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US 2017/0374307 A1Published application
Low-power and low-mismatch correlated double sampling (cds) circuit
AssigneeQUALCOMM Incorporated
InventorsSoo Youn Kim, Alok Govil
Life of this patent
Estimating the term…
Abstract
Techniques provided herein are directed toward a simplified correlated double sampling (CDS) circuit that reduces the amount of components and potential noise sources utilized to two switches and a capacitor. Such CDS circuits can be used in conjunction with downstream programmable gain amp (PGA) circuitry to provide double sampling along with variable gain and/or other features. Embodiments may further utilize one or more analog muxes to reduce parasitic capacitance and increase accuracy.
Claims21
An apparatus for providing image sensing, the apparatus comprising:
- an active pixel sensor array comprising a pixel array having a plurality of columns of pixels;
- for each column of pixels of the plurality of columns of pixels of the active pixel sensor array, a correlated double sampling (CDS) circuit corresponding to, and coupled with, the each column of pixels, wherein each CDS circuit comprises a first switch, a first capacitor, and a second switch, wherein, for each CDS circuit:
- the first capacitor is connected in series between the first switch and the second switch without an active element disposed between the first capacitor and the second switch, and
- an input of the first switch is coupled to an output of the corresponding column of pixels;
- and
- an amplification circuit comprising a second capacitor and a third switch connected in parallel with the second capacitor, wherein, for the each CDS circuit, an output of the second switch of is coupled to an input of the amplification circuit.
3 more elements
An method of providing image sensing, the method comprising:
- obtaining, for each column of pixels in an active pixel sensor array, a first value from a pixel sensor in the column of pixels;
- storing, for each column of pixels in the active pixel sensor array, the first value with a corresponding CDS circuit comprising a first switch, a first capacitor, and a second switch, wherein:
- the first capacitor is connected in series between the first switch and the second switch without an active element disposed between the first capacitor and the second switch, and
- an input of the first switch is coupled to an output of the corresponding column of pixels;
- and
- providing, with an amplification circuit coupled to each of the CDS circuits, a plurality of output signals, wherein each output signal:
- corresponds to a column of pixels in the active pixel sensor array, and
- is based on the first value stored by the CDS circuit corresponding to the column of pixels and a second value obtained by the CDS circuit corresponding to the column of pixels;
- and
- wherein the amplification circuit comprises a second capacitor and a third switch connected in parallel with the second capacitor.
7 more elements
An apparatus comprising:
- means for obtaining, for each column of pixels in an active pixel sensor array, a first value from a pixel sensor in the each column of pixels;
- means for storing, for each column of pixels in the active pixel sensor array, the first value within a corresponding CDS circuit that does not include a buffer or amplifier;
- and
- means for providing a plurality of amplified output signals, wherein each output signal:
- corresponds to a column of pixels in the active pixel sensor array, and
- is based on the first value stored by the means for storing and a second value obtained by the means for storing corresponding to the column of pixels.
3 more elements
A non-transitory computer-readable medium comprising instructions for causing an apparatus to provide image sensing, the instructions including computer code for:
- obtaining, for each column of pixels in an active pixel sensor array, a first value from a pixel sensor in the column of pixels;
- storing, for each column of pixels in the active pixel sensor array, the first value with a corresponding CDS circuit comprising a first switch, a first capacitor, and a second switch, wherein:
- the first capacitor is connected in series between the first switch and the second switch without an active element disposed between the first capacitor and the second switch, and
- an input of the first switch is coupled to an output of the corresponding column of pixels;
- and
- providing, with an amplification circuit coupled to each of the CDS circuits, a plurality of output signals, wherein each output signal:
- corresponds to a column of pixels in the active pixel sensor array, and
- is based on the first value stored by the CDS circuit corresponding to the column of pixels and a second value obtained by the CDS circuit corresponding to the column of pixels;
- and
- wherein the amplification circuit comprises a second capacitor and a third switch connected in parallel with the second capacitor.
7 more elements
Dependencies are inferred from the claim text.