Abstract: The active pixel includes a photodiode, a transfer gate, and a reset transistor. The photodiode is substantially covered with an overlying structure, thus protecting the entire surface of the photodiode from damage. This substantially eliminates potential leakage current sources, which result in dark current. In one embodiment, the photodiode is covered by a FOX region in combination with the transfer gate.

Abstract: A system and method for applying a layer of material in the image sensor fabrication process in order to increase the absorption of specific range light spectrum by the image sensor is described. The mechanism adopted is by converting light rays from higher energy range (shorter wavelength) to lower energy range (longer wavelength) such that the light absorption by the image sensor can be increased.

Abstract: A CMOS image sensor that has reduced transistor count is disclosed. The individual pixels are formed by a photodiode and a transfer transistor. An output node receives the signal from the photodiode via the transfer transistor. The output node is shared between multiple pixels. Further, a reset transistor is coupled between a selectable low voltage rail Vss or a high voltage reference Vref and the output node. The gate of an output transistor is then coupled to the output node. Both the reset transistor and output transistors are shared between multiple pixels. Further, the pixels have a mirror symmetry about the output transistor or output node.

Abstract: The active pixel includes a photodiode, a reset transistor, and a pixel output transistor. The photodiode is substantially covered with a protective structure, thus protecting the entire surface of the photodiode from damage. This substantially eliminates potential leakage current sources, which result in dark current. The protective structure has a photodiode contact formed therein to electrically connect the photodiode to the pixel output transistor.

Abstract: Mechanical shutter devices for image sensors and associated methods are disclosed. In one aspect of the invention, an imaging system includes an image sensor having an array of pixels with photosensitive elements. The imaging system can further include a signal processing device coupled to the image sensor to receive signals from the image sensor. The system can still further include a shutter device having an open and a closed position. The shutter device can be located proximate to the photosensitive elements of the pixels so that when the shutter device is in the open position, light is allowed to reach the photosensitive elements of the pixels, and when the shutter device is in the closed position, all substantial amounts of light are prevented from reaching the photosensitive elements of the pixels. The image sensor can be configured to store the signals until the signal processing device can receive the signals.

Abstract: A method for protecting an image sensor die is disclosed. The method comprises forming a plurality of image sensor die having micro-lenses onto a semiconductor wafer. Then, a protective layer is formed over the image sensor die. After the protective layer has been formed, and without any removal step of the protective layer, the wafer is diced to separate the plurality of image sensor die. Finally, the image sensor die are mounted onto an integrated circuit package and the protective layer is removed.

Abstract: A CMOS image sensor that has reduced transistor count is disclosed. The individual pixels are formed by a pinned photodiode and a transfer transistor. An output node receives the signal from the photodiode via the transfer transistor. The output node is shared between multiple pixels. Further, a reset transistor is coupled between a selectable low voltage rail Vss or a high voltage reference Vref and the output node. The gate of an output transistor is then coupled to the output node. Both the reset transistor and output transistors are shared between multiple pixels.

Abstract: A pixel and image sensor formed in accordance with the present invention has two modes of operation: a high illumination mode and a low illumination mode. The present invention switches on an auxiliary capacitance at the floating node based upon the amount of illumination on the image sensor. The amount of illumination on the image sensor can be determined in a variety of ways. Once the level of illumination is determined, a decision is made by comparing the level of illumination to a threshold whether to switch on the auxiliary capacitance (for high illumination) or not switch on the auxiliary capacitance (for low illumination).

Abstract: In a CMOS image sensor, it is important to control the exposure time or gain. For varying changes in ambient light, the exposure time of the array must be changed. The present invention describes a method for controlling the exposure time or gain to ensure a smooth and fast change in the brightness of the obtained image. If the exposure time is the be decremented or incremented, then the gain control is increased or decreased, respectively to smooth out the changes in image brightness. This substantially reduces image flicker.

Abstract: A method of reading out a pixel signal from a pixel is disclosed. The method comprises first capturing a first black reference signal from the pixel prior to the pixel starting an integration period. Next, after completion of the integration period, a pixel signal is captured. Next, a second black reference signal is captured following completion of the integration period. Finally, the first black reference signal, second black reference signal, and pixel signal is output.

Abstract: A method and apparatus for a digital shutter is provided. In one embodiment, the invention is an apparatus. The apparatus includes an array of digital image sensor elements. The apparatus also includes a digital shutter coupled to the array of digital image sensor elements. In an alternate embodiment, the invention is a method. The method includes exposing an array of digital image sensors to an incoming image. The method further includes transforming a digital shutter to a non-transmissive state. The digital shutter is interposed between the array of digital image sensors and a source of the incoming image. In yet another embodiment, the invention is an apparatus. The apparatus includes means for sensing an incoming image. The apparatus also includes means for digitally blocking light from a source of the incoming image.

Abstract: An active pixel for an image sensor that has minimized 1/f noise. The active pixel includes an amplification transistor that is implemented as a “body current” transistor. This minimizes the effect of surface oxide traps that are believed to cause 1/f noise. Further, the reset transistor, the row select transistor, and transfer transistor of the active pixel may also be implemented as a body current transistor to further reduce 1/f noise.

Abstract: An active pixel for an image sensor that has minimized 1/f noise. The active pixel includes an amplification transistor that is implemented as a “body current” transistor. This minimizes the effect of surface oxide traps that are believed to cause 1/f noise. Further, the reset transistor, the row select transistor, and transfer transistor of the active pixel may also be implemented as a body current transistor to further reduce 1/f noise.

Abstract: The image sensor includes a first group and a second group of column readout circuits for reading out pixel signals from said pixels. The total number of column readout circuits in each group is substantially less than the number of columns in the image sensor pixel array. Further included is a multiplexer bus system having selection switches for selectively switching pixel signals from a block of pixels in a column as input into the first group of column readout circuits. The multiplexer bus system also selectively switches pixel signals from another block of pixels in a column as input into a second group of column readout circuits. However, when the first group of column readout circuits is reading and storing said pixel signals, the second group of column readout circuits is transferring out the processed signals. Thus, the first and second groups work alternately.

Abstract: A CMOS camera image sensor that may be combined with additional CMOS camera image sensors to form a multiple-camera security monitoring system. Each CMOS image sensor includes phase-locked loop circuitry. The phase-locked loop circuitry receives a reference input signal and in response thereto synchronizes the video output of the CMOS image sensor to the reference input signal. In one configuration, one of the CMOS image sensors provides the reference signal, while in another configuration, the reference input signal may come from an external circuit. Each CMOS image sensor also includes state selection circuitry. The state selection circuitry allows the video output from the CMOS image sensor to be displayed on ¼, ½, or all of a display. Thus, the video signals from multiple CMOS image sensors may be displayed on a video monitor simultaneously.

Abstract: A CMOS image sensor that has reduced transistor count is disclosed. The individual pixels are formed by a pinned photodiode and a transfer transistor. An output node receives the signal from the photodiode via the transfer transistor. The output node is shared between multiple pixels. Further, a reset transistor is coupled between a selectable low voltage rail Vss or a high voltage reference Vref and the output node. The gate of an output transistor is then coupled to the output node. Both the reset transistor and output transistors are shared between multiple pixels.

Abstract: A method for reducing dark current in a photodiode is disclosed. The photodiode comprises a N-well formed in a P-substrate. The method comprises doping the surface of said N-well with a nitrogen dopant. Alternatively, an oxygen or silicon dopant may be used. Still alternatively, a silicon oxynitride layer may be formed over the N-well.

Abstract: A method for protecting an image sensor die is disclosed. The method comprises forming a plurality of image sensor die having micro-lenses onto a semiconductor wafer. Then, a protective layer is formed over the image sensor die. After the protective layer has been formed, and without any removal step of the protective layer, the wafer is diced to separate the plurality of image sensor die. Finally, the image sensor die are mounted onto an integrated circuit package and the protective layer is removed.

Abstract: The active pixel includes a photodiode, a reset transistor, and a pixel output transistor. The photodiode is substantially covered with a protective structure, thus protecting the entire surface of the photodiode from damage. This substantially eliminates potential leakage current sources, which result in dark current. The protective structure has a photodiode contact formed therein to electrically connect the photodiode to the pixel output transistor.

Abstract: In a CMOS image sensor, it is important to control the exposure time or gain. For varying changes in ambient light, the exposure time of the array must be changed. The present invention describes a method for controlling the exposure time or gain. Each of the intensities of the pixels in a frame is analyzed to provide an indication of the number of pixels having an intensity above or below multiple predetermined thresholds. This information is then used to change the exposure time. The magnitude of change in the exposure time is also determined by the number of pixels having an intensity above or below multiple predetermined thresholds, as the case may be.