ADAS requires further upgrades, TI’s second-generation single-chip millimeter-wave radar takes the lead

“TI’s latest second-generation 77 GHz single-chip millimeter-wave radar, the AWR2944, is the industry’s first single-chip angular radar sensor to help automakers meet these safety regulations while offering a small form factor (smaller than current millimeter-wave radar sensors) about 30% smaller) provides excellent RF performance. The AWR2944 sensor integrates four transmitters with 33% higher resolution than existing millimeter-wave radar sensors, enabling vehicles to detect obstacles more clearly and avoid collisions.

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In November 2020, with the release of the “Intelligent Vehicle Development Roadmap 2.0”, China will officially enter the first year of autonomous vehicles in 2021. Most of the new cars launched by a large number of car manufacturers are equipped with automatic driving or assisted driving functions. At the same time, with the emphasis on safety, more and more car manufacturers provide a variety of sensor fusion ADAS solutions including image sensors and millimeter-wave radars.

Cai Zheng, general manager of Texas Instruments (TI) China Automotive Business Department, said that while autonomous driving brings new opportunities, there are still four challenges. The first is the constraints of national regulations, the second is the requirements of functional safety, and the third is the launch of products. The fourth is the cost-effectiveness of the system.

How to tackle the four major challenges of ADAS

TI has been supporting safe car driving from the ground up, starting with airbags and body stabilization systems four decades ago. Now, as ADAS systems have transitioned from luxury cars to mid-range and even entry-level cars, TI is working hard to make Electronic systems more affordable and practical through semiconductor technology, so that more people can enjoy the benefits of technology.

Cai Zheng introduced that for ADAS active safety applications, TI can provide three product solutions, including perception (millimeter wave radar sensor), processing (TI high-performance TDA4x automotive processor) and communication (SerDes) and other three aspects of technology, In addition, there are high-efficiency power supplies that support the work of each part of the system, so as to provide customers with a more complete solution.

For example, Keith Ogboenyiya, Senior Vice President of Marketing at TI, in “7 Ways Semiconductor Technology Accelerates the Future Development of Automotive Technology”, there are three trends that are closely related to safety, including:

FPD-link serializers and deserializers transmit uncompressed video data within automotive systems, enabling the deployment of higher-resolution cameras for adaptive driver assistance systems and displays.

A portfolio of automotive-qualified ICs, including high-precision radar SoCs, powerful processors, and reliable power management products, helps build high-performance ADAS.

TI has a broad portfolio of automotive compliant ICs with associated functional safety documentation to help engineers achieve the automotive safety integrity levels required for their systems for a safer driving experience.

Cai Zheng said that TI’s biggest advantage in the automotive field is that it has a wide range of product lines, which are currently close to 8,000 products, and the number of products is increasing every year. In addition, in order to meet the surging demand for chips in the automotive industry, TI is carrying out intensive capacity expansion plans.

TI upgrades single-chip millimeter-wave radar products

Cai Zheng also introduced new regulations made by the United Nations in Regulation No. 79, which clarified the new requirements for the safety of ADAS steering systems for new motor vehicles. For the updated content of this part, please refer to Bhavin Kharadi et al. As described in the article New NCAP Radar Requirements to Know”, in general, the minimum distance and minimum operating speed for radars in blind spot detection and lane change assist are specified, which imposes new requirements on the radar RF chip, resolution , the detection distance, processing speed, processing accuracy and other technical indicators should be further improved, while taking into account the factors of functional safety.

TI’s latest second-generation 77 GHz single-chip millimeter-wave radar, the AWR2944, is the industry’s first single-chip angular radar sensor to help automakers meet these safety regulations while offering a small form factor (smaller than current millimeter-wave radar sensors) about 30% smaller) provides excellent RF performance. The AWR2944 sensor integrates four transmitters with 33% higher resolution than existing millimeter-wave radar sensors, enabling vehicles to detect obstacles more clearly and avoid collisions.

Jiang Hong, director of embedded product systems and applications in TI China, introduced the advantages of AWR2944 in detail.

First of all, let’s review the development history of TI’s millimeter-wave technology. The project was established in 2010, and TI’s prestigious Kilby Laboratory began to do preliminary development. The first single-chip CMOS millimeter-wave radar transceiver was officially launched in 2015, and an SoC integrating digital and RF functions was officially launched in 2016, and mass-produced in 2017. And now after a lapse of 5 years, the second-generation chip was officially released.

As shown in the figure, TI’s millimeter-wave radar currently covers a rich product portfolio, with different RF frequencies, different numbers of transceivers, and different integration levels, so as to deal with various scenarios.

AWR2944

AWR1843

Generally speaking, this series of devices includes four main modules: RF/analog front-end subsystem, BIST subsystem, DSP subsystem and main control subsystem. The composition is highly integrated, and among these four parts, three subsystems have achieved important updates.

In this, the RF/analog front-end subsystem, including RF and analog circuits: synthesizers, power amplifiers (PAS), low noise amplifiers (LNA), mixers, intermediate frequency (IF) links and analog-to-digital converters (ADCs) ). The subsystem also includes a crystal oscillator, temperature sensor, voltage monitor, and general-purpose ADC. The AWR family of devices uses a complex baseband architecture that provides in-phase (I-channel) and quadrature (Q-channel) outputs. Compared with the previous generation product, there is one more transmitting interface, thus achieving 4 transmissions and 4 receptions, with a maximum angular resolution of 0.1° to meet the new requirements of angular radar safety regulations.

A closed-loop phase-locked loop (PLL) achieves 0.0001% linearity and high-accuracy frequency modulation, helping to improve range accuracy.
The FM bandwidth has been increased from 4GHz to 5GHz, enabling more accurate detection of objects in the centimeter range.
Sophisticated receiver architecture enables detection of jammers or non-jammers in dense sensor environments.

The built-in self-test subsystem, also known as the BIST subsystem, includes the digital front end, the ramp generator, and an internal processor that controls and configures the low-level RF analog circuits and registers for the ramp generator. (Note: The processor is TI programmed for RF calibration needs and BIST/monitoring functions, but it is not directly available to the user.) The digital front end is responsible for filtering and decimation of the raw ADC output and provides it at a programmable sample rate Final ADC data sample.

The DSP subsystem includes a TI C66x DSP clocked at 360MHz for radar signal processing, usually raw ADC data. The DSP is user programmable and has complete flexibility in use. Compared with the previous C674x DSP, the performance is stronger and the energy efficiency ratio is better. Jiang Hong pointed out that with the continuous development of millimeter-wave radar technology, many algorithms are becoming more and more mature, which is why AWR2944 integrates a new hardware accelerator version 2.0, which can achieve more efficient radar preprocessing. In addition to this, the storage space for radar data has also doubled to 2.5MB to meet higher data demands.

A fully programmable DSP enables customers to implement proprietary algorithms and build innovative solutions to address radar performance challenges. Advances in research around algorithms can improve performance in several key areas, such as:

Mitigation of interference: As more and more vehicles adopt radar technology, the problem of interference between radars is becoming more and more serious. In this context, innovative algorithms for detecting and mitigating interference are an active area of ​​research and signal processing algorithm development.

Improved detection algorithms: Emerging applications of radar, including the ultimate field of view for fully autonomous driving, require improved algorithms related to object detection, ground clutter removal, and minimizing false detections to ensure stability.

High Resolution Angle Estimation: One of the main challenges associated with radar is the limited angular resolution. Several advanced angle estimation algorithms beyond traditional beamforming can improve angular resolution, including signal classification (MUSIC) and signal parameter estimation via rotation-invariant techniques (ESPIRIT).

Clustering and object classification algorithms: This is another active area of ​​research and algorithm development, especially object classification algorithms that require the use of high-resolution radar point clouds and identification of pedestrians using micro-Doppler techniques.

The main control subsystem includes an ARM vehicle-grade Cortex-R5F processor with a main frequency of 300MHz, which is programmable by the user. The processor controls the overall operation of the device, handles communication interfaces, and implements higher-level algorithms such as object classification and tracking. The processor can also run AUTOSAR systems. The functional safety MCU that supports lockstep computing also comes with HSM and is equipped with a larger RAM, making the controller more powerful and safer, so as to meet more stringent vehicle-level functional safety and information security requirements. And, in order to cooperate with the concept of domain control, new Ethernet and CSI2 interfaces have been added.

The overall package size of the chip is 12 mm × 12 mm, which is 1/3 smaller than that of the current millimeter-wave radar of the same level. It adopts the popular flip chip BGA package for vehicles, which is easy to assemble and has better heat dissipation and EMI performance.

Jiang Hong said, “In addition, the unique hardware configuration of this new sensor provides Doppler Division Multiple Access (DDMA)-based signal processing capabilities, which can sense oncoming traffic at a detection distance 40% farther than before. Vehicles.”

Jiang Hong added that TI’s millimeter-wave radar sensor has built-in various self-calibration modules to ensure accurate operation under any voltage and temperature conditions, thereby achieving better robustness.

In addition to the chips, TI also offers part of the SafeTI Design Suite to help developers implement ISO26262 ASIL B chip-level functional safety as well as ASIL D system-level safety in their applications.

China becomes the largest market for millimeter-wave radar

With the world’s largest automobile production and sales country, my country’s automobile industry is also undergoing rapid upgrading. The development of electrification, electrification and automation ranks among the top in the world. It is believed that my country will become the world’s largest forward radar market in the near future.

At the same time, millimeter-wave radar technology is also evolving rapidly. Jiang Hong predicts that sensor fusion will evolve from today’s 5 millimeter-wave sensors to 8. TI’s highly integrated and cost-effective products are very suitable for this market trend.

In order to better serve Chinese customers, TI’s official website provides detailed product information, SDK development tools, development boards, training materials, a continuous and unified code system, and a series of support from the engineer community. “Some customers may find it difficult to get started with DSP, but after a few months of familiarity, they will get started quickly. At the same time, TI products have always adhered to compatibility and heritage, and customer loyalty will be better.” Jiang Hong said.

“TI has always maintained close contact and cooperation with Tier1 and OEMs, and constantly discussed the new architecture of the central gateway and autonomous driving, as well as the upgrade of the in-vehicle bus system, to meet market needs through new technologies.” Jiang Hong said.

As shown on TI’s official website, companies including Aoku, D3, Inzinious and others have joined the TI mmWave ecosystem, providing a one-stop third-party service network from evaluation to Turnkey to mass production.

For wider applications

Cai Zheng said that the current cascaded millimeter-wave radar technology has not been fully developed, and it is believed that with the development of the millimeter-wave radio frequency front-end, there will be new development space for intelligence.

Secondly, AOP (Antenna on Package) is also another major innovation in the development of millimeter-wave radar. Jiang Hong said that because AOP technology is more integrated and more convenient to design, it is welcomed by manufacturers, but due to its limited antenna size, it is mainly used in some applications with large viewing angles and short distances, such as parking assistance and other applications. Alternative to ultrasonic radar applications.

DMS (Driver Monitor System) system is another popular safety standard added in recent years. Millimeter-wave radar can not only detect the presence of people, but also monitor the breathing and heartbeat of the human body through the centimeter-level monitoring level. Accurately determine the characteristics of life and health.

In addition, TI’s millimeter-wave sensors have been used in applications including the detection of baby leftovers in the car and the automatic opening of the trunk. With the release of the second-generation millimeter-wave radar, more accurate identification and higher processing performance can be used. Add more features to your vehicle, including air gesture recognition.

In addition to automobiles, TI is also introducing millimeter-wave radar technology into broader industrial market applications, including applications such as electronic fences, AGV navigation, and personnel detection, thereby expanding the market application of millimeter-wave technology.

As Keith said, we all know that the automotive industry is evolving rapidly, and today’s cutting-edge technology may become obsolete tomorrow. Semiconductor technology helps automakers create future-ready vehicles by removing barriers, reducing cost and complexity, and meeting safety requirements.