Analog-to-digital conversion for image sensor with non-destructive read pixel

摘要

Methods and systems for analog-to-digital conversion applicable to an image sensor, such as a CMOS image sensor, in which pixels can be readout non-destructively, and wherein a non-destructive pixel read may be used to provide a coarse analog-to-digital conversion such that information can be stored, and the stored information is then applied in a fine analog-to-digital conversion during a subsequent actual pixel read.

主权项

1. A method for analog-to-digital (A/D) conversion of a pixel signal readout of an image sensor pixel, the method comprising:
performing a coarse A/D conversion of a first signal readout non-destructively from the image sensor pixel, the coarse A/D conversion generating a coarse signal comprising at least one bit, the first signal representing photocharge integrated in the image sensor pixel over a first time interval; storing information representing the coarse signal; performing, based on the stored information, a fine A/D conversion of a second signal readout from the image sensor pixel, the fine A/D conversion generating a fine signal comprising at least one bit, wherein the second signal represents a combination of the photocharge integrated in the image sensor pixel over the first time interval and photocharge integrated in the image sensor pixel following the non-destructive readout of the first signal; and wherein at least one of the at least one bit of the coarse signal has a binary weight that is more significant than the most significant bit of the fine signal, and at least one of the at least one bit of the fine signal has a binary weight less significant than the least significant bit of the coarse signal.