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US 2018/0324378 A1Published application
Comparator for double ramp analog to digital converter
AssigneeOmniVision Technologies, Inc.
InventorsHiroaki Ebihara, Zheng Yang
Life of this patent
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Abstract
Apparatuses and method for an image sensor with increased analog to digital conversion range and reduced noise are described herein. An example method may include disabling a first auto-zero switch of a comparator, the first auto-zero switch coupled to auto-zero a reference voltage input of the comparator, adjusting an auto-zero offset voltage of a ramp voltage provided to the reference voltage input of the comparator, and disabling a second auto-zero switch of the comparator, the second auto-zero switch coupled to auto-zero a bitline input of the comparator.
Claims6
A method, comprising:
- disabling a first auto-zero switch of a comparator, the first auto-zero switch coupled to auto-zero a reference voltage input of the comparator;
- adjusting an auto-zero offset voltage of a ramp voltage provided to the reference voltage input of the comparator;
- and
- disabling a second auto-zero switch of the comparator, the second auto-zero switch coupled to auto-zero a bitline input of the comparator,
- wherein the first auto-zero switch is coupled between a gate of the reference voltage input and a node between the reference voltage input and a cascode device, wherein the reference voltage input is an NMOS transistor, and wherein the cascode device is coupled between the reference voltage input and a PMOS transistor,
- wherein the second auto-zero switch is coupled between a gate of the bitline input and a node between bitline input and a cascode device, wherein the bitline input is an NMOS transistor, and wherein the cascode device is coupled between the bitline input and a PMOS transistor.
3 more elements
Dependencies are inferred from the claim text.