Get a comprehensive understanding of mobile SoC chips, interpreting Xiaomi's mysterious ring

The views in this article come from the public account Chuangxin Observation

Out of the blue, Lei Jun suddenly announced that Xiaomi's decade-long secret weapon—the self-developed mobile phone SoC chip "Xuanjie O1" is coming!

Lei Jun posted another update, stating: "Ten years of drinking ice, hard to cool the blood," expressing the hardships of making chips. Xiaomi has been on the chip-making journey for over ten years, and everyone knows that making chips is difficult. So why is it even harder to make mobile phone SoC chips? Let me take you through a detailed interpretation!

01 What is SoC

First, what is SoC? More than 20 years ago, I discussed with colleagues about a new chip technology abroad called SoC, which stands for System on Chip, and how it should be translated. Essentially, when we create an electronic product, different functions require different chips to achieve them. SoC integrates these different functions into one chip, realizing a small system. For example, functions that previously required five or ten chips can now be accomplished with just one chip, which is a boon for chip users. Instead of having to look at the technical documentation for ten chips to see how to design and make the circuit board, now you only need to understand one chip, greatly reducing the workload.

Based on this principle, we later translated SoC as "system on chip," also known as "system-level chip."

02 What functions does SoC have?

Now let's take a look at what functions are integrated into mobile phone SoCs.

Xiaomi's Xuanjie O1 has not yet disclosed specific performance indicators, so let's take last year's flagship mobile phone SoC chip released by Qualcomm as an example to discuss the main functions included in this chip:

First and foremost, the core is definitely the processor family! The CPU acts like the brain for calculations, the GPU specializes in graphics rendering to ensure smooth gaming, and now there are dedicated NPUs for handling AI tasks, such as scene recognition during photography.

Additionally, the storage system is particularly crucial, such as the various levels of cache memory used for temporarily storing data. It works in conjunction with the processor to prevent the phone from lagging.

Moreover, the most important external communication functions are also integrated into the SoC, including the 5G communication, Wi-Fi, Bluetooth, and other functionalities we use.

Power management unit: By dynamically adjusting the chip's supply voltage and frequency, the power management unit can achieve low-power operation, extending the battery life of the phoneOther functional modules: Depending on application requirements, SoC chips may also include other functional modules, such as audio processors, imaging units, security modules, etc.

03 Why must mobile phones use SoC chips?

In fact, the main directions driving the continuous development of mobile phones are just a few: higher performance, lighter and thinner designs, longer standby times, which align well with the characteristics of SoC.

Compared to traditional multi-chip solutions, SoC has significant advantages in performance, power consumption, and cost due to its highly integrated design:

1. Small size, space-saving

Integrating all core modules into a single chip significantly reduces the circuit board area. For example, mobile phones can be made lighter and thinner while freeing up more space for components like batteries and cameras.

2. Low power consumption, improved battery life

After module integration, the data transmission path within the chip is shorter, reducing signal delay and energy loss. For example, Apple's A-series chips significantly reduce AI task power consumption through collaborative computing between the CPU, GPU, and NPU.

3. Stronger performance, efficient collaboration

The integrated design allows various modules to share resources such as memory and buses, optimizing computing power allocation through unified scheduling. For example, Huawei's Kirin chip's NPU collaborates with the ISP to achieve real-time video background blurring.

4. Lower costs, advantages in mass production

For a single chip, packaging and testing costs are much lower than those of multi-chip combinations. This reduces overall hardware costs and lowers development complexity for mobile developers, speeding up the time to market for new phones.

SoC vs Traditional CPU: Essential Differences

04 Problems to Solve in SoC Development

Looking at these functions, one can understand how difficult it is to develop SoC, and many of the challenges cannot be solved solely by technology.

Creating a capable mobile chip is like dancing on the tip of a needle—technically challenging, financially demanding, and time-consuming. Here are a few major issues:First, there is a significant technical difficulty, as it requires fitting various modules such as processors, basebands, and interfaces into a chip the size of a fingernail. Not only must everything "fit," but they also need to work together without conflicts, overheating, and to perform at their best efficiency. It cannot fail midway, making the difficulty evident.

Secondly, to achieve low power consumption, strong performance, and have an advantage over competitors with greater commercial value, the most advanced manufacturing processes must be adopted. According to reports, Apple's M3 series chips for desktop and tablet applications are manufactured using TSMC's latest 3nm process, costing up to $1 billion in design and tape-out. Even more frustrating is that the most advanced production lines are controlled by others. You can't just use them whenever you want.

The patent issues in the mobile chip design field are like an invisible war, directly determining the survival of manufacturers. A real case is the 5G patent battle between Apple and Qualcomm, where Apple ultimately capitulated, paying at least $4.5 billion to Qualcomm and signing a six-year patent licensing agreement. This illustrates the lethal power of patents.

95% of mobile chips globally are based on ARM architecture, requiring hundreds of millions of dollars in patent fees each year.

Huawei has applied for over 200,000 patents, and in the past five years, over 2 billion phones have obtained Huawei's 4G and 5G patent licenses. In 5G patent declarations, Huawei's 5G patents account for 14%, ranking first globally. In 2022, Huawei's global patent licensing fees amounted to $1.2 billion.

05 A Review of Xiaomi's Chip Development Journey

Xiaomi's chip development journey can be divided into two phases. In 2014, Xiaomi established the chip brand "Pinecone" and launched its chip development business. After nearly three years, Xiaomi released the Surge S1 mobile chip in 2017, which was first used in the Xiaomi 5C.

The Surge S1 was positioned as a mid-range mobile chip, manufactured using TSMC's 28nm process. However, at that time, this chip was considered relatively outdated in terms of manufacturing process and had issues such as insufficient baseband capability, high power consumption, and overheating, ultimately being used only in the Xiaomi 5C before fading away. According to rumors, the subsequent Surge S2 chip experienced five failed tape-outs, forcing Xiaomi to suspend its main chip development work.

Xiaomi's chip development then entered the second phase, shifting towards "small chips," successively launching self-developed imaging chips in the Surge C series, charging chips in the Surge P series, and self-developed battery management chips in the Surge G series.

Lei Jun once stated that developing chips is the pinnacle of mobile technology, and Xiaomi must master this core technology to rank among the world's top mobile manufacturers.

According to internal sources, the subsequent development of the Surge S2 chip faced five failed tape-outs, and given the high barriers to 5G baseband development, Xiaomi ultimately suspended its mobile SoC project and shifted to developing peripheral chips such as Bluetooth and RF.

According to public information, Xiaomi successfully tape-out the first domestic 3nm mobile system-level chip as early as 2024. Tape-out, as a key step in chip development, indicates that Xiaomi has completed the entire process from design to sample testing, and the officially announced Xuanjie O1 is likely this chip manufactured using the 3nm processCurrently, Xiaomi has not announced the detailed specifications of the Xuanjie O1, but according to various leaked messages, its CPU may adopt a "1+3+4" octa-core design, with performance comparable to the Snapdragon 8 Gen 1, which is a relatively mature and reliable solution.

People's Daily highly praised the significance of Xiaomi's self-developed chips on the 15th, stating, "In the past year, Xiaomi has continuously brought breakthroughs and innovations in the fields of new energy vehicles and domestic chips. This proves that as long as we are determined and practical, there are no insurmountable mountains; as long as we strive to catch up, there will always be opportunities for latecomers."