SPAD detector having modulated sensitivity
First Claim
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1. A single-photon avalanche diode (SPAD) detector, comprising:
- a pixel array comprising multiple lines of pixels, each pixel comprising a SPAD;
a time-to-digital converter (TDC) array circuit operably connected to the pixel array, the TDC array circuit comprising an array of TDC circuits with a subset of the TDC circuits operably connected to each respective line of pixels; and
a memory operably connected to the TDC array circuit, the memory configured to store a non-uniform histogram that comprises;
a first bin having a first width, the first bin representing a first count of photons having times of flight within a first range of times of flight; and
a second bin having a second width different from the first width, the second bin representing a second count of photons having times of flight within a second range of times of flight different from the first range of times of flight, wherein the first bin provides the SPAD detector with a first sensitivity to photons and the second bin provides the SPAD detector with a second sensitivity to photons that is different from the first sensitivity.
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Abstract
The sensitivity of one or more single-photon avalanche diodes (SPAD) in a SPAD detector is modulated over time. The sensitivity of all of the SPADs may be modulated, or the sensitivity of one section of the SPADs can be modulated differently from another section of the SPADs. Various techniques for modulating the sensitivity are disclosed.
279 Citations
23 Claims
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1. A single-photon avalanche diode (SPAD) detector, comprising:
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a pixel array comprising multiple lines of pixels, each pixel comprising a SPAD; a time-to-digital converter (TDC) array circuit operably connected to the pixel array, the TDC array circuit comprising an array of TDC circuits with a subset of the TDC circuits operably connected to each respective line of pixels; and a memory operably connected to the TDC array circuit, the memory configured to store a non-uniform histogram that comprises; a first bin having a first width, the first bin representing a first count of photons having times of flight within a first range of times of flight; and a second bin having a second width different from the first width, the second bin representing a second count of photons having times of flight within a second range of times of flight different from the first range of times of flight, wherein the first bin provides the SPAD detector with a first sensitivity to photons and the second bin provides the SPAD detector with a second sensitivity to photons that is different from the first sensitivity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A pixel in a single-photon avalanche diode (SPAD) detector, the pixel comprising:
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a SPAD operably connected between a node and a first voltage supply; a gating transistor operably connected between the node and a reference voltage supply; and a quenching transistor operably connected between the node and a second voltage supply, wherein the gating transistor is configured to receive a gating signal that enables an operation of the SPAD at a first time and subsequently disables the operation of the SPAD at a second time; a gate of the quenching transistor is connected to a first switch and a second switch; the first switch is connected to a first quenching signal; and the second switch is connected to a second quenching signal that is different from the first quenching signal. - View Dependent Claims (13, 14, 15)
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16. A single-photon avalanche diode (SPAD) detector, comprising:
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a pixel array comprising a plurality of pixels arranged in a reference sub-array and an imaging sub-array, each pixel comprising a SPAD and a quenching transistor operably connected to the SPAD; a constant voltage source operably connected to a terminal of each quenching transistor in the reference sub-array; a switch array operably connected to the pixel array, wherein each switch in the switch array is connected to a respective line of pixels in the imaging sub-array; and a variable signal source operably connected to a terminal of each quenching transistor in the pixels in each line of pixels in the imaging sub-array through a respective switch in the switch array. - View Dependent Claims (17, 18)
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19. A single-photon avalanche diode (SPAD) detector, comprising:
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a pixel array comprising a plurality of pixels, each pixel comprising a SPAD and a quenching transistor operably connected to the SPAD; a switch array operably connected to the pixel array; a current source operably connected to a gate of each quenching transistor in each line of pixels in the pixel array through a respective first switch in the switch array; and a variable signal generator operably connected to a terminal of each quenching transistor in each line of pixels in the pixel array through a respective second switch in the switch array. - View Dependent Claims (20)
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21. A method for operating a single-photon avalanche diode (SPAD) detector, the SPAD detector comprising a pixel array that includes a reference sub-array of reference pixels and an imaging sub-array of imaging pixels, the method comprising:
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detecting a start time to enable an operation of an imaging SPAD in an imaging pixel in the imaging sub-array using a reference SPAD in a reference pixel in the reference sub-array; in response to detecting the start time, enabling the operation of the imaging SPAD such that the imaging SPAD is operable to detect photons; determining, for each detected photon, a respective time of flight; and constructing a non-uniform histogram based on a time of flight of each detected photon, wherein the non-uniform histogram comprises; a first bin having a first width, the first bin representing a first count of photons having times of flight within a first range of times of flight; and a second bin having a second width different from the first width, the second bin representing a second count of photons having times of flight within a second range of times of flight different from the first range of times of flight, the first bin providing the SPAD detector with a first sensitivity to photons and the second bin providing a second sensitivity to photons that is different from the first sensitivity. - View Dependent Claims (22, 23)
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Specification