Staring IR-FPA with on-FPA adaptive dynamic range control electronics
First Claim
1. An imaging device having a plurality of electromagnetic radiation detector unit cells each of which outputs an electrical signal having a magnitude that is a function of an amount of electromagnetic radiation that is detected by the unit cell, comprising:
- a plurality of amplifier means individual ones of which have an input that is switchably coupled to individual ones of a plurality of said unit cells for receiving said electrical signals therefrom;
each of said amplifier means including,first circuit means, having inputs coupled to a source of gain correction values, for selectively setting a gain of said amplifier means for each of said plurality of unit cells that are switchably coupled to said input of said amplifier means; and
second circuit means, having inputs coupled to a source of offset correction values, for selectively setting an offset potential that said amplifier means subtracts from each of said electrical signals that are output by said plurality of unit cells that are switchably coupled to said input of said amplifier means.
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Accused Products
Abstract
An adaptive dynamic range control circuit architecture is disclosed that enables an IR-FPA (10) to achieve a higher dynamic range. The circuit architecture significantly reduces a resolution required for an analog-to-digital converter (ADC 24) that converts the analog output signals of the IR-FPA to a digital representation. In a preferred embodiment of this invention a column CTIA readout integrated circuit architecture is used in conjunction with the adaptive feedback circuitry of this invention to provide pedestal suppression on a per-pixel basis for the IR-FPA. The use of the circuitry of this invention modifies the conventional column CTIA amplifier configuration to a configuration having an auto-zeroed charge ratioed gain stage (50). One advantage to this technique is that by suppressing the charge pedestal, the usable signal output from the IR-FPA can be brought off-chip to the readout integrated circuit at a much higher gain. As a result, the ADC requires fewer bits to resolve the useable signal information and dynamic range.
63 Citations
15 Claims
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1. An imaging device having a plurality of electromagnetic radiation detector unit cells each of which outputs an electrical signal having a magnitude that is a function of an amount of electromagnetic radiation that is detected by the unit cell, comprising:
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a plurality of amplifier means individual ones of which have an input that is switchably coupled to individual ones of a plurality of said unit cells for receiving said electrical signals therefrom;
each of said amplifier means including,first circuit means, having inputs coupled to a source of gain correction values, for selectively setting a gain of said amplifier means for each of said plurality of unit cells that are switchably coupled to said input of said amplifier means; and second circuit means, having inputs coupled to a source of offset correction values, for selectively setting an offset potential that said amplifier means subtracts from each of said electrical signals that are output by said plurality of unit cells that are switchably coupled to said input of said amplifier means. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An imaging system, comprising:
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a system controller; a two-dimensional array of radiation detectors organized as m rows and n columns, each column having a capacitively coupled transimpedance amplifier (CTIA) coupled thereto for converting a charge output by individual ones of the m radiation detectors of the column to a potential; an auto-zero charge ratioed gain stages each having an input coupled to an output of one of said CTIAs, each of said gain stages being coupled to said system controller for receiving gain correction values and offset correction values therefrom, each of said gain stages being responsive to a potential output by said CTIA for a predetermined one of the m radiation detectors of the column for modifying said potential in accordance with a gain correction value and an offset correction value received from said system controller; and an analog-to-digital converter (ADC) having an input coupled to an output of at least one of said gain stages for converting said modified potentials to a digital equivalent value, and for providing said digital equivalent values to said system controller. - View Dependent Claims (8, 9, 10, 11)
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12. A method for operating an array of radiation detectors, comprising the steps of:
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reading out uncompensated electrical signals from individual ones of the radiation detectors, the uncompensated electrical signals being generated at least partially in response to incident electromagnetic radiation; for each read-out uncompensated electrical signal, applying a gain correction and an offset correction to the read-out electrical signal in accordance with an associated gain correction value and an associated offset correction value, respectively; outputting a gain and offset compensated electrical signal; and during the step of outputting, inputting and storing a gain correction value and an offset correction value for another radiation detector. - View Dependent Claims (13, 14, 15)
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Specification