In order to better understand the hardware solution of the latest millimeter wave radar, let's first focus on the hardware topology of the cutting-edge ADAS/autonomous driving perception system.
First, the solid-state lidar, millimeter-wave radar, and camera sensors are clearly divided into three independent domains, and each domain has a separate domain controller (Sensor Domain Processor).
On the other hand, multiple sensors or radars of the same type are attached to a domain controller. For example, in the millimeter-wave radar domain, there are 2 groups of 6 radar transceivers. It should be noted that the latest automotive millimeter-wave radar supports cascade technology. It increases the number of transceiver antennas in a certain direction by connecting multiple transceivers in series. The synchronization of the domain controller enables the radar in this direction to have a larger visual field. Field angle and detection capability.
The 6 SRR/MRR medium and short millimeter wave radars are cascaded in groups of 3, and the 2 groups are respectively responsible for different detection directions. At the same time, the LRR long-range millimeter-wave radar is independent, because the forward-looking radar adopts a broadband high-resolution narrow beam mode, which is specially responsible for high-level security functions such as ACC and AEB.
Its data interface needs to meet the requirements of large bandwidth and low latency, so it directly links the fusion controller without going through the branch of the domain controller. Of course, this topology structure centered on the Control Fusion Unite can be extended to multiple domain controllers, and the structure is very flexible.
The spatial data obtained by different types of radars or sensors are fused and calculated in this unit, and finally a three-dimensional spatial map is established to realize ADAS functions such as safety warning, lane change, surround view and automatic parking.
77/79G Radar System Solution
A complete vehicle-mounted millimeter-wave radar transceiver module includes four parts: RF front-end (including antenna), digital front-end, digital processing DSP and power supply. Millimeter-wave radar is used as a front-mounted component of the whole vehicle, and the number of single-vehicle equipment is large, so the OEM is very sensitive to its cost.
In the early millimeter-wave radar solutions, due to the limitation of the radio frequency semiconductor process, the circuits were mainly constructed by separate devices, the performance and quality were not stable, and the cost could not be reduced. However, with the improvement of MMIC microwave chip technology and manufacturing process, different semiconductor companies have proposed integrated solutions with their own characteristics.