CMOS self-powered monolithic light-direction sensor with digitalized output

Hongyi Wang, Tao Luo, Zhijian Lu, Hongjiang Song, Jennifer Blain Christen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We present a novel self-powered chip to detect the direction of incident light. This chip directly provides digitized output without the need of any off-chip power supply or optical or mechanical components. The chip was implemented in a standard 0.5 μm CMOS process. A microscale metal baffle was created by stacking all metal layers, contacts, and vias available in the process to produce on-chip shadowing. N-well/p+ photodiode arrays are located on both sides of the baffle to sense light. The photocurrent generated by a photodiode depends on the size of the photodiode and the shadowing. The shadowed area depends on the incident angle of the light. A current mirror circuit is used to compare the currents generated by the photodiodes on the opposite sides of the baffle and, consequently, provide a digital signal to indicate the incident light angle. Compared with the ideal linear digital light-angle detector with the same resolution, the presented sensor achieved the maximum error of only 2 deg over 110 deg test range.

Original languageEnglish (US)
Pages (from-to)2618-2621
Number of pages4
JournalOptics Letters
Issue number9
StatePublished - May 1 2014

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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