2020 BRN Discussion, page-12047

Does anyone know the Xilinx XA7Z010 SoC dual-core ARM Cortex-A9 product?


Is Akida better than Xilinx XA7Z010 SoC dual-core ARM Cortex-A9?

Lidar technology

The key element in the Audi A8 is the lidar. This is the first time when the carmaker used the laser scanner. It is a lidar based on a mechanical system with rotating mirror technology and 905 nm wavelength in edge-emitting technology. The device offers a range of 150 meters with a FOV of 145° horizontal and 3.2° vertical. The motor control unit consists of a stator and rotor with a control driver and MPS40S hall sensor for motion detection. A Hall-effect sensor varies its output voltage in response to a magnetic field. It is a long-lasting solution because there are no mechanical parts to wear down over time. The integrated package reduces the size of the system and the relative complexity of implementation (figures 9, 10, 11).

Lidar systems are based on time of flight (ToF), which measures precise timing events (figure 12). The latest developments have seen several multi-beam lidar systems, which generate an accurate, three-dimensional image of the environment around the vehicle. This information is used to choose the most appropriate driving maneuvers.

Figure 9: Laser scanner (Image: System Plus)Figure 10: the internal part of the laser scanner implemented in Audi A8

Figure 11: Block diagram of the laser scannerFigure 12: Time-of-flight functional diagram (Image: Maxim Integrated)

Edge-emitting lasers are the original and still widely used form of semiconductor lasers. Their resonance length allows achieving high gain. Within the structure, the laser beam is guided in a typically dual hetero-structure waveguide structure. Depending on the physical properties of the waveguide, it is possible to achieve an output with high beam quality but limited output power or high output power but low beam quality (Fig. 13).

Figure 13: Edge emitting Laser diode

The laser used in the lidar solution has a 3-pin TO-type package with a die area of 0.27 mm² as shown in Figure 13. The laser has a power of 75 W and a diameter of 5.6 mm. “Probably made by Sheaumann for Laser Components on 100 mm wafer,” said Fraux. The conditioning unit uses an avalanche photodiode (APD) to acquire the laser beam after passing through two lenses, one transmitting and one receiving. “APD is probably made by First Sensor on 150 mm Wafer with 8-pin FR4 LLC Package and Die Area of 5.2 mm² (figure 14),” Fraux said.

APD is a high-speed photodiode that uses photonic multiplication to obtain a low noise signal. The APD achieves a higher S/N ratio than the PIN photodiode and can be used in a wide range of applications such as high precision rangefinders and low light level detection. From an electronic point of view, the APD requires higher inverse voltage and more detailed consideration of its temperature-dependent gain characteristics.

Figure 14: Avalanche Photodiode (APD)

In addition to the two units for laser and motion control, the control hardware also consists of the main board consisting of a Xilinx XA7Z010 SoC dual-core ARM Cortex-A9, a 32-bit STMicroelectronics SPC56EL60L3 microcontroller, and a power management system consisting of a Synchronous Step-Down Regulator from ADI, Dual channel smart high-side Power Switch from Infineon, triple monolithic step-down IC with LDO from ADI and a three-phase Sensorless Fan Driver IC from Allegro. The FlexRay protocol enables data communication. A FlexRay system consists of several electronic control units, each with a controller that manages access to one or two communication channels.

An estimate of the cost per volume >100K units/year of such lidar technology could reach $150, with a good percentage of it being related to the main unit board and the laser (Figure 15).

Figure 15: The disassembled laser scanner hardware

In a lidar project, the transimpedance amplifier is the most critical part of an electronic layout. Low noise, high gain, and fast recovery make the new devices ideal for automotive applications. To achieve maximum performance, designers must pay special attention to interfacing and integrating circuits, wavelengths, and optical-mechanical alignment. These integrated circuits meet the automotive industry’s most stringent safety requirements, with AEC-Q100 qualification.


https://www.eetasia.com/teardown-lessons-learned-from-audi-a8/