Automotive radar, a key component of advanced driver assistance systems (ADAS), is playing an increasingly vital role in improving road safety – especially as other sensing technologies (such as cameras and lidar) face important limitations. One of the most promising advancements is the development of 140 GHz radar, which is to complement the 60 GHz (in-cabin) and 77 GHz (environmental perception) radar systems currently in use. With its high resolution and compact design, 140 GHz radar promises to offer robust sensing – both inside and outside the vehicle – at a fraction of the cost of lidar.
Technology experts at imec estimate that this new radar flavor could be integrated into the automotive sensor suite by the early 2030s, unlocking exciting use cases such as automated valet parking and advanced driver monitoring. But several technical and regulatory challenges must be addressed before the technology can reach full commercial potential.
This article outlines the necessary steps for bringing 140 GHz radar to market and examines how its development could act as a catalyst for rethinking the overall design of automotive (sensing) systems.
A marvel of (sensor) technology
Nearly 150 years after Carl Benz first hit the road with his ‘Benz Patent-Motorwagen’, cars continue to be technological marvels. They come equipped with arrays of up to one hundred sensors, and high-end models can feature even twice that number. On the one hand, this automotive sensor suite plays a critical role in optimizing engine performance by continuously monitoring key parameters in the engine control unit (ECM) – such as air flow, fuel injection, and ignition timing. In addition, it includes camera, lidar, radar, and ultrasonic technologies to enhance road safety and driving comfort.
Figure-1: Example configuration of an automotive sensor suite supporting advanced driver assistance (ADA). Source: imec.
Image sensors (i.e., cameras) are invaluable to car manufacturers. They act as a powerful extension of the human eye, recognizing traffic signs, and enabling rear-view and surround-view functions to assist with parking and maneuvering.
Lidar (light detection and ranging) sensors generate high-resolution maps of a vehicle’s surroundings, allowing for accurate perception and response. They are crucial for applications such as pedestrian detection, monitoring complex overtaking maneuvers, and detecting obstacles ahead of the vehicle.
Ultrasonic sensors are particularly useful at low speeds and in close-range scenarios, aiding in safe parking and blind spot detection.
Yet, while each of these technologies enhances a car's perceptive capabilities, they also come with limitations. Cameras struggle in low light or excessive brightness and require extensive, costly processing to convert video (pixels) into usable data. Lidar’s laser beams are easily scattered or absorbed in adverse weather conditions, such as heavy rain, fog, or snow. Moreover, lidar systems are expensive to build, acquire, and maintain. And, finally, ultrasonic sensors offer limited value over longer distances.
This is where radar technology steps in, offering robust, reliable, and long-range sensing – even in harsh weather conditions, and at a fraction of the cost of lidar.
Modern cars are already equipped with multiple radar sensors, often working in conjunction with camera technology to support advanced driver assistance features such as adaptive cruise control, collision warning, and lane keeping assist. But radar is also set to become an increasingly interesting technology option for in-cabin sensing applications. Think of driver monitoring and detecting the presence of children or pets in a parked vehicle, even if they are hidden (like under a blanket in the backseat).
The advantages of tapping into the 140 GHz band
Current automotive radar systems operate in two frequency bands: 60 GHz for (first-generation) in-cabin applications and 77 GHz for out-of-cabin use cases. This separation helps minimize interference, as radar systems using the same frequency can disrupt each other’s signals.
In parallel, however, the automotive industry has also started to explore the 140 GHz band. One factor driving this exercise is that the 60 GHz band is also used for wireless local area networking (WLAN) and point-to-point communication, hindering automotive radars’ performance.
And tapping into the 140 GHz frequency offers even more advantages, including:
- Higher resolution: enabling the detection of smaller objects and improving the detection of objects at various distances and angles (e.g., distinguishing between multiple passengers in a vehicle).
- Smaller antennas: this is particularly beneficial for automotive design, where compactness and maintaining a sleek appearance are critical.
Each of these capabilities will be essential for enabling a new range of use cases, including automated valet parking and advanced driver monitoring – features consumers are willing to pay a premium for in a highly competitive, high-pressure market.
Figure-2: Comparing the resolution of 79 GHz and 140 GHz radar at a 30 m range (with a radar aperture of 15 cm x 15 cm). Source: imec.
Comparing 140 GHz radar with UWB technology for in-cabin sensing
Ultra-wideband (UWB), a short-range 8 GHz wireless technology, is already used in premium automotive features such as secure keyless entry. But its potential goes much further. UWB's fine-range capabilities also make it particularly suitable for in-cabin sensing applications.
So, how does this technology compare to 140 GHz radar?
Ilja Ocket explains: “The main difference between 140 GHz radar and UWB lies in their signal properties. The longer wavelength of a UWB signal makes it more difficult to achieve consistent coverage throughout a car’s interior, often requiring the installation of multiple anchors. In contrast, the higher frequency of 140 GHz radar offers greater resolution and accuracy, making it ideal for complex use cases – using just a single sensor.”
Does this mean that 140 GHz radar will eventually replace UWB in the automotive market?
“Not quite,” says Ocket. “At imec, we believe both technologies will coexist, addressing different needs, but complementing each other to enhance vehicle safety and comfort. UWB comes with the benefit that OEMs are already familiar with the technology. Moreover, it can build on existing (keyless entry) infrastructure – thus offering an important cost advantage. In contrast, 140 GHz radar, with its higher resolution, could become the preferred technology option for monitoring tasks where precise measurements of both the angle and distance between multiple occupants or objects are crucial.”
“Actually, we’re far from reaching a point where automotive sensor suites are fully saturated. The real challenge is adding (new) sensor modalities without significantly increasing the sensor suite’s overall price tag. This is why, for both radar and UWB implementations, the automotive industry will continue to require sensors to be fabricated using CMOS-based technologies that leverage standard, cost-effective chipmaking processes.”
Bridging the gap to commercialization: the challenges
Commercialization of 140 GHz automotive radar solutions is expected by the early 2030s. While the technology has great potential, several hurdles must be overcome before it can be integrated into commercial vehicles.
Importantly, the main technological challenge isn’t related to semiconductor limitations – as 140 GHz radar systems can still leverage standard CMOS technology (as opposed to even higher-frequency solutions that require the use of more expensive, exotic technologies such as indium phosphide). This allows the industry to benefit from advanced system-on-chip integration, nanometer-scale design and improved power efficiency – all while keeping production costs low, which is essential for mass-market adoption.
The bigger challenge lies in the realm of physics. As radar systems transition from 60 GHz and 77 GHz to 140 GHz, the same amount of transmitted power covers a shorter distance. In other words, achieving the same sensing range at higher frequencies requires more power, which is technically difficult to realize. Hence, depending on the range desired by OEMs for 140 GHz sensors, the state-of-the-art will need to advance towards co-packaged or integrated III-V front ends combined with CMOS technology.
This challenge is further compounded by the integration of radar systems into the vehicle, which causes a significant signal loss. Although transparent materials are used already to allow radar signals to pass through more easily, this issue worsens at higher frequencies. New material solutions are thus required that are not only transparent to 140 GHz, but that are also strong, durable, and visually appealing.
Why regulation will be key to the commercial success of 140 GHz automotive radar
Beyond technical challenges, the lack of (unified) spectrum regulation is another obstacle to the commercial adoption of 140 GHz automotive radar systems.
Ilja Ocket: “Spectrum regulations for the currently used 76-81 GHz frequency band vary from country to country. This hinders the global commercial introduction of automotive radar, as OEMs need consistent standards to sell their cars worldwide. As such, to avoid repeating this problem with 140 GHz automotive radar systems, achieving global standardization is key.”
While advisory groups are already working on regulatory recommendations, particularly for in-cabin applications, Ocket believes this process needs to be accelerated.
“As we move towards permitting the use of 140 GHz for in-cabin applications, we should leverage this momentum to secure spectrum regulation for higher energy levels, enabling valuable applications for external sensing too.”
“Improved road safety depends on the availability of affordable, smart cars – and 140 GHz automotive radar is crucial to this. However, this vision can only be realized if regulation steps up its game,” he concludes.
The importance of continued research in driving 140 GHz CMOS radar
Although commercial 140 GHz (automotive) radar solutions are not yet available, semiconductor leaders like TSMC and GlobalFoundries are already deeply engaged in their development. In parallel, research efforts continue to advance as well – focusing on areas such as interference management, technology benchmarking, and new radar design principles.
Interference management includes one major area of research. The research community strongly advocates for a standardized modulation scheme within the 140 GHz band to mitigate interference from the outset. Building on its expertise in developing 77 GHz automotive radar systems, this is an area where imec plans to play a leading role.
Another crucial focus domain is the neutral benchmarking and evaluation of semiconductor technology platforms – including the 22 nm FD-SOI and 16 nm FinFET flavors, which are considered good candidates to support the development of 140 GHz automotive radar systems. Here, imec's expertise in the objective evaluation of semiconductor technologies should once again help the industry to select the most suitable technology options.
Finally, a third important research challenge is the development of distributed and coherent radar architectures, where radar units operate coherently – sharing data and being centrally coordinated – rather than functioning in isolation. This approach could result in smaller, more efficient, and cost-effective radar systems with lidar-like angular resolution. Again, drawing on its expertise in 77 GHz radar design, imec can contribute significantly to this area – especially in the development of the underlying chiplet architectures for data processing.
140 GHz radar: a catalyst for a radically new approach to automotive (sensing) design
The rise of software-defined vehicles calls for a fundamental shift in how cars are developed. Simply adding hardware and layering new software is no longer sufficient. Instead, car manufacturers must design and build safety-critical products that are increasingly electronic, with systems built from the ground up to support complex and safety-critical applications. However, the automotive industry lacks experience in this type of comprehensive overhaul.
Imec believes that developing 140 GHz automotive radar systems should be a part of this transformation. It presents an ideal test case for the accelerated development of a new sensing modality, and its integration with – or even within – camera modules.
Figure-3: Imec’s 140 GHz radar demo platform. Source: imec.
Imec's unique position in 140 GHz automotive radar development
Imec leverages decades of expertise in sensor technology and CMOS scaling to advance the development of 140 GHz automotive radar systems. With a proven track record of driving complex innovations in the semiconductor industry, imec has historically collaborated with foundries and Tier-2 providers. Now, it is expanding its focus to the automotive sector, working directly with automotive OEMs and Tier-1 suppliers – who often possess visionary ideas about the future of automotive technology, but have traditionally lacked access to core component developers.
Ilja Ocket: “Imec has a rich history of driving breakthrough chip innovation through its unique open innovation R&D model, often involving significant investment and risk in areas where traditional suppliers may be more cautious. Aiming to replicate this success in the automotive industry, imec seeks to bridge the gap between automotive applications and core technologies, from chips to system-level solutions. As one of the few global organizations equipped to shape this rapidly evolving landscape, imec is well-positioned to lead the way.”
Conclusion
140 GHz automotive radar has the potential to transform the driving experience by offering high-resolution sensing at an affordable price, enabling services like automated valet parking and advanced driver/passenger monitoring.
While this technology will be pivotal in making vehicles smarter, safer, and more efficient, ongoing research into key technological advancements is essential. Additionally, proper spectrum regulation will be crucial to democratizing the technology and ensuring its widespread adoption.
