Additional Key Requirements in Automotive Radar
As mentioned in the beginning, besides a superior radar signal processing performance, other aspects like functional safety, low power and smaller sensor size are gaining importance in Automotive. Radar sensors are providing safety-critical commands to chassis systems like anti-lock braking, electrical power steering or active suspension that impact the dynamics of a car. E.g. a false positive autonomous emergency brake command can be fatal and hence is rated as safety critical. A power efficient implementation helps to reduce carbon dioxide emissions, simplifies the thermal design of the sensor and may allow using cheaper housing material. Furthermore a low power design makes it easier to reduce the form factor of the sensor due to relaxed power dissipation constraints.
Example of a Radar Capture and Processing Hardware
Now let’s look at an actual example that is based on the AFE5401-Q1 and the TDA3xR System-on-Chip (SoC) from Texas Instruments as depicted in Figure 4. This exemplary implementation has 4 receive channels. The TDA3xR device family facilitates up to 8 receive channels allowing the implementation of a scalable set of radar sensors.
Figure 4: System Block Diagram for Radar Baseband Processing (Example). Click image for full resolution.
Both devices are or will be Automotive qualified and are optimized for radar applications. The AFE5401-Q1 is a high-performance analog front-end with 4 identical channels supporting simultaneous conversion. Each channel comprises a low-noise amplifier (LNA), an optional equalizer, a programmable gain amplifier (PGA) and an anti-aliasing filter followed by a high-speed 12-bit analog-to-digital converter (ADC) at up to 25 MSPS per channel. The exhaustive pre-conditioning considerably reduces the need for additional external components. The equalizer can compensate range dependent losses.