Ultrasonic ToF Sensors Boast Of Millimeter Precision

Chirp Microsystems’ CH-101 and CH-201 are heralded as the world’s smallest, lowest-power ultrasonic time-of-flight (ToF) sensors. As per their maker, they deliver the most accurate range measurement regardless of target size or color and are immune to ambient noise. Unlike optical ToF sensors, they work in direct sunlight.


Features include:

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  • Precise, low-latency range measurements at sample rates up to 100 samples per second with position noise below 1 mm
  • Desirable for always-on sensing applications such as human presence, motion and activity sensing at power levels as low as 15 microwatts
  • Detect objects over a field-of-view up to 180° — enabling a single sensor to support room-scale sensing
  • Detect objects of any color, including optically transparent ones — enhancing object detection
  • Ensure eye-safety — contrasting with laser-based IR sensors


The CH-101 and CH-201 measure range by emitting an ultrasonic “chirp” and then listening for echoes returning from targets in the sensor’s field-of-view. Each echo travels at the speed of sound, and an echo’s ToF provides a precise measure of the range to a corresponding target.


Chirp’s CH-101 and CH-201 are the first commercially available microelectromechanical systems (MEMS)-based ultrasonic ToF sensors. Measuring 3.5 mm x 3.5 mm, they integrate a MEMS ultrasonic transducer with a custom low-power CMOS system on a chip (SoC). Like a MEMS microphone, the CH-101 and CH-201 are offered in a 3.5-mm LGA package, operate on a single 1.8V supply, and have a I2C interface. An integrated microprocessor enables always-on operation for wake-up sensing applications and total current consumption is 8 µA when measuring 1 sample per second. The CH-101 has a maximum sensing range of 1 m, and the long-range CH-201 has a maximum range of 5m.


Chirp Microsystems

Berkeley, CA


[email protected]

[email protected]


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