mmWave Sensors for ADAS, Robotics, and Security

Created: July 11, 2022
Updated: October 10, 2024

Today’s electronics are becoming more integrated with the world around them thanks to ubiquitous use of sensors and HMI systems. Today’s suite of mmWave sensors come in IC form and module form, and both provide compact solutions for many systems, including robotics, UAVs, ADAS, and security. The most recognizable application of mmWave sensing falls into two areas: radar and wireless, specifically 5G and upcoming 6G systems.

Although these two areas are most recognizable, they are not the only areas of opportunity for mmWave engineers and systems designers. mmWave sensors are useful for other tasks like gesture recognition, occupant or object detection, vital signs measurements, and even imaging. In these application areas, mmWave transceivers and sensors are the technological enablers that systems engineers need to build their products.

If you’re designing systems that need a mmWave sensor, you’ll find multiple options on the market that enable diverse functionality for mmWave systems.

Example mmWave Sensors and Application Areas

There are multiple application areas for mmWave radiation and sensing beyond 5G and car radar, and some components are available that are tailored to specific systems in these areas. Other components are for general usage at mmWave systems, making them decent tools for research into new system design and architecture.

Below, I’ll explore some of the major commercializable areas where mmWave sensors are being used today, as well as where someone might find opportunities to build new products.

Automotive Radar

The first area is in automotive driver assistance systems (ADAS), where radar is used alongside multiple sensors (optical, ultrasonic, and short/long-range radar) for automobile safety. mmWave sensors operating at 24 GHz are used for short-range radar in vehicles for applications like blind-spot monitoring, obstacle detection, and collision avoidance. These short-range radars have been using the ISM band at 24 GHz or the ultra-wide band (UWB) from 21.65 to 26.65 GHz. However, the UWB band will become obsolete by 2022 thanks to US and European regulatory constraints.

Today’s wide field of view radars and long-range focused radars operate with 77 GHz carriers, the latter of which can provide range out to approximately 250 m. Commercial radar modules use center-fed patch antennas for transmission and reception of frequency-modulated continuous-wave (FMCW) chirped radar signals. The use of a center-fed patch antenna gives the required beam steering, directional detection, and wide field of view needed for these radars.

Drones and Robotics

UAVs and robots both need radar to “see” the world around them and track external objects in the environment. Drones and other robots, such as industrial or home robots, can operate at 24 GHz in the ISM band, or they can operate at 60 GHz for higher resolution applications. Just like with automotive radar, these systems need to fuse data from multiple sensors with sophisticated processing algorithms to make the most use of mmWave signals and sensors.

Security

This area is one that is still less well-known, but radar can be integrated into security systems for people counting, object detection, and object tracking. Smart infrastructure is a more general area where the mmWave sensors can be used for object detection and tracking. mmWave radars and sensors have been instrumental for bringing computation perception out to edge computing systems with a primary application being in security. These radars succeed where something like an optical solution (i.e., object recognition with a camera) fails simply due to cost and field of view; accurate optical object recognition at such a long distance requires sacrificing field of view, and it requires a more expensive optical assembly. mmWave radar and sensors in security camera systems create a useful object tracking solution.

High-Resolution and Imaging Systems

While mmWave emitters and receivers are very useful for detecting targets, these systems have typically not been effective for imaging. There are several reasons for this, primarily the need for high resolution beamforming. The challenging problem with beamforming in terms of systems design is the relationship between resolution and number of emitters. Higher resolution imaging requires more emitters, which in turn requires synchronization among multiple emitters to set a phase delay between broadcast signals for the desired propagation direction.

In order to get more signals synchronized across a large number of emitters, you would need to have multiple transceiver chips being synchronized by a lower frequency clock, ideally an intermediate frequency (IF) oscillator. This sync oscillator will only be available on certain components; this type of system is a cascade system due to the orchestration of wave emission from multiple components.

An example block diagram showing the Tx/Rx sync in a single mmWave sensor is shown below. Multiples of these block diagrams are placed in parallel and are synched with the same oscillator (LO) and clock (CLK). This gives you the multiplicity of emitters that are emitting in a phase synchronous fashion.

The other important factor in imaging is to deal with the massive amount of data that you generate in the system. Transmitting these data back to a system controller (usually an FPGA with appropriate IP) requires routing some very high data rate protocols; the state of the art in radar imaging system uses 10G or higher Ethernet for data transfer.

mmWave Sensor vs. Radar Receiver

What’s the difference between products marketed as radar transceivers and mmWave sensors? Frankly, there is not much difference aside from the application area they target, how signals are generated and used, and the number of features that are integrated into an mmWave component. Today’s radar modules will use a specialty radar transceiver for their particular application, where automotive radar transceivers are a great example. mmWave sensors will be marketed for more general applications like object and level detection, people counting and tracking, or other tasks.

The other main difference is the level of feature integration. Components targeting very specific applications will include those features needed for the application (both in terms of hardware architecture and firmware). Trying to fit a general purpose mmWave sensor into a more specific application may require supplementing with an external MCU or other component.

Some General Purpose mmWave Sensors

Texas Instruments IWR1642

The IWR1642 mmWave sensor by Texas Instruments is one example of a generall-purpose mmWave sensor that can also function as a radar transceiver. It includes 4 Rx channels and 2 Tx channels for directional control if needed. All features are programmable through an external MCU over standard interfaces (SPI, I2C, UART, GPIO) or a 2-lane LVDS interface for raw ADC data access. This sensor is designed for operation from 76 to 81 GHz and provides integrated FMCW signal processing capabilities for applications like security and industrial monitoring.

Texas Instruments IWR6843

The IWR6843 mmWave sensor IC from Texas Instruments is even more general-purpose than the previous component. This component targets applications in the 60 to 64 GHz range, such as functional safety applications and automation. This mmWave sensor includes an on-chip DSP block for advanced signal processing and hardware accelerator for FFT functions, filtering, and CFAR processing for object identification and tracking. There is also a plugin antenna module based on this component available from Texas Instruments (MPN: IWR6843ISK).

Infineon BGT24LTR11The BGT24LTR11 mmWave sensor from Infineon targets 24 GHz applications in a very small footprint. This component only uses 1 Tx and 1 Rx channel, so there is no directional control through beamforming with a single component. However, eliminating extra Tx/Rx antenna interfaces provides a much smaller footprint than other mmWave sensors or radar transceivers, so this could be used for a simple emitter/detector. Any application that requires small footprint, no directionality, and low power consumption at 24 GHz can benefit from this component.

The other option for this type of component is to implement beamforming of a highly stable, highly coherent 24 GHz signal through cascading. Unique MIMO systems are also possible with these components. Aside from the single Rx/Tx channel pair, the main advantage of these components is their temperature-driven frequency drift compensation through an input tuning voltage pin. This eliminates the need for a PLL/MCU to compensate for temperature drift.

Other Components to for mmWave Products

mmWave applications are still unfolding and frequencies are being pushed to higher limits. The applications listed above also need a range of other components to build a complete system. Some other components designers might need include:

Whether you need an mmWave sensor or an integrated radar transceiver, you can find the parts you need and keep up with all the newest component developments when you use the complete set of advanced search and filtration features in Octopart. When you use Octopart’s electronics search engine, you’ll have access to updated distributor pricing data, parts inventory, and specifications, and it’s all freely accessible in a user-friendly interface. Take a look at our RF devices page components for your next RF system.

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