scale and complex chips. During this period, regardless of the size of the chip, the chip was designed by the chip company itself from "head" to "foot". Early high-end chips were basically controlled by a few large international chip companies.

As the modern information society places higher demands on chips, the size of chips has increased exponentially, and the complexity has increased dramatically. It has become almost impossible for small and medium-sized chip companies to independently complete the design of a complex chip. In particular, in the late 1980s, the foundry business model emerged in the chip industry, and a large number of small and medium-sized microchip design companies (Fabless) came into being. During this period, the chip design industry urgently needed to solve the problem that small chip companies could not design large chips.

There are many inspiring ideas to solve this problem. For example: building blocks and jigsaw puzzles; designing large machines from standard parts; designing large software by calling software subroutines (or middleware); building large electronic systems with chips, etc. The ideas are to reuse pre-designed mature components to build more complex systems, eliminating the need to consider the internal problems of the components and simplifying the complex; reuse components to reduce repetitive work and save time; reuse components to increase the success rate of building the entire complex system.

The IP core development and IP reuse in the chip design industry are inspired by these ideas. The IP core is similar to the above-mentioned components. The IP core is a pre-designed circuit module design with independent functions. With the IP core component, large and complex chip design becomes easier, with a shorter cycle and easier to succeed.

IP plays four main roles. First, it simplifies chip design, shortens the chip design cycle, and improves the success rate of complex chip design. Second, IP development and IP reuse technology make it possible for small companies to design large chips. Third, it enables system manufacturers to design their own chips, improve their independent innovation capabilities and the independent intellectual property rights content of the whole system. Fourth, it enables the chip design industry to break away from the traditional IDM model and become an independent industry in the industrial chain, which promotes the rapid development of the chip design industry.

At present, although many small and medium-sized microchip design companies have limited design capabilities and levels, they will outsource many IP cores to complete their chip design projects in order to seize the market and shorten the chip design cycle. The number of IP developers and IP providers in the industry continues to increase, and they are becoming more and more professional. IP cores of various functions and types continue to emerge. IP trading activities are becoming more and more common, and the transaction amounts are also increasing.

IP cores are classified into three levels: behavior level, structure level and physical level , corresponding to three types of IP cores: soft cores (Soft IP Core) designed by hardware description language, firm cores (Firm IP Core) with completed structural description, and hard cores (Hard IP Core) based on physical description and process verified.

1. IP soft core : It is a circuit module with independent functions designed in hardware description language (HDL). From the perspective of chip design, it has only undergone RTL-level design optimization and functional verification, and is usually submitted to users in the form of HDL text. Therefore, it does not contain any physical implementation information, and therefore, IP soft core has nothing to do with manufacturing process.

After purchasing the IP soft core, users can synthesize the correct gate circuit level design netlist and carry out subsequent structural design, which has great flexibility. With the help of EDA synthesis tools, users can easily integrate with other IP soft cores and self-designed circuit parts, and design chips with different performances according to various semiconductor processes.

2. IP solid core : Its design level is between IP soft core and IP hard core. In addition to completing all the designs of IP soft core, it also completes the design links such as gate-level circuit synthesis and timing simulation. Generally, it is provided to users in the form of gate-level circuit netlist.

3. IP hard core : It provides the circuit module at the mask level in the final stage of circuit design. It is provided to users in the form of a final layout and routing netlist. IP hard core has both predictable results and can optimize power consumption and size for specific processes or specific IP providers.

Therefore, the three types of IP cores are the products of circuit functional module design at different design stages, as shown in Figure 5.

Figure 5. Different types of IP cores can be obtained at different stages of circuit functional module design.

After careful evaluation and selection, the user purchases the IP core from the IP vendor and then begins to design his own chip. As mentioned earlier, a complex chip is generally composed of a purchased IP core and a circuit part designed by the user. The chip design process includes three stages: behavioral level, structural level, and physical level. The work at the behavioral and structural level design stages is generally called front-end design, and the work at the physical level design stage is generally called back-end design. The schematic diagram of Figure 6 shows that different types of IP cores are added to the entire chip design at different design stages.

Figure 6. Three types of IP cores are incorporated into the design at different stages of chip design to form an integrated whole

The three types of IP cores have their own advantages and disadvantages, and users will choose according to their actual needs. The following is a brief summary of the advantages and disadvantages of the three types of IP cores.

IP soft core : It is delivered to users in the form of comprehensive source code. Its advantages are that the source code is flexible, can be reconfigured at the functional level, and can flexibly select the target manufacturing process. It has high flexibility and strong portability, allowing users to self-configure. Its disadvantages are that the predictability of circuit function modules is poor, there is a possibility of errors in subsequent designs, and there are certain design risks. In addition, it is difficult to protect the intellectual property rights of IP soft cores.

IP solid core : Its flexibility and success rate are between IP soft core and IP hard core, which is a compromise type. Compared with IP soft core, IP solid core has slightly lower design flexibility, but has greatly improved reliability. At present, IP solid core is one of the mainstream forms of IP core.

IP hard core : Its biggest advantage is to ensure that performance, such as speed and power consumption, reaches the expected effect. However, IP hard core is related to the manufacturing process, and it is difficult to transfer to a new process or integrate into a new structure, and it cannot be reconfigured. The feature that IP hard core cannot be modified makes it difficult to reuse, so it can only be used in certain specific applications and has a narrow scope of use. However, the intellectual property protection of IP hard core is the most convenient.

Examples of IP cores include various types of CPU IP cores from ARM. Many IP suppliers offer a wide variety of DSP IP cores, USB IP cores, PCI-X IP cores, WiFi IP cores, Ethernet IP cores, and embedded memory IP cores.

If classified by major categories, it can be roughly divided into processor and microcontroller IP, memory IP, peripheral and interface IP, analog and mixed circuit IP, communication IP, image and media IP, etc.

Some of the world's largest EDA suppliers are also IP suppliers. For example, Synopsys of the United States can provide thousands of IPs of various types, covering IPs in logic libraries, embedded memories, analog libraries, wired and wireless interfaces, security, embedded processors, and subsystems.

As can be seen from Figures 4 and 5, the IP core development process is similar to the chip design process. Both require keeping up with the development trend of chip technology, constantly accumulating chip design technology, and understanding the pace of chip manufacturing process development. The difference is that the business model of chip design companies is to design complete chips and bring them to market to achieve chip sales profits. IP developers do not design complete chips. They only design certain functional modules of the chip, and pursue the optimization of the design of these functional modules (IP cores), and achieve the adaptability and convenience of IP cores in multiple reuse occasions. IP developers seek to enable these IPs to be purchased and adopted by many chip design companies, and achieve IP sales profits.

However, IP development has high technical difficulty and requirements, and it is not something that any chip design company can do as it pleases. This is mainly reflected in the requirements for the completeness of IP. As a component of chip design, IP core can be compared with the component (middleware) of software design. Small flaws can be hidden in software components, and the integrated system software can be continuously improved through patch upgrades when it is put into practical application. But the IP core must be very perfect and cannot have any flaws. Because any small flaw in the IP core may affect the success or failure of the entire complex chip design, and affect the input-output of the entire chip research and development that costs millions or even hundreds of millions of yuan. Therefore, the price of complex IP cores is extremely expensive, ranging from hundreds of thousands to millions of yuan.

In order to facilitate promotion, IP manufacturers generally adopt a business model of charging an initial IP license fee (IP License) + a later royalty fee (Royalty) calculated based on chip shipments to reduce users' R&D investment. Second, IP has multiple parameter requirements, including process nodes, power supply, power consumption, performance, etc. These require IP developers to be very familiar with chip design, manufacturing processes, and industry applications. Third, users have credibility requirements for IP providers, including the company's technical strength, influence, and stability. It is difficult for users to accept IPs provided by a small, unstable IP manufacturer, even if these IPs are cheap or even free. Users would rather buy more expensive IPs from famous, large IP manufacturers, because such IPs have quality assurance and follow-up service guarantees.

Since 2000, with the promotion of Document No. 18 of the State Council and eight national IC design industrialization bases, domestic IC design companies have sprung up and developed rapidly. Most of these companies are small and medium-sized IC design companies. Thanks to IP development and IP reuse technology, these small and medium-sized IC design companies can develop various functional system-on-chips (SOC), artificial intelligence (AI) chips, Internet of Things (IoT) chips, etc. in a timely manner according to market needs. These have promoted the rapid development of the domestic IC design industry and driven the development of my country's new generation of information technology industry. It can be said that wafer foundry technology, IP development and IP reuse technology have laid the foundation for the rapid development of my country's current chip industry.

References:

1. Electronics Encyclopedia Dictionary: IP Core, Cogobuy:

https://www.cogobuy.com/wiki-3064.shtml

2.oLinXi1234567 What is an IP core? , CSDN blog:

https://blog.csdn.net/oLinXi1234567/article/details/40682869 2014.11.1

3. Longbow's persistence, FPGA IP soft core, hard core and solid core, CSDN blog:

https://blog.csdn.net/wordwarwordwar/article/details/53415523, 2016.11.30

4.liwliwliw, Integrated Circuit and IP Core Technology, CSDN Blog:

https://blog.csdn.net/liwliwliw/article/details/91969797, 2019.6.14

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