Methods and apparatus for in-pixel filtering in focal plane arrays including apparatus and method for counting pulses representing an analog signal
First Claim
1. An apparatus for counting pulses representing an analog signal, the apparatus comprising:
- (A) a photodetector array comprising at least one photodetector to produce a photocurrent in response to detection of light; and
(B) an integrated circuit operably coupled to the photodetector array, the integrated circuit comprising a plurality of unit cells, wherein at least one unit cell in the plurality of unit cells comprises;
(i) a converter to convert the photocurrent from the at least one photodetector in the photodetector array to series of pulses;
(ii) a first counter to count first pulses in the series of pulses in response to a first clock selection signal; and
(iii) a second counter to count second pulses in the series of pulses in response to a second clock selection signal.
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Accused Products
Abstract
Digital focal plane arrays (DFPAs) with multiple counters per unit cell can be used to convert analog signals to digital data and to filter the digital data. Exemplary DFPAs include two-dimensional arrays of unit cells, where each unit cell is coupled to a corresponding photodetector in a photodetector array. Each unit cell converts photocurrent from its photodetector to a digital pulse train that is coupled to multiple counters in the unit cell. Each counter in each unit cell can be independently controlled to filter the pulse train by counting up or down and/or by transferring data as desired. For example, a unit cell may perform in-phase/quadrature filtering of homodyne- or heterodyne-detected photocurrent with two counters: a first counter toggled between increment and decrement modes with an in-phase signal and a second counter toggled between increment and decrement modes with a quadrature signal.
64 Citations
20 Claims
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1. An apparatus for counting pulses representing an analog signal, the apparatus comprising:
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(A) a photodetector array comprising at least one photodetector to produce a photocurrent in response to detection of light; and (B) an integrated circuit operably coupled to the photodetector array, the integrated circuit comprising a plurality of unit cells, wherein at least one unit cell in the plurality of unit cells comprises; (i) a converter to convert the photocurrent from the at least one photodetector in the photodetector array to series of pulses; (ii) a first counter to count first pulses in the series of pulses in response to a first clock selection signal; and (iii) a second counter to count second pulses in the series of pulses in response to a second clock selection signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for counting pulses representing an analog signal, the apparatus comprising:
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(A) producing a photocurrent, with at least one photodetector in a photodetector array, in response to detection of light; and (B) converting the photocurrent to a series of pulses with a converter in a unit cell in a plurality of unit cells operably coupled to the photodetector array; (C) counting first pulses in the series of pulses with a first counter in the unit cell in response to a first clock selection signal; and (D) counting second pulses in the series of pulses with a second counter in the unit cell in response to a second clock selection signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An apparatus for counting pulses representing an amplitude of optical radiation, the apparatus comprising:
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a plurality of photodetectors comprising at least one photodetector to produce an analog signal representing the amplitude of the optical radiation; and an integrated circuit operably coupled to the plurality of photodetectors, the integrated circuit comprising a plurality of unit cells, wherein at least one unit cell in the plurality of unit cells comprises; a converter to convert the analog signal from the at least one photodetector in the photodetector array to series of pulses; a plurality of counters comprising at least one counter, operably coupled to the converter, to count pulses in the series of pulses and to read-out a count representing the pulses in the series of pulses in response to a read-out clock; and a first multiplexer, operably coupled to the converter and to the at least one counter in the plurality of counters, to couple one of the series of pulses and the read-out clock to the plurality of counters in response to a clock selection signal. - View Dependent Claims (18, 19, 20)
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Specification