Automotive radar chipset bolsters ADAS appeal

-June 25, 2013

I spent an hour recently talking with Freescale about their new chipset for radar-based ADAS (Advanced Driver Assistance Systems) announced today. Freescale is hoping the integration and lowered BOM cost will appeal to a wider range of vehicle designers than the small number currently using ADAS in higher-end automobiles.

Being a newbie to such systems, I was impressed by the raw technology, such as 77GHz antenna connections directly to the multichannel Rx & Tx chips, and the highly integrated Qorivva MCU, which sports four PPC CPUs, two of which run in lockstep for redundancy checking. Here's a system block diagram:

This shows the maximum configuration of four Tx and 12 Rx channels, but lower channel counts can be implemented to best fit the application and cost goals. Apart from the MPC577xK MCU and three to seven MRD2001 family radar chips, only a handful of basic support circuitry is required (the grey blocks).

I asked about the RF aspects of the system, wondering if small horn antennas were needed, but no, simple PCB patch antennas do the job just fine. Speaking of PCBs, you can use a standard FR-4 stackup, adding a single low-loss top layer upon which the RF signals are routed.

The Qorivva MCU with dedicated radar processing functions

Another bit of technology that caught my eye was the FC (Fast Control) input on the Tx chip. This input performs a polarity inversion/180˚ phase shift on the 77GHz RF, allowing for modulation with unique digital sequences. The receive path can thus differentiate between multiple signals, including those from other vehicles.

Freescale told me that while they can supply low-level software, it will be up to the OEM to implement the higher functions of the system. They see application in front and side collision avoidance, adaptive cruise control, park assist, and other areas.

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