Amplification with feedback capacitance for photodetector signals
First Claim
1. A pixel circuit comprising:
- a photodetector that generates charge;
a storage node for receiving charge generated by said photodetector;
an amplifier having an input coupled to said storage node and an output that provides an amplified input signal, said amplifier having a first power mode during a first operational period and a second power mode during a second operational period;
a feedback capacitor, said capacitor providing feedback between the amplifier'"'"'s output and input; and
a reset switch that resets said storage node and said amplifier when closed.
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Accused Products
Abstract
Signals from an imager pixel photodetector are received by an amplifier having capacitive feedback, such as a capacitive transimpedance amplifier (CTIA). The amplifier can be operated at a low or no power level during an integration period of a photodetector to reduce power dissipation. The amplifier can be distributed, with an amplifier element within each pixel of an array and with amplifier output circuitry outside the pixel array. The amplifier can be a single ended cascode amplifier, a folded cascode amplifier, a differential input telescopic cascode amplifier, or other configuration. The amplifier can be used in pixel configurations where the amplifier is directly connected to the photodetector, or in configurations which use a transfer transistor to couple signal charges to a floating diffusion node with the amplifier being coupled to the floating diffusion node.
29 Citations
46 Claims
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1. A pixel circuit comprising:
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a photodetector that generates charge; a storage node for receiving charge generated by said photodetector; an amplifier having an input coupled to said storage node and an output that provides an amplified input signal, said amplifier having a first power mode during a first operational period and a second power mode during a second operational period; a feedback capacitor, said capacitor providing feedback between the amplifier'"'"'s output and input; and a reset switch that resets said storage node and said amplifier when closed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An integrated circuit comprising:
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a pixel array with rows and columns of pixel cells, and, for each column, a column readout line that connects to the column'"'"'s pixel cells;
each pixel cell including;a photodetector that provides a first signal indicating detected light; an amplifier with an input that receives the first signal and an output that provides an output signal based on the first signal, said amplifier having a first power mode during an integration period and a second power mode during a readout period; feedback capacitance that provides feedback from the amplifier output to the amplifier input; and means for resetting said amplifier and said capacitance; and readout circuitry connected to the column readout line, the readout circuitry providing readout signals from the column pixel cells;
the readout circuitry including sampling circuitry for sampling the amplifier output signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. An integrated circuit comprising:
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a pixel array with rows and columns of pixel cells and, for each column, a column readout line that connects to pixel cells of a column;
each pixel cell including;a photodetector that provides a first signal indicating detected light; an amplifier with an input that receives the first signal and an output that provides signals based on the first signal, said amplifier having a first power mode during a first operational period and a second power mode during a second operational period; and feedback capacitance that provides feedback from the amplifier output to the amplifier input; and readout circuitry connected to the column readout line, the readout circuitry providing readout signals from a column line;
the readout circuitry including;amplifier output stage circuitry arranged such that when the pixel cell is connected to a column line the amplifier and the output stage circuitry form a distributed amplifier, wherein each pixel further includes a reset switch that, when closed, resets the amplifier and a floating diffusion node coupled to the photodetector and to the input of said amplifier. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. An imaging circuit comprising:
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an array of pixels, each pixel including; a photodetector that generates charge in response to light; a storage node for storing charges generated by said photodetector; an amplifier that amplifies a signal received from said storage node, said amplifier having a first power mode during a first operational period and a second power mode during a second operational period; a feedback capacitor that provides feedback to an input of the amplifier; and a reset switch that resets said storage node when closed, wherein an output circuit of said amplifier is located outside said array of pixels and said amplifier is a capacitive transimpedance amplifier. - View Dependent Claims (34, 35, 36, 37)
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38. A pixel sensor array comprising:
an array of pixel cells, each pixel cell including; a photodetector that generates charge in response to light; an amplifier that amplifies a signal received from said photodetector, said amplifier having a first power mode during an integration period and a second power mode during a readout period; a feedback capacitor that provides feedback to the input of the amplifier; and a reset switch that resets said capacitor and amplifier when closed. - View Dependent Claims (39)
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40. An imaging system comprising:
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a processor; an imaging device coupled to said processor, the imaging device comprising; an array of pixels, each pixel including; a photodetector that generates charge in response to light; a storage node for storing charges generated by said photodetector; an amplifier that amplifies charges on said storage node, said amplifier having a first power mode during an integration period and a second power mode during a readout period; a feedback capacitor that provides feedback to an input of the amplifier; and a reset switch that resets the storage node when closed; and amplifier output circuitry located outside the pixel array;
the amplifier, the amplifier output circuitry, and the feedback capacitor together forming a capacitive transimpedance amplifier. - View Dependent Claims (41, 42, 43, 44, 45, 46)
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Specification