Key technologies and international trends in EDA field of digital IC design: a patent analysis

. Currently, Electronics Design Automation (EDA) software tools are highly monopolized internationally. In China, EDA suffers from the pain of "stuck neck". This paper will find out the key technologies in the EDA field through 3D sand table clustering algorithm, and analyze a series of patent data of monopoly three companies (Synopsys, Cadence, Mentor Graphic), in order to help local EDA enterprises perceive the technology status and development trend of the international EDA field.


Introduction
The Integrated Circuit (IC) industry and software industry are the key development areas of the "Made in China 2025" power strategy and the national innovation-driven development strategy [1] .EDA as a software industry in the IC field, the importance is selfevident.
However, there is still a long way to go before the industry chain of chip manufacturing can truly achieve autonomy and control. The biggest difficulty in the field of chip manufacturing in China is the weakness in the manufacturing of lithography machine and the r&d and design of EDA software, which has been deeply stuck in the neck. EDA technology runs through the industrial software system of the entire integrated circuit industry chain. It is the most upstream and basic position of the industry chain, and plays an important strategic support role in design, manufacturing, packaging, testing, application and other links [2] .
At present, the EDA field of IC industry is in a highly monopolised state in the world, especially foreign enterprises Synopsys, Cadence Design Systems, Siemens EDA (Mentor Graphics) occupy nearly 80% of the market, referred to as the "three giants" in the industry. The three giants to a large extent control the EDA ecosystem, has formed a chip design chain upstream and downstream dependence [3] . In the Chinese market, more than 95% of EDA software sales are held by the three giants. In other words, the analysis of the technology status of the big three can help us perceive the technology status of the entire EDA field. The overview of the three companies is shown in Table 1, and the international market share of the three companies is shown in Figure 1.
Therefore, through the patent map analysis of EDA's monopoly giants can help us understand the international market status quo and technology development trend, help local enterprises improve innovation competitiveness, strive to break import dependence as soon as possible.

Data instruction
The research data from incoPat global patent database.The retrieval mode takes EDA and its subsidiaries as the applicant and transferee, retriin multiple languages, retains the invention patent, filtering the utility model patent and design patent, and the application number is not merged. Retrieved time was held on 2020.12.20.And to perform the selective download of the patent writing entries.

3D sand table clustering
The 3D patent sand table is an advanced tool for patent strategy analysis [].The threedimensional topographic map is used to vividly show the competition situation of technology. Wave peaks represent technology-dense areas and wave valleys represent technology blank points. Different colors are used to mark different patent applicants to clearly demonstrate the competition. Each dot represents a patent, and the closer the dot indicates a higher correlation of the technique. Compared with other theme clustering (LDA, etc.), the clustering algorithm of 3D sand table combines the characteristics of the patent itself, and is more professional and accurate for the clustering of technical keywords. The intelligence analysis tool of incopat patent database was applied to visualized the results in Figure 2.Synopsys in blue, Cadence in yellow, and Mentor in red. Line segment length corresponds to quantity proportion, the categories set to 6 and the labels set to 3. As the picture, the patents of EDA three giant enterprises are mainly clustered into five key technical themes: Verification, Simulation, Timing analysis, Layout wiring, and Synthesis.

Overall trend
Patent disclosure lag a certain. Generally invention patent is disclosed 3-18 months after the application.Thus this paper only analyzes the patent application trends. As shown in Figure  3., patent application-disclosure trends of the three giants from 2001-2020. In 2017-2020, The number of patents applied has dropped significantly, High-level monopoly period in the EDA field, Technology development is saturated, It reflects that the overall situation in the EDA field of the international integrated circuit industry is not optimistic.

2 Technical composition analysis
The classification of the technical composition analysis is based on the IPC classification number.According to the more detailed characteristics of the EDA field knowledge system, select the most detailed 'group' category, and the parameter is set to 20, before five as an example. Table 2. is available. It can be concluded that the vast majority of the patents of the three giants belong to the G06F17/50 (CAD) classification, with a total of 6,364 patents, accounting for the highest proportion of 61.91%.

3 Key technology distribution
The statistics according to the five technical themes of "verification", "simulation", "layout wiring", "timing analysis" and "synthesis", concluded the number and distribution of the EDA three giants' patents in various key technology fields. As shown in Table 3. Table 3. Distribution of key technical topics of EDA three giants. Synopsys  269  245  539  48  28  Cadence  291  243  496  49  15  Mentor  171  160  272  31  18  total  731  648  1307  128  61 From the perspective of enterprises, the distribution probability of EDA patents of the three giants on various topics is almost the same. The research results are the most among the five key technologies. Most of the researches of the three giants focus on the three technical topics of 'Verification', 'Simulation' and 'Layout wiring', and there are not many research and development on 'Timing analysis' and 'Synthesis', which intuitively reflects the EDA leading companies in various The degree of development, focus, and areas of expertise on technical topics are not very different.

Verification Simulation Layout wiring Timing analysis Synthesis
From the perspective of technical topics, it can be seen that the number of researches on 'Layout wiring' is far ahead, and the development of EDA technology in this part has been very mature in the world; secondly, there are two technical themes of 'Verification' and 'Simulation' , the number of patents is only about half of 'Layout wiring', these two technologies are very difficult parts in EDA, it can be seen that there is still a certain research and development space; while the three giants have not done much research on 'Timing analysis' and 'Synthesis' two, indicating that there may be more gaps in the technical research and development of these two parts, existing a lot of room for innovation and development.

Technology life cycle
The analysis time span is from 2000 to 2020, results are shown in Figure 4.From the vertical axis, it can be seen that EDA technology was in the development period from 2000

Summary
It can be seen from the above analysis that although EDA technology is monopolized by the Three Giants in the world, the overall development trend is not optimistic, and it is in an obvious bottleneck period. The research and development of key technologies is not comprehensive.There is still a lot of room for expansion in most technologies. Therefore, under the positive policy environment that our country strongly supports the development of the integrated circuit and software industry, it is hoped that local EDA companies can seize the opportunity, strive to break through the "stuck neck" difficulty, take the best of them, and strive to be upstream.