Method for obtaining a high dynamic range read-out signal of a CMOS-based pixel structure and such CMOS-based pixel structure
DCFirst Claim
1. A method for obtaining a read-out signal of a MOS-based pixel structure having in a MOS technology at least a photosensitive element with an output node and a memory element with a first switch therebetween, the method comprising the steps of while acquiring charge carriers on said output node of said photosensitive element, said charge carriers being converted from radiation impinging on the photosensitive element:
- after a first time period opening said first switch thereby storing a first number of charge carriers on said memory element and creating a first signal;
after a second time period, creating a second signal from a second number of said charge carriers being stored on said output node of said photosensitive element, andcombining at least said first and said second signals in order to obtain said read-out signal.
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Abstract
A method is disclosed for obtaining a read-out signal of a MOS-based pixel structure having at least a photosensitive element with an output node and a memory element with a first switch therebetween. The method comprises the steps of while acquiring charge carriers on said output node of said photosensitive element, said charge carriers being converted from electromagnetic radiation on the photosensitive element, after a first time period creating a first signal, and after a second time period, creating a second signal, said read-out signal being a combination of at least said first and said second signals.
According to the present invention, there is no limitation to the amount of collected charges in none of the integrated periods. The signal collected during the first period is memorized by a switch which shortly opens and closes between the period. The switch is thus in the same state in both period of time. After a second period, there are thus two charge packets, each obtained during a different time. In order to read-out, these two charge packets are then combined into one reading. This combination is known either by adding or subtracting this charge packets, e.g., by adding or subtracting them in the circuitry external to the sensor.
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Citations
36 Claims
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1. A method for obtaining a read-out signal of a MOS-based pixel structure having in a MOS technology at least a photosensitive element with an output node and a memory element with a first switch therebetween, the method comprising the steps of while acquiring charge carriers on said output node of said photosensitive element, said charge carriers being converted from radiation impinging on the photosensitive element:
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after a first time period opening said first switch thereby storing a first number of charge carriers on said memory element and creating a first signal; after a second time period, creating a second signal from a second number of said charge carriers being stored on said output node of said photosensitive element, and combining at least said first and said second signals in order to obtain said read-out signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A MOS-based pixel structure, comprising at least:
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a photosensitive element for converting radiation into charge carriers, and being connected to a voltage with a reset switch; a memory element being connected to an amplifier; and a first switch in-between said photosensitive element and said memory element, said first switch being opened causing a first number of said charge carriers being stored on said memory element. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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Specification