Chirp Adds Sonar-on-Chip to ToF Battle

Article By : Junko Yoshida, EE Times

Whether they appear in drones, robotic vacuums, VR/AR headsets or smartphones, sensors are proliferating in consumer systems to capture "accurate range and position measurement" information. Chirp Microsystems is adding its new MEMS-based ultrasound chip to the growing ToF battle.

MADISON, Wis. — Whether they appear in drones, robotic vacuums, VR/AR headsets, smartphones or cars, sensors are proliferating in consumer and industrial systems, to capture “accurate range and position measurement” information. 

Depth information is critical in an imaging world when things are fast transitioning from 2D to 3D sensing. Knowing accurate distances, for example, can augment position tracking in VR/AR headsets, and prevent robotic vacuum cleaners from running into walls or objects.

Although the market has already seen time-of-flight (ToF) sensors built on different technologies — such as IR and optical — Chirp Microsystems believes its new MEMS-based millimeter-sized ultrasound chip will become an effective alternative to the competition. Chirp boasts that it operates at ultra-low power with high precision range. It stands up to harsher environments while working both in total darkness and under the full sun, according to the company.

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Time of Flight Sensor Shipment in 2014-2021 (Q4 2017 update)

(Source: IHS Markit)

IHS Markit, currently preparing a report on ToF sensors, told EE Times that shipments “started to become relevant in 2016,” and then growing quickly. The market research firm predicts annual shipments to expand to 600 million units in 2019.

Michelle Kiang, Chirp’s CEO, first talked to EE Times earlier this year about her Berkeley, Calif.-based startup and its ultrasound sensing technology. Since then, “We’ve been busy adding a new product — a longer range sensor device (whose operating range extends to 5 meters) and the development of sensing solutions including software and system integration,” Kiang said. Chirp’s ultrasonic ToF sensors, the CH-101 and CH-201, are both sampling today.

How does Chirp stack up?
Manuel Tagliavini, principal analyst for MEMS and sensors at IHS Markit, told us, “The Chirp solution has its working principle based on a reflected ultrasonic wave, while the standard ToF devices are based on the measurement of the time a laser pulse requires to be reflected.”

Depending on its final application, the ultrasonic solution has strengths and weaknesses, he noted. For example, the wider field of view enabled by the Chirp’s piezo technology is advantageous for IoT appliances like the Amazon Echo, in sensing the user’s presence in a room, he said. But an ultrasonic solution applied to the AF system for cameras, for example, Tagliavini said, provides a general scene distance without necessarily measuring “the single details and object’s distance.”  

Michelle Kiang

According to Chirp, its ultrasonic ToF sensors offer 180-degree of Field of View (FoV), compared to the 20-25 degrees offered in IR-based solutions. Kiang told us that while IR-based ToF sensors are mainly used for front-facing applications, ultrasonic sensors are more flexible when designed into a system. “You can install it in a non-front facing panel and you can still see a lot,” Kiang said.

Comparing Chirp’s solution with optical ToF sensors, Jean-Christophe Eloy, President & CEO, at Yole Développement, agreed its main advantage is in the viewing angle. “The field of view of ultrasonic solutions is much larger than optical solution. The price is low, so it is easy to integrate multiple sensors.” He believes the ultrasonic solution, initially, “will be used for applications where optics is difficult.”

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