Method and system to differentially enhance sensor dynamic range
First Claim
1. A method to increase effective differential dynamic range for a differential pixel detector exposed to optical energy having a common mode component, the differential pixel detector including a first photodetector and an associated first capacitor, and a second photodetector and an associated second capacitor, the method comprising:
- (a) at start of an integration time T, resetting voltage on each said capacitor to a fixed reference voltage;
(b) during said integration time T, directly integrating photocurrent generated by said first photodetector in said first capacitor, and directly integrating photocurrent generated by said second photodetector in said second capacitor;
(c) within said integration time T, before voltage developed across either said first capacitor or said second capacitor attains a saturation voltage Vsat associated with said differential pixel detector resetting the developed voltage on said capacitor such that a desired differential pixel detector signal is still determinable.
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Abstract
Effective differential dynamic range in a differential pixel detector is increased by avoiding saturation effects due to common mode contribution in optical energy to be detected. Photocurrent generated by each photodetector pair is directly integrated by an associated capacitor over an integration time T. Within time T, before either integrated capacitor voltage reaches Vsat for the photodetector, at least one of the capacitors is reset to a voltage such that the desired differential detector signal is still determinable. Reset may be generated externally or internally to the differential pixel detector.
235 Citations
27 Claims
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1. A method to increase effective differential dynamic range for a differential pixel detector exposed to optical energy having a common mode component, the differential pixel detector including a first photodetector and an associated first capacitor, and a second photodetector and an associated second capacitor, the method comprising:
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(a) at start of an integration time T, resetting voltage on each said capacitor to a fixed reference voltage;
(b) during said integration time T, directly integrating photocurrent generated by said first photodetector in said first capacitor, and directly integrating photocurrent generated by said second photodetector in said second capacitor;
(c) within said integration time T, before voltage developed across either said first capacitor or said second capacitor attains a saturation voltage Vsat associated with said differential pixel detector resetting the developed voltage on said capacitor such that a desired differential pixel detector signal is still determinable. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A differential pixel detector responsive to optical energy having a common mode component, comprising:
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a first photodetector and an associated first capacitor that directly integrates photocurrent generated by said first photodetector during an integration time T;
a second photodetector and an associated second capacitor that directly integrates photocurrent generated by said second photodetector during said integration time T;
means for forcing potential on each said capacitor to a fixed voltage potential before start of said integration time T; and
means for resetting potential on either capacitor during said integration time T before said potential attains a saturation voltage Vsat associated with said differential pixel detector such that a desired differential pixel detector signal is still determinable. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification