Long-reach SerDes physical layer specification advancing ADAS, ADS, IVI and other automotive applications

Quick Facts

Key Highlights
  • Targeted for advanced driver assistance systems (ADAS), autonomous driving systems (ADS), in-vehicle infotainment (IVI) and other surround-sensor applications
  • Simplifies integration of lidar, radar and cameras for limited and full vehicle autonomy
  • Improves connectivity for high-resolution safety and infotainment displays
  • Supports functional safety and security
  • Also well-suited for Internet of Things (IoT), industrial and other applications
Fundamental Features
  • Asymmetric data link layer with point-to-point or daisy-chain topology
  • Up to 15-meter reach
  • 5 downlink speed gears (2, 4, 8, 12 and 16 Gbps) with roadmap to 48 Gbps and beyond
  • 2 uplink speed gears (100 and 200 Mbps)
  • Dual-downlink configuration using two data lanes offers a maximum downlink data rate of 32 Gbps
  • Ultra-low packet error rate (PER) of 10-19 for unprecedented reliability over vehicle lifetime
  • High-speed data, control data and optional power share the same physical wiring
  • Reduces complexity, cost, wiring and weight
  • With protocol adaptation layers (PALs), provides support for CSI-2, DSI-2, and VESA’s DP and eDP protocols, without a separate software stack. PALs for I2C, GPIO, Ethernet, SPI* and I3C* command and control channels are also supported (* in development)
  • Ultra-high immunity to automotive EMC effects by virtue of a unique PHY-layer retransmission system
Use Cases

ADAS

ADS

Human machine interfaces (HMI)

In-vehicle infotainment (IVI)

Industries

Icon of an AutomobileIcon of a cloud with the letters IoT inside.

Overview

MIPI A-PHY® is a long-reach serializer-deserializer (SerDes) physical layer interface for automotive applications, including ADAS, ADS and other surround-sensor applications, including cameras and in-vehicle infotainment (IVI) displays.

The specification provides an asymmetric data link in a point-to-point or daisy-chain topology, with high-speed unidirectional data, embedded bidirectional control data and optional power delivery, all over a single cable. This reduces wiring, cost and weight, and allows designers to optimize systems for the performance, cost and complexity required by their use cases, providing scalability and flexibility to meet a broad range of speed and design needs. For integration with existing network backbones, A-PHY complements Ethernet, CAN, FlexRay and other interfaces.

MASS Framework

MIPI A-PHY serves as the foundation of an end-to-end connectivity framework, MIPI Automotive SerDes Solutions (MASS), designed to simplify the integration of cameras, sensors and displays, while also incorporating functional safety and security. Higher-layer MIPI protocols, such as Camera Serial Interface (MIPI CSI-2®) and Display Serial Interface (MIPI DSI-2℠), are already used to connect sensors and displays to domain ECUs and other onboard computers in many vehicles. They currently are transported over MIPI C-PHY℠ or D-PHY℠ shorter-reach physical layers and use "bridge" solutions to connect to proprietary long-reach PHYs. With the use of adaptation layers, these higher-layer protocols will run natively over A-PHY, eliminating the need for these proprietary bridges.

A-PHY v1.1

MIPI A-PHY v1.1, adopted in 2021, introduces several enhancements and is fully backward compatible with v1.0, allowing devices using both releases to coexist on the same network.

A-PHY v1.1 doubles the total downlink data rate supported by A-PHY from 16 to 32 Gbps by adding support for Star Quad (STQ) shielded dual differential pair cables that provide dual differential pairs of conductors within a single shielded jacket. This enables two A-PHY ports over a single cable, saving cost, weight and complexity compared with using two separate coaxial or shielded twisted pair cables.

A-PHY v1.1 also adds optional PAM4 encoding for downlink gears G1 and G2, with data rates of 2 Gbps and 4 Gbps, respectively. PAM4 encoding features lower modulation bandwidth for sub-1 GHz operation, allowing manufacturers to more easily migrate to A-PHY while using either legacy cables on current platforms or lower-cost cables on new platforms.

In v1.1, the maximum uplink data rate is also doubled to 200 Mbps, providing more bandwidth for command and control of automotive peripherals.      

It is anticipated that the first vehicles using A-PHY components will be in production in 2024.

In addition to automotive uses, the specification will be well-suited for applications such as IoT and industrial.

MIPI A-PHY was developed by the MIPI A-PHY Working Group and is available to MIPI Alliance members. A-PHY v1.0 was also adopted as an IEEE standard in June 2021 and is available as IEEE 2977-2021. A-PHY v1.1 will also be submitted for adoption as an IEEE standard. 

For information about becoming a member, see Join MIPI.