Image sensor device capable of improving signal discrimination in dark condition and avoiding signal saturation in bright condition
AssigneePixart Imaging Inc.
InventorsKuan Tang, Jui-Te Chiu
Life of this patent
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Abstract
An image sensor device is provided to effectively improve the signal discrimination of sensed/sampled pixel values/signals in the image sensor device operating in a dark condition as well as effectively avoiding signal saturation when such image sensor device operates in a light/bright condition. Such image sensor device, when operating in dark/light conditions, can perform the exposure operation to get/sample accurate pixel image signal and pixel reset signal for only one time without estimating the pixel image signal and pixel reset signal by performing the exposure operation twice.
Claims20
An image sensor device, comprising:
- a plurality of pixel units, each pixel unit comprising:
- a photodiode, having a first end coupled to a ground level and a second end;
- a transfer gate transistor, having a first terminal coupled to the photodiode, a second terminal coupled to a first floating diffusion node, and a control terminal coupled to a transfer gate signal;
- a first source follower transistor, having a first terminal coupled to the first supply voltage level, a second terminal coupled to an output node, and a control terminal coupled to the first floating diffusion node;
- a reset transistor, having a first terminal coupled to a second supply voltage level, a second terminal coupled to a second floating diffusion node, and a control terminal coupled to a reset signal;
- a reset control transistor, having a first terminal coupled to the second floating diffusion node, a second terminal coupled to the first floating diffusion node, and a control terminal coupled to a reset control signal;
- and
- a second source follower transistor, having a first terminal coupled to the first supply voltage level, a second terminal coupled to the output node, and a control terminal coupled to the second floating diffusion node;
- wherein a potential barrier caused by the reset control transistor, which is controlled by the reset control signal, is lower than a potential barrier caused by the transfer gate transistor when being turned off.
Dependencies are inferred from the claim text.