Sunday, August 28, 2011

Samsung Patent Application Improves ToF Sensor Speed

Recently published Samsung patent application US20110198481 talks about speeding up a ToF imager based on in-phase/out-of-phase light pulses measurement. The sensor includes a detection portion and a transfer portion separating the signal between two floating diffusions:

The detection portion is a pinned photodiode, while the transfer part consists of photogate, transfer gates Tx1 and Tx2 and floating diffusions FD1 and FD2 separately accumulating in-phase and out-of-phase signals. The photodiode is made has few different doping areas to create a potential stairs and speed the charge transfer to the photogate:


  1. US guy's idea? Doping profile modulation is a common sens and used in CCD pixel design.

  2. The idea belongs to guys on the patent application. Just look it up. I am not even sure I know those guys or not. There are several parallel efforts going on in the behemoth Samsung.

    Meanwhile, yes, laterally graded or stepped doping profiles to enhance lateral charge transfer are not new. Not sure if this particular configuration in-total is new or not. With a transverse taper and common first "photogate" 1720 between the pinned photodiode (also a photogate) and TX1 and TX2 it might be new.

    A different device, reduced to practice, will be reported at the 2011 IEDM by members of our team at Samsung.


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