How AoP Technology Improves External Near-Field Sensing Applications

Millimeter wave radar provides a highly accurate sensing method for automotive and industrial applications, providing insightful object information such as distance, angle and speed, enabling smarter sensing solutions for detecting objects at ranges from a few centimeters to hundreds of meters.

Typically, radar sensors are mounted on a printed circuit board (PCB) consisting of a radar transceiver, antenna, power management circuit, memory, and interface peripherals. The antenna on the PCB requires a high-frequency substrate material, such as the silver-colored Rogers R03003 shown in Figure 1.

Antenna-on-package (AoP) technology eliminates the need for high-frequency substrate materials and reduces cost, manufacturing complexity and board space by approximately 30%. TI's AoP technology uses flip-chip packaging technology to place the antenna on a non-molded substrate, preventing the loss of the antenna through the molding material that reduces efficiency and causes stray radiation. Using a multi-layer substrate can further reduce the size of the board and make it easier to overlap the antenna and silicon die.

The AWR1843AOP device integrates the antenna directly onto the package substrate.

Using AoP technology can achieve the following advantages:

Reduce the overall size.

Reduce bill of materials costs.

Eliminate the need to design, simulate and tune antenna performance, reducing engineering costs and accelerating time to market.

Reduce power loss by shortening the wiring from the device to the antenna.

How AoP Improves External Near-Field Sensing Applications

Automakers are moving toward providing some automated features beyond ADAS, such as automatic door and trunk opening, which requires a high-resolution sensor to detect different types of objects to avoid collisions when opening doors and trunks.

TI's AWR1843AOP mmWave radar sensor is used for near-field sensing applications, providing three-dimensional detection through a low-power single-chip solution with integrated AoP technology. This highly integrated sensor is small enough to be installed in spaces such as door handles, foot pedals and B-pillars. In addition, the high range resolution of the AWR1843AOP enables it to detect objects of any size, shape or structure.

Detecting multiple static objects

The AWR1843AOP operates in a bandwidth of 76 GHz to 81 GHz with a range resolution of less than 4 cm. By combining a wide field of view with high range resolution, it can detect and distinguish multiple static objects simultaneously. As shown in Figure 3, the AWR1843AOP evaluation kit is mounted on a car door 43 cm above the ground, and the traffic cone is marked as a red cube in the graphical user interface because the car door will hit it when it opens. The metal pole farther from the sensor is marked as green because the car door will not hit it when it opens.

Detecting low-altitude objects

Door obstacle detection sensors require a solution with 3D vision capabilities to prevent collisions with objects below the sensor height. Other sensing technologies, such as time-of-flight and ultrasonic, may not be able to detect objects much below or above the sensor height, and they do not provide a reliable solution for detecting low-height objects such as bollards and curbs. Camera-based solutions can detect low-height objects, but are not reliable in adverse weather conditions such as rain and snow.

The AWR1843AOP device can detect low-height objects in both the azimuth and elevation planes. The mmWave radar sensor is also suitable in adverse weather conditions. Figure 4 shows the detection of a cinder block used as a low-height curb using the AWR1843AOP evaluation module (EVM).

Detecting objects with very small surface areas

Objects such as bicycles and shopping carts are difficult to detect due to their shape and structure. However, the AWR1843AOP’s high range resolution and wide field of view allow it to detect objects with very small surface areas.

Multi-model

The AWR1843AOP features a multi-mode programmable digital signal processor that allows you to reconfigure the same sensor for multiple applications. For example, you can use the AWR1843AOP device as an obstacle detection sensor for automatic door opening as well as a side-view radar sensor for detecting objects in blind spot areas while the car is in motion. This multi-mode nature can reduce system cost despite the implementation of multiple sensing applications. Figure 6 shows the use of a door obstacle detection sensor to detect a cyclist at a distance of 5m.

TI's AoP technology enables flexible placement of sensors in new locations, such as door handles. The 77GHz AWR1843AOP sensor accelerates time to market and reduces system-level cost for applications such as door obstacle detection, trunk obstacle detection, basic blind spot detection, and parking assistance.