Abstract: An A/D converter suitable for use in a system in which the signal power of noise increases with the signal power of the signal, such as an imaging system, utilizes a variable quantization system for converting analog signals into digital signals. The variable quantization is controlled so that low signal levels the quantization is similar or identical to conventional A/D converters, while the quantization level is increased at higher signal levels. Thus, higher resolution is provided at low signal levels while lower resolution is produced at high signal levels.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: A signal chain for an image sensor is disclosed. The signal chain includes photo sensing elements, pixel readout circuits, and an amplifier. Each pixel readout circuit receives a charge-induced signal and a reset signal from one of the photo sensing elements. The readout circuit computes a difference signal between the charge-induced signal and said reset signal. The difference signal is measured with respect to a reference signal. The amplifier is coupled to the pixel readout circuits, and configured to supply the reference signal during computation of the difference signal. Further, the amplifier amplifies the difference signal when the computation is done.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: Techniques are disclosed for enhancing the speed at which pixel levels are read out and sampled for processing. A method of processing pixel levels includes clamping a pixel readout line to a voltage level less than a voltage corresponding to a signal sensed by an n-MOS pixel. Subsequently, the pixel readout line is coupled to an output of an n-MOS source-follower and the pixel signal is read out onto the pixel readout line through the n-MOS source-follower. The pixel signal that was read out is passed through a p-MOS source-follower to a processing circuit. Before passing the pixel signal through the p-MOS source-follower to the processing circuit, a capacitive storage node in the processing circuit is clamped to a voltage greater than a signal at an input to the p-MOS source-follower. Subsequently, an output of the p-MOS source-follower is coupled to the processing circuit, and a signal corresponding to the pixel signal is stored by the processing circuit.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: An apparatus has a pixel that includes (i) a buffer transistor having an input, (ii) first and second capacitive storage elements each of which selectively can be coupled to the input of the buffer transistor, and (iii) a photosensitive element having an output which selectively can be coupled to the input of the buffer transistor. A readout circuit selectively can be coupled to an output of the buffer transistor. A first signal level, sensed by the photosensitive element, can be stored by the first capacitive storage element, and a second signal level, sensed by the photosensitive element, can be stored by the second capacitive storage element. The first and second signal levels can be read out from the pixel.

Abstract: Automatic exposure adjusting device considers the image on a pixel-by-pixel basis. Each pixel is characterized according to its most significant bits. After the pixels are characterized, the number of pixels in any particular group is counted. That counting is compared with thresholds which set whether the image is over exposed, under exposed, and can optionally also determine if the image is seriously over exposed or seriously under exposed. Adjustment of the exposure is carried out to bring the image to a more desired state.

Abstract: Techniques are disclosed for enhancing the speed at which pixel levels are read out and sampled for processing. A method of processing pixel levels includes clamping a pixel readout line to a voltage level less than a voltage corresponding to a signal sensed by an n-MOS pixel. Subsequently, the pixel readout line is coupled to an output of an n-MOS source-follower and the pixel signal is read out onto the pixel readout line through the n-MOS source-follower. The pixel signal that was read out is passed through a p-MOS source-follower to a processing circuit. Before passing the pixel signal through the p-MOS source-follower to the processing circuit, a capacitive storage node in the processing circuit is clamped to a voltage greater than a signal at an input to the p-MOS source-follower. Subsequently, an output of the p-MOS source-follower is coupled to the processing circuit, and a signal corresponding to the pixel signal is stored by the processing circuit.

Abstract: A shutter system for a pixel array is disclosed. The system includes a read shift register, first and second reset shift registers, and a plurality of logic gates. The read shift register is configured to sequentially count rows of the pixel array from top to bottom, such that the read shift register generates a read pointer. The first reset shift register is configured to sequentially reset rows of the pixel array from top to bottom. The first reset shift register provides a first reset pointer for allowing reset of pixels in a row indicated by the first reset pointer. The first reset pointer allows reset of pixels prior to reading of the pixels in a row indicated by the read pointer. The time difference between the first reset pointer and the read pointer indicates an exposure time.

Abstract: A signal chain for an image sensor is disclosed. The signal chain includes photo sensing elements, pixel readout circuits, and an amplifier. Each pixel readout circuit receives a charge-induced signal and a reset signal from one of the photo sensing elements. The readout circuit computes a difference signal between the charge-induced signal and said reset signal. The difference signal is measured with respect to a reference signal. The amplifier is coupled to the pixel readout circuits, and configured to supply the reference signal during computation of the difference signal. Further, the amplifier amplifies the difference signal when the computation is done.

Abstract: A signal chain for an image sensor is disclosed. The signal chain includes photo sensing elements, pixel readout circuits, and an amplifier. Each pixel readout circuit receives a charge-induced signal and a reset signal from one of the photo sensing elements. The readout circuit computes a difference signal between the charge-induced signal and said reset signal. The difference signal is measured with respect to a reference signal. The amplifier is coupled to the pixel readout circuits, and configured to supply the reference signal during computation of the difference signal. Further, the amplifier amplifies the difference signal when the computation is done.

Abstract: A CMOS imager includes an array of active pixel sensors, wherein each pixel is associated with a respective column in the array. The imager also includes multiple circuits for reading out values of pixels from the active sensor array. Each readout circuit can be associated with a respective pair of columns in the array and can include first and second sample-and-hold circuits. The first and second sample-and-hold circuits are associated, respectively, with first and second columns of pixels in the array. Each readout circuit also includes an operational amplifier-based charge sensing circuit that selectively provides an amplified differential output signal based on signals sampled either by the first sample-and-hold circuit or the second sample-and-hold circuit. The readout circuit also has an analog-to-digital converter for converting the differential output to a corresponding digital signal using a successive approximation technique.

Abstract: Wide dynamic range operation is used to write a signal in a freeze-frame pixel into the memory twice, first after short integration and then after long integration. The wide dynamic range operation allows the intra-scene dynamic range of images to be extended by combining the image taken with a short exposure time with the image taken with a long exposure time. A freeze-frame pixel is based on voltage sharing between the photodetector PD and the analog memory. Thus, with wide dynamic range operation, the resulting voltage in the memory may be a linear superposition of the two signals representing a bright and a dark image after two operations of sampling.

Abstract: Wide dynamic range operation is used to write a signal in a freeze-frame pixel into the memory twice, first after short integration and then after long integration. The wide dynamic range operation allows the intra-scene dynamic range of images to be extended by combining the image taken with a short exposure time with the image taken with a long exposure time. A freeze-frame pixel is based on voltage sharing between the photodetector PD and the analog memory. Thus, with wide dynamic range operation, the resulting voltage in the memory may be a linear superposition of the two signals representing a bright and a dark image after two operations of sampling.

Abstract: A lock in pinned photodiode photodetector includes a plurality of output ports which are sequentially enabled. Each time when the output port is enabled is considered to be a different bin of time. A specified pattern is sent, and the output bins are investigated to look for that pattern. The time when the pattern is received indicates the time of flight. A CMOS active pixel image sensor includes a plurality of pinned photodiode photodetectors that use a common output transistor. In one configuration, the charge from two or more pinned photodiodes may be binned together and applied to the gate of an output transistor.

Abstract: A lock in pinned photodiode photodetector includes a plurality of output ports which are sequentially enabled. Each time when the output port is enabled is considered to be a different bin of time. A specified pattern is sent, and the output bins are investigated to look for that pattern. The time when the pattern is received indicates the time of flight A CMOS active pixel image sensor includes a plurality of pinned photodiode photodetectors that use a common output transistor. In one configuration, the charge from two or more pinned photodiodes may be binned together and applied to the gate of an output transistor.

Abstract: A method of operating a CMOS imager is presented wherein a reset transistor source/drain of a first pixel is biased with a first voltage source, a source follower transistor of a second pixel is biased with the same first voltage source, a reset transistor source/drain of the second pixel is biased with a second voltage source, and the first voltage source is dropped to ground during a reset of the second pixel.