Abstract: An image sensor pixel may include a photodiode, a charge storage region, a floating diffusion node, and a capacitor. A first transistor may be coupled between the photodiode and the charge storage region. A second transistor may be coupled between the charge storage region and the capacitor. The photodiode may generate image signals corresponding to incident light. Multiple image signals may be summed at the charge storage region. The second transistor may determine a portion of the image signal that may be sent to the capacitor for storage. The portion of the image signal that is sent to the capacitor may be a low gain signal. A remaining portion of the image signal may be a high gain signal. The image sensor pixel may also include readout circuitry that is configured to readout low and high gain signals stored at the floating diffusion node in a double-sampling readout operation.

Abstract: An image sensor may have an array of pixels that include nested sub-pixels that each have at least one respective photodiode. An inner sub-pixel of a pixel with nested sub-pixels may have a relatively lower effective light collecting area compared to an outer sub-pixel of the pixel within which the inner sub-pixel is nested. A pixel circuit for the nested sub-pixels may include an overflow capacitor and/or a coupled gate circuit used to route charges from the photodiode in the inner sub-pixel. The lower light collecting area of the photodiode in the inner sub-pixel, with optional flicker mitigation charge routing from the coupled gates structure, may reduce the size of the capacitors required to capture photodiode and photodiode overflow charge responses. Flicker mitigation charge routing using a coupled gates structure may allow an adjustable proportion of the overflow charge to be stored in one or more storage capacitors.

Abstract: An image sensor pixel may include a photodiode, a charge storage region, a floating diffusion node, and a capacitor. A first transistor may be coupled between the photodiode and the charge storage region. A second transistor may be coupled between the charge storage region and the capacitor. The photodiode may generate image signals corresponding to incident light. Multiple image signals may be summed at the charge storage region. The second transistor may determine a portion of the image signal that may be sent to the capacitor for storage. The portion of the image signal that is sent to the capacitor may be a low gain signal. A remaining portion of the image signal may be a high gain signal. The image sensor pixel may also include readout circuitry that is configured to readout low and high gain signals stored at the floating diffusion node in a double-sampling readout operation.

Abstract: An image sensor pixel may include a photodiode, a charge storage region, a floating diffusion node, and a capacitor. A first transistor may be coupled between the photodiode and the charge storage region. A second transistor may be coupled between the charge storage region and the capacitor. The photodiode may generate image signals corresponding to incident light. Multiple image signals may be summed at the charge storage region. The second transistor may determine a portion of the image signal that may be sent to the capacitor for storage. The portion of the image signal that is sent to the capacitor may be a low gain signal. A remaining portion of the image signal may be a high gain signal. The image sensor pixel may also include readout circuitry that is configured to readout low and high gain signals stored at the floating diffusion node in a double-sampling readout operation.

Abstract: An image sensor may include one or more pixels having a coupled gate structure that may selectively route overflow charge from a photodiode to increase the dynamic range of the pixel. The coupled gate structure may include two, three or four transistors. During charge accumulation in the pixel, overflow charge may pass from a photodiode to the coupled gate structure to be selectively routed to one of a plurality of paths. Timing of control signals for a subset of the transistors in the coupled gate structure may alternate such that only one transistor is active to pass charge to one of the plurality of paths at any given time. Depending on the selected path, overflow charge may be routed to a pixel voltage supply or to one or more storage nodes in the pixel. Pixels may also include a dual-gain structure, which may provide additional charge storage capacity.

Abstract: The image sensor pixel may include a photodiode, a charge storage region, readout circuitry, and a transfer transistor that couples the photodiode to the charge storage region. The photodiode may generate first and second image signals during first and second exposure periods, respectively. The transfer transistor may transfer the first image signal to the charge storage region. While generating the second image signal, the readout circuitry may perform readout operations on the first image signal. Thereafter, the charge storage region may be reset to a reset voltage level. The readout circuitry may perform readout operations on the reset voltage level. Then, transfer transistor may transfer the second image signal to the charge storage region. The readout circuitry may perform readout operations on the second image signal. The readout operations on both the first and second image signals may be double sampling readouts.

Abstract: An image sensor pixel may include a photodiode, a charge storage region, a floating diffusion node, and a capacitor. A first transistor may be coupled between the photodiode and the charge storage region. A second transistor may be coupled between the charge storage region and the capacitor. The photodiode may generate image signals corresponding to incident light. Multiple image signals may be summed at the charge storage region. The second transistor may determine a portion of the image signal that may be sent to the capacitor for storage. The portion of the image signal that is sent to the capacitor may be a low gain signal. A remaining portion of the image signal may be a high gain signal. The image sensor pixel may also include readout circuitry that is configured to readout low and high gain signals stored at the floating diffusion node in a double-sampling readout operation.

Abstract: An image sensor may have an array of pixels that include nested sub-pixels that each have at least one respective photodiode. An inner sub-pixel of a pixel with nested sub-pixels may have a relatively lower effective light collecting area compared to an outer sub-pixel of the pixel within which the inner sub-pixel is nested. A pixel circuit for the nested sub-pixels may include an overflow capacitor and/or a coupled gate circuit used to route charges from the photodiode in the inner sub-pixel. The lower light collecting area of the photodiode in the inner sub-pixel, with optional flicker mitigation charge routing from the coupled gates structure, may reduce the size of the capacitors required to capture photodiode and photodiode overflow charge responses. Flicker mitigation charge routing using a coupled gates structure may allow an adjustable proportion of the overflow charge to be stored in one or more storage capacitors.

Abstract: An image sensor may include one or more pixels having a coupled gate structure that may selectively route overflow charge from a photodiode to increase the dynamic range of the pixel. The coupled gate structure may include two, three or four transistors. During charge accumulation in the pixel, overflow charge may pass from a photodiode to the coupled gate structure to be selectively routed to one of a plurality of paths. Timing of control signals for a subset of the transistors in the coupled gate structure may alternate such that only one transistor is active to pass charge to one of the plurality of paths at any given time. Depending on the selected path, overflow charge may be routed to a pixel voltage supply or to one or more storage nodes in the pixel. Pixels may also include a dual-gain structure, which may provide additional charge storage capacity.

Abstract: In accordance with an embodiment, a 4T pixel includes a first switch having a control terminal and first and second current carrying terminals and an amplifier having an input terminal and an output terminal. A second switch is coupled between the first switch and the amplifier.

Abstract: Systems and methods of pixel sensing circuits. In accordance with a first embodiment of the present invention, a pixel sensing circuit includes a floating diffusion functionally coupled to and surrounded by a ring transfer transistor. The ring transfer transistor is functionally coupled to and surrounded by a photo diode. The photo diode may be surrounded by a region of poly silicon. The disclosed structure provides radiation hardening and low light performance.

Abstract: A method and apparatus for white balance correction using illuminant estimation includes calculating a weighted average of the color coordinates of points in a color image to determine an estimated illuminant of the color image in the color space of an image sensor and selecting white balance correction factors for the color image using the estimated illuminant of the color image and color coordinates of one or more of a number of reference illuminant points in the color space of the image sensor.

Abstract: Systems and methods of pixel sensing circuits. In accordance with a first embodiment of the present invention, a pixel sensing circuit includes a floating diffusion functionally coupled to and surrounded by a ring transfer gate. The ring transfer gate is functionally coupled to and surrounded by a photo diode. The photo diode may be surrounded by a region of poly silicon. The disclosed structure provides radiation hardening and low light performance.

Abstract: Systems and methods of pixel sensing circuits. In accordance with a first embodiment of the present invention, a pixel sensing circuit includes a floating diffusion functionally coupled to and surrounded by a ring transfer gate. The ring transfer gate is functionally coupled to and surrounded by a photo diode. The photo diode may be surrounded by a region of poly silicon. The disclosed structure provides radiation hardening and low light performance.

Abstract: A method and apparatus for white balance correction using illuminant estimation includes calculating a weighted average of the color coordinates of points in a color image to determine an estimated illuminant of the color image in the color space of an image sensor and selecting white balance correction factors for the color image using the estimated illuminant of the color image and color coordinates of one or more of a number of reference illuminant points in the color space of the image sensor.

Abstract: A method and apparatus for reconstructing a full color image. The method may include receiving a signal pertaining to an encoded image, and reconstructing four color values for each pixel location in the image using a set of convolution masks.

Abstract: A charge pump circuit and method for supplying power. The charge pump circuit includes a first circuit receiving at least one low voltage signal and generating an output voltage signal. The charge pump circuit also includes a second circuit receiving a clock signal and the output voltage signal. The second circuit sends a request signal based on a comparison of the output voltage signal with two reference voltage signals, where the two reference voltage signals are derived from two supply voltage signals having a substantially constant potential difference. The charge pump circuit further includes a high voltage generator receiving the request signal and sending the two supply voltage signals to the first circuit and the second circuit. The high voltage generator adjusts the voltage potentials of the two supply voltage signals such that the voltage potential of the output voltage signal falls between the voltage potentials of the two reference voltage signals.

Abstract: A charge pump circuit and method for supplying power. The charge pump circuit includes a first circuit receiving at least one low voltage signal and generating an output voltage signal. The charge pump circuit also includes a second circuit receiving a clock signal and the output voltage signal. The second circuit sends a request signal based on a comparison of the output voltage signal with two reference voltage signals, where the two reference voltage signals are derived from two supply voltage signals having a substantially constant potential difference. The charge pump circuit further includes a high voltage generator receiving the request signal and sending the two supply voltage signals to the first circuit and the second circuit. The high voltage generator adjusts the voltage potentials of the two supply voltage signals such that the voltage potential of the output voltage signal falls between the voltage potentials of the two reference voltage signals.