Domestic Low-Power MIPI A-PHY Serdes Chip Applications in Automotive Technology

Since its establishment in 2019, Chiptech has focused on the design and application of high-end analog integrated circuits, with products widely used in automotive, industrial, communication, medical, and electronic fields, and has been awarded the title of “National High-tech Enterprise Specialized New Little Giant”.

On November 15, 2024, at the Fourth Automotive Chip Industry Conference, Chiptech CEO Wu Guanglin pointed out that in-vehicle image data transmission is one of the core application scenarios of Serdes technology. By converting parallel data into serial data, efficient and low-cost transmission is achieved. Chiptech’s Serdes products not only support various protocols such as MIPI A-PHY and D-PHY but also have excellent compatibility and reliability, meeting the application requirements for video image transmission under complex conditions.

Wu Guanglin | CEO of Chiptech

The following is a summary of the speech content:

Chiptech was established in August 2019, focusing on high-end analog integrated circuit design applications, with products mainly targeting the automotive, industrial, communication, medical, and electronic fields. It has successively received honors such as National High-tech Enterprise, Shanghai Specialized New Small and Medium-sized Enterprises, and National Specialized New Little Giant Enterprise. Currently, our main products include analog-to-digital converters, digital-to-analog converters, and in-vehicle Serdes products, with over 27 invention patents. Our R&D centers are located in Shanghai and Suzhou.

In-vehicle Serdes technology, or serializer and deserializer, can convert parallel data into serial data for transmission via cables, offering advantages such as reduced costs, improved real-time performance, and high-speed capabilities, along with excellent electromagnetic interference immunity.

The camera module outputs standard data via the image sensor, which is packaged and converted to A-PHY protocol through the serializer, and then restored to C-PHY or D-PHY protocol through the deserializer for processing at the SOC interface. After processing, the data is serialized again and sent to the display end after deserialization. Serdes technology is widely used in in-vehicle video transmission at both the camera and display ends.

In terms of application scenarios, Serdes is mainly used in 360-degree surround view, autonomous driving, in-vehicle assistance, and driver monitoring. With the increase in the number of vehicle cameras, the demand for display-end Serdes has also grown significantly. Multiple screens in the vehicle, such as central control screens, rearview screens, and entertainment screens, all require support from Serdes technology.

Camera pixel resolution has increased from early 1-2 megapixels to the current 8 megapixels, and display resolution has evolved from 1080p to 4k, placing higher demands on data transmission rates and reliability. Additionally, differences in cable lengths and materials across different vehicle models pose compatibility and reliability challenges for the Serdes protocol.

Image source: Speaker’s material

The Serdes market is vast, with the global market exceeding 10 billion RMB last year and growing rapidly. It is expected that by 2025, China’s automotive sales will reach 30 million units, with the number of Serdes chips per vehicle expected to reach 14.

In terms of Serdes protocols, early new energy vehicles mainly adopted the GSML proprietary protocol, while public protocols such as MIPI are gradually becoming more popular. As a member of the MIPI Alliance, Chiptech actively promotes the localization of the MIPI A-PHY protocol and the construction of a public protocol ecosystem, participating in the discussion of standard formulation. Compared to proprietary protocols, public protocols have advantages such as strong innovation and iteration capabilities, high product transparency, clear testing standards, and unified application standards, attracting many manufacturers to invest in research and development, and are expected to break the technical incompatibility and market monopoly issues of proprietary protocols, ensuring supply chain safety for OEMs and Tier 1 manufacturers, and further reducing BOM costs.

The A-PHY standard began to be formulated in 2015 and officially released version 1.0 in 2020. This is the world’s first long-distance serializer/deserializer (Serdes) physical layer interface specification for automotive applications. Since 2021, we have chosen to develop this public protocol.

One significant advantage of the A-PHY protocol is that it allows SOCs to use this standard, enabling future integration. However, since SOCs cannot integrate all functions, especially data transmission interfaces, bridging and transitioning technologies are also essential in the face of the growing number of interfaces. The A-PHY protocol enables data communication control and power transmission through a single wire, greatly simplifying system costs. It supports bidirectional, frequency division transmission, with different upstream and downstream transmission rates; the latest standard can achieve a forward rate of up to 32G, significantly enhancing data throughput, and supports various interfaces. The reverse transmission rate is also continuously improving, currently reaching a maximum of 1.6Gbps. The A-PHY protocol supports various cabling materials, including coaxial and twisted pair cables, with transmission distances of up to 20-40 meters, depending on cable quality. Additionally, the A-PHY standard has clear specifications for electromagnetic interference, large current injection, and narrowband interference, fully ensuring anti-interference capabilities.

Image source: Speaker’s material

Numerous standard manufacturers and testing organizations support the A-PHY protocol, allowing it to be widely used in autonomous driving, intelligent cockpits, and in-vehicle entertainment. Its advantages include strong anti-interference capabilities, global automotive design standards, and transmission rates of up to 32G, attracting numerous manufacturers to support it and significantly reducing costs.

To develop the A-PHY public protocol ecosystem, participation is needed not only from chip R&D manufacturers but also from domestic chip R&D companies, manufacturers, host manufacturers, research institutions, SOC manufacturers, Serdes image module ends, as well as universities and research institutes, to jointly promote the development of the ecosystem.

SCS5501 is a serializer chip that can convert D-PHY interface data from the camera end into A-PHY protocol data. This chip supports transmission rates from 2G to 4G, enabling single-wire transmission via A-PHY, supporting POA (power over A-PHY), and simultaneously providing clock to the camera. The SOC can control Serdes via GPIO and I2C, achieving image transmission and power supply through a single wire.

In terms of the deserializer, SCS5502 supports four-channel A-PHY input, enabling surround view functionality. After four-channel data input, it is converted into D-PHY data for SOC use. The SOC can remotely control Serdes via GPIO and I2C. D-PHY configuration is flexible, supporting one, two, or four-channel configurations, with a rate of 2.5Gbps per channel, totaling 10Gbps for four channels, and up to 20Gbps for two ports, supporting 8-megapixel data transmission to meet mainstream camera requirements.

Our products have significant advantages in terms of power consumption, and low power consumption means lower heat generation, which is a huge advantage for the module end. The products also demonstrate excellent multi-platform compatibility.

In terms of product reliability certification, we have obtained ASIL-B certification and automotive-grade AEC-Q100 certification, with complete certification reports from a third-party authoritative laboratory with CNAS qualification.

Image source: Speaker’s material

In September 2024, Chiptech successfully achieved physical layer interoperability with Israel’s Valens company in Beijing, with the participation and witnessing of DeTech company. In November 2024, Chiptech conducted image transmission tests from Sensor to ECU with Israel’s Valens company, successfully achieving application layer remote control and image transmission.

The main advantages of Chiptech SCS5501/2 include: fully domestic production, independently developed IP with proprietary intellectual property rights; excellent multi-platform compatibility; core technology solving signal adaptive problems, capable of matching more cables and connectors; P2P compatibility with competing models without the need to modify hardware design; achieving interoperability of A-PHY protocol chips, truly realizing a public protocol; ultra-low power consumption, significantly reducing heat generation.

The standard D-PHY platform outputted by our deserializer supports mainstream SOC platforms, such as TI TDA4, Qualcomm, MTK, etc., making it a rapid mass production platform. We have verified these performance metrics in practical applications, for example, using Sony cameras on the TDA4 surround view platform.

Chiptech will continue to work with industry partners to promote the implementation of the Chinese A-PHY public protocol!

(The above content is derived from the keynote speech “Chiptech Domestic Low-Power MIPI A-PHY Serdes Chip Applications in Automotive Technology” delivered by Chiptech CEO Wu Guanglin at the Fourth Automotive Chip Industry Conference on November 15, 2024.)