A full suite of parts includes components for complete radar systems, with features such as seamless integration with NXP’s S32R27x/37x automotive processing platform.
By Murray Slovick, Contributing Editor
The rise of automated driving has changed the landscape for radar, which is simply a method of using radio waves to determine the range, angle, and relative velocity of objects. In today’s vehicle safety systems, radar is used in conjunction with cameras, ultrasound, LiDAR, and other sensors to obtain information about a vehicle’s surroundings. Increased demand for both front-view and 360-degree surround-view sensing has led automakers to search for the best RF performance, power consumption, and sensor size based on the specifics of the application and the in-vehicle location.
Traditionally, automotive radar systems used frequencies in the 24-GHz unlicensed industrial, scientific and medical (ISM) band from 24.0 to 24.25 GHz, which is often called the narrowband (NB), having a bandwidth of 250 MHz. For automotive apps, Ultra Wideband (UWB), which is 5 GHz wide, also is currently available. However, due to spectrum regulations and standards developed by the Federal Communications Commission (FCC) and the European Telecommunications Standards Institute (ETSI), use of the UWB band will be phased out after January 1, 2022 in both Europe and the U.S.
Benefits of 77 GHz
In phasing out 24-GHz UWB, the regulating authorities have opened up frequencies for automotive radar in the 77-GHz band. One of the key benefits of 77 GHz is the wide bandwidth available—it provides up to 4 GHz of sweep bandwidth, which is much larger than the 200 MHz available in the 24-GHz NB.
Sweep is important because unlike the older, rotating radar systems, a frequency-modulated continuous-wave (FMCW) radar transmits a “chirp” that’s a frequency sweep across the bandwidth of the system. Objects in the path of the signal then reflect this chirp back. The difference between the frequency of the chirp coming out of the transmitter and the frequency of the received reflected signal is directly related to the distance from the transmitter to the object.
Smaller size is another advantage of 77-MHz systems. The wavelength of 77-GHz signals is one-third that of a 24-GHz system, so the total area needed for a 77-GHz antenna is one-ninth the size of a similar 24-GHz antenna.
Last week, NXP Semiconductor showed off the latest additions to its 77-GHz radar portfolio, the NXP MR3003 and TEF81x transceivers. The MR3003 is specifically developed for front or corner radar applications in automated driving, where high resolution and long-range capabilities are needed. The new range of NXP system components (Fig. 1) enables carmakers to match their requirements, and are said to be the industry’s only radar portfolio based on both BiCMOS and RFCMOS process technologies.
By implementing products in both silicon-germanium (SiGe) BiCMOS and RFCMOS technologies, NXP’s radar family is designed for automakers that are developing systems ranging from small, compact radar sensors through high-resolution imaging radar sensing applications. This helps lead to broad penetration of radar across the full range of car models.
NXP estimates that more than 50% of all car radar modules shipped in 2017 utilized its radar technology (Source: IHS  and Strategy Analytics [Q1 2016] market data).
The MR3003 is an automotive-qualified (temperature range is up to +125°C), single-chip, 76- to 81-GHz transceiver (Fig. 2). It incorporates three transmit and four receive channels. Using multiple MR3003 radar transceivers connected inside a single radar sensor enables the sensor to deliver high output power, low noise, and the scalability required to achieve high-resolution imaging. By way of review, the resolution of a radar distance measurement determines how far apart objects need to be before they’re distinguishable as two objects.
Scalability comes into play, because at level 4 and level 5, autonomous driving radar systems will be called on to track thousands of targets simultaneously for real-time sensing of the surrounding environment.
Other features include 4-GHz chirps utilized to achieve the MR3003’s high object resolution (NXP claims “best in class” separation of objects due to low phase noise and linearity), and long-range detection due to high output power and a low noise figure.
The MR3003 is complemented by the NXP S32R automotive radar processing platform, networking ICs, and power-management solutions. At the recently concluded Consumer Electronics Show (CES), the company used multiple MR3003 radar transceivers connected inside a single radar sensor to demonstrate an RF performance solution capable of tracking thousands of targets simultaneously. This radar scenario enables real-time sensing of the surrounding environment, essential for L4/L5 autonomous driving.
Also at CES, NXP employed a TEF810X RFCMOS radar transceiver and S32R274 processor to underscore performance, design, and low power consumption. With the TEF810X, the company showed that up to 12 to 20 sensors can be connected together around the car to provide a 360-deg. view (Fig. 3).
The TEF810X is a fully integrated, 77-GHz, RFCMOS automotive radar transceiver that enables critical safety applications such as emergency braking, adaptive cruise control, blind-spot monitoring, cross-traffic alert, and automated parking.
NXP’s S32R27x processors are 32-bit Power Architecture-based MCUs. The device family members are designed to address radar signal-processing capabilities combined with automotive microcontroller capabilities for generic software tasks and car bus interfacing.
The S32R27x is said to meet the high-performance computation demands required by modern beamforming (a digital technique that focuses the radar transmitter and receiver in a particular direction), and fast chirp-modulation radar systems by offering signal-processing acceleration together with a multicore architecture. It supports automotive safety applications that require a high Safety Integrity Level (ASIL, similarly MR003 offers ISO26262 compliant ASIL Level B safety), and adds security features to prevent unauthorized manipulations. The MCU incorporates compression technology, enabling users to minimize the amount of memory required for radar signal-processing tasks.
The MR3003 and TEF810x radar transceivers are sampling now, with production release expected later this year.