Analogue to digital converter for image sensor readout
AssigneeTeledyne Innovaciones Microelectronicas Slu
InventorsJose Angel Segovia de la Torre, Ana Gonzalez Marquez, Rafael Dominguez Castro, Alexander Charlet, Alberto Villegas
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Abstract
An analogue to digital converter for converting the analogue output of a dual conversion gain pixel of an image sensor. The dual conversion gain pixel is operable to sequentially output a reset pixel value and a signal pixel value sequentially with both a first gain and a second gain different to the first gain. An image sensor comprising the analogue to digital converter, a system comprising the image sensor and a method are also described herein.
Claims17
An analogue to digital converter for converting the analogue output of a dual conversion gain pixel of an image sensor, wherein the dual conversion gain pixel is operable to sequentially output a reset pixel value and a signal pixel value sequentially with both a first gain and a second gain different to the first gain, wherein the analogue to digital converter comprises:
- analogue storage for storing the reset pixel value output with the first gain;
- a converter stage arranged to sequentially sample a first analogue input indicative of a reset pixel value of the dual conversion gain pixel and a second analogue input indicative of a signal pixel value of the dual conversion gain pixel, wherein the converter stage is configured to sequentially sample the first input and the second input and output a digital value indicative of a difference between the first input and the second input;
- and
- circuitry configured to sequentially provide the reset pixel value output with the second gain as a first input to the converter stage and the signal pixel value output with the second gain as a second input to the converter stage such that the converter stage sequentially samples the first and second inputs and outputs a first digital value indicative of a difference between the reset pixel value output with the second gain and the signal pixel value output with the second gain, and
- wherein the circuitry is further configured to provide the reset pixel value output with the first gain and stored in the analogue storage as a first input to the converter stage and the signal pixel value output with the first gain as a second input to the converter stage and wherein the converter stage is configured to sample the first and second inputs and output a differential signal indicative of a difference between the reset pixel value output with the first gain and the signal pixel value output with the first gain.
A method of an analogue to digital converter for converting the analogue output of a dual conversion gain pixel of an image sensor, wherein the dual conversion gain pixel is operable to sequentially output a reset pixel value and a signal pixel value sequentially with both a first gain and a second gain different to the first gain, the method comprising:
- storing, in analogue storage, the reset pixel value output with the first gain;
- sequentially receiving, at a converter stage, the reset pixel value output with the second gain as a first analogue input and the signal pixel value output with the second gain as a second analogue input;
- sequentially sampling, at the converter stage, the first and second inputs and outputting a first digital value indicative of a difference between the reset pixel value output with the second gain and the signal pixel value output with the second gain;
- receiving, at the converter stage, the reset pixel value output with the first gain and stored in the analogue storage as a first input and the signal pixel value output with the first gain as a second input;
- and
- sampling, at the converter stage, the first and second inputs and outputting a differential signal indicative of a difference between the reset pixel value output with the first gain and the signal pixel value output with the first gain.
Dependencies are inferred from the claim text.