ActLight SA is the start-up company, founded in 2011 and based in Lausanne - Switzerland. At the CES this company is showcasing a disruptive technology in the field of light sensors.
Traditionally, photodiodes operate at constant reverse bias voltage giving photocurrent as output. Typically, this photocurrent is weak and requires further amplification. An amplifier introduces additional noise, which becomes crucial at low light conditions. Instead of using DC bias, the DPD operates at pulsed voltages: the applied voltage is switched from reverse to forward bias. This forward bias induces a large forward current after a time delay, so called triggering time, which depends on the light intensity. This way, we measure the delay time of the large forward current instead of the small photocurrent magnitude.
The video of the technology can be watched here: https://www.youtube.com/watch?v=xfhZtbZ7n1E
Due to the large output signal, the DPD does not require any amplifier, and it can be directly connected to digital circuits. Absence of the amplifier and its associated noise provides a great improvement in the device performance. Based on the standard CMOS technology, the DPD and its simple front-end circuits are integrated on the same chip. The absence of complex analog circuits allows to reduce silicon area and provides cost-effective solution.
Typical applications are sensors for wearable devices, mobile applications and LIDAR.
More information: www.act-light.com
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