Dynamic range extension for spad-based devices

Abstract

A radiation sensitive device (420) is disclosed. The radiation sensitive device comprises a plurality of single photon avalanche diodes (SPADs) (105-0), and a processing circuit (415) configured to determine an intensity of incident radiation using at least one of the plurality of SPADs. The amount of SPADs used to determine the intensity of the incident radiation varies in relation to the intensity of the incident radiation. A related method of determining the intensity of radiation incident on such a radiation sensitive device is also disclosed, as well as the use of such a radiation sensitive device in an electronic nose or point-of-care device or for ambient light sensing.

Description

Technical Field

[0001] This disclosure pertains to the field of SPAD-based devices for measurements requiring a large dynamic range, such as point-of-care testing, electronic nose applications, and ambient radiation sensing. Background Technology

[0002] In the field of luminescent and fluorescent radiation sensors, there is a need to detect radiative emissions with a large dynamic range (DR). Such sensors can be used, for example, in point-of-care (PoC) testing, electronic nose (E-nose) type applications, or environmental radiation sensor applications.

[0003] In Proof-of-Concept (PoC) applications, the presence of biological or chemical substances in fluids or air can be detected through their interaction with complementary substances, potentially resulting in chemiluminescence or fluorescence emission. The level of emitted radiation can dynamically vary between extremely low and extremely high levels. To achieve complete signal capture, radiation sensors suitable for this application must exhibit a very high dynamic range.

[0004] A photon counter based on a single-photon avalanche diode (SPAD) provides the ability to detect very low levels of radiation by counting individual photons. The lowest level of detectable signal may be limited by noise due to the dark count rate (DCR). The highest level of detectable signal may be limited by the speed of the SPAD diode itself, the capacity of the counter associated with the SPAD, and / or the capabilities of the associated circuitry. In some applications, this can limit the dynamic range of SPAD-based sensors.

[0005] Some sensor implementations may include a large number of SPADs to improve the signal-to-noise ratio at low radiation levels. However, such a large number of SPADs may lead to an increase in associated circuitry, potentially further limiting the achievable dynamic range.

[0006] In other prior art sensor implementations, different SPAD regions can be used in combination with one or more pinholes within a single device to adjust the intensity of radiation incident on different SPAD regions. For example, stacked pinholes with displacement holes in a black medium can be implemented to reduce the intensity of incident radiation. Sensors implementing this solution may be large, may require additional components, and may exhibit a relatively poor signal-to-noise ratio.

[0007] Therefore, there is a need to provide a radiation sensor with a large dynamic range suitable for PoC testing or electronic nose applications without compromising the signal-to-noise ratio, or without requiring additional components or significantly increasing the device size.

[0008] Therefore, the purpose of at least one embodiment of at least one aspect of this disclosure is to eliminate or at least mitigate at least one of the aforementioned disadvantages of the prior art. Summary of the Invention

[0009] This disclosure belongs to the field of SPAD-based devices, and specifically relates to SPAD-based devices having a large dynamic range suitable for point-of-care testing, electronic nose applications, and environmental radiation sensing applications.

[0010] According to a first embodiment of the present disclosure, a radiation-sensitive device is provided, comprising: a plurality of SPADs; and a processing circuit configured to use at least one of the plurality of SPADs to determine the intensity of incident radiation, wherein the number of SPADs used to determine the intensity of the incident radiation varies with respect to the intensity of the incident radiation.

[0011] Advantageously, the dynamic range of radiation-sensitive devices can be increased because the amount of SPAD used to detect incident radiation can be adjusted toward the total intensity of the incident radiation without compromising the required signal-to-noise ratio at low incident radiation intensity levels, and without incurring the large die size associated with enabling all available SPADs to be used for both low-intensity and high-intensity incident radiation.

[0012] For example, at very low incident radiation levels, a large number of SPADs may be required to ensure a sufficient signal-to-noise ratio. However, due to the very low incident radiation levels, each SPAD may only require a limited number of associated circuitry to count SPAD events (e.g., incident photons). In contrast, at relatively high incident radiation levels, it has been recognized that a smaller number of SPADs can be used to achieve the required signal-to-noise ratio. Therefore, only a subset of the available SPADs will require associated circuitry capable of counting SPAD events at relatively high incident radiation levels.

[0013] The number of SPADs used to determine the intensity of incident radiation can vary inversely with the square of the intensity of the incident radiation.

[0014] In other words, most SPADs can be used to determine the intensity of incident radiation at low intensity levels, and a smaller number of available SPADs can be used to determine the intensity of incident radiation at increased intensity levels. This smaller number of SPADs can be defined by an inverse quadratic relationship with the intensity of the incident radiation. Therefore, advantageously, only a smaller number of available SPADs require associated circuitry to measure relatively high intensity incident radiation, thereby reducing overall size, cost, and power consumption while still providing a sufficient signal-to-noise ratio.

[0015] In contrast to the large number of SPADs that can be used to determine the intensity of incident radiation when the intensity is low, a small number of SPADs can be used to determine the intensity of incident radiation when the intensity is high.

[0016] Advantageously, if only a small number of SPADs are needed for high-intensity incident radiation, then only those SPADs require associated circuitry to count photon events at such high intensity levels. Therefore, the total amount of circuitry can be minimized.

[0017] Radiation-sensitive devices may include multiple counters. Each counter may be configured to store the count of photon impacts on an associated SPAD that are incident on multiple SPADs.

[0018] Advantageously, providing a counter associated with each SPAD means that the size of the counter can limit the maximum radiation intensity that each SPAD can measure, rather than the maximum measurable radiation intensity limited by a common readout rate. Advantageously, the size of such counters can be selected to limit the maximum radiation intensity that each SPAD can measure. Furthermore, by implementing a radiation-sensitive device with multiple SPADs in a single device with associated counters of different sizes, the device can be configured for a specific desired dynamic range.

[0019] Each counter can include a basic number of bits. Every 2nd 2N A counter can include a basic number of bits plus at least N bits.

[0020] That is, in some embodiments, all counters may have at least two bits. Every fourth counter may have at least three bits. Every sixteenth counter may have at least four bits. Every sixty-fourth counter may have at least five bits, and so on. Continuing the example, for a radiation intensity level that requires a five-bit counter, it may only be necessary to perform the measurement with every sixty-fourth SPAD device. Furthermore, if the radiation intensity necessitates a five-bit counter, then using only one of the sixty-four SPADs would be sufficient to achieve the desired signal-to-noise ratio.

[0021] The processing circuit can be configured to determine the intensity of the incident radiation using the following:

[0022] - A first subset of counters for radiation intensity levels above a threshold; and

[0023] - First and second subsets of counters for radiation intensity levels below a threshold.

[0024] The first subset may include all counters having a basic number of bits plus M bits. The second subset may include counters having a basic number of bits plus M-1 bits.

[0025] For example, the first subset could include one of every four counters. Therefore, in this example, only one SPAD out of every four is needed for radiation intensity levels above the threshold. The second subset could include all other counters, for example, every other three of the four counters. Therefore, all SPADs would be used for radiation intensity levels below the threshold.

[0026] The threshold can be defined by at least one overflow in the second subset of the counter.

[0027] Continuing the example above, if one or more of three out of every four counters in the second subset of the counters overflow, this indicates that the intensity of the incident radiation is sufficient such that the first subset of the counters alone is large enough to measure the intensity of the incident radiation. Therefore, subsequent measurements of the intensity of the incident radiation can be performed using only the first subset of the counters.

[0028] The processing circuitry can be configured to determine the intensity of the incident radiation using a subset of counters for radiation intensity levels above a threshold / that threshold.

[0029] The threshold can be defined by a subset of the counter / the number of bits in that subset;

[0030] The threshold can be a part of the counter, for example, if the counter reaches 25%, 50%, 75% of the maximum count, etc.

[0031] Thresholds can be additionally or alternatively defined as user-programmable values. For example, a device may have one or more programmable registers for defining one or more thresholds.

[0032] At least one counter may include sufficient bits such that the maximum count is defined by the dead time of the associated SPAD.

[0033] Advantageously, the maximum achievable dynamic range can be achieved by maximizing the size of at least one counter, such that the upper limit of the radiation intensity is defined by the dead time of the associated SPAD rather than the amount of bits in the counter.

[0034] Radiation-sensitive devices can be configured to have a common readout time interval for determining the count of photon impacts incident on each of a plurality of SPADs.

[0035] According to a second aspect of this disclosure, a method is provided for determining the intensity of radiation incident on a SPAD-based device, the method comprising changing an amount of SPAD used to determine the intensity of the incident radiation in relation to the intensity of the incident radiation.

[0036] Advantageously, the application of this method enables the device to achieve a large dynamic range without requiring a large amount of additional circuitry, and does not compromise the required signal-to-noise ratio at low incident radiation intensity levels.

[0037] The method may include the following steps: selecting a small number of SPADs to determine the intensity of the incident radiation when the intensity is high, relative to a large number of SPADs used to determine the intensity of the incident radiation when the intensity is low.

[0038] The intensity can be determined to be high when at least one counter overflows and / or when the counter exceeds a predetermined threshold.

[0039] According to a third aspect of this disclosure, a radiation-sensitive device according to the first aspect is provided for use in point-of-care testing or diagnostic applications or electronic nose applications to determine the intensity of luminescence and / or fluorescence from a sample.

[0040] In such point-of-care testing or diagnostic applications or electronic nose applications, there is a particular need to detect light emission with a very large dynamic range, because the level of chemiluminescent or fluorescent radiation emitted through the interaction between biological or chemical substances and complementary substances can vary dynamically between extremely low and extremely high levels.

[0041] According to a fourth aspect of this disclosure, an electronic nose or point-of-care device is provided, including a radiation-sensitive device according to a first aspect, wherein the radiation-sensitive device is configured to determine the intensity of luminescence and / or fluorescence from a sample.

[0042] According to the fifth aspect of this disclosure, the use of the radiation-sensitive device according to the first aspect in ambient light sensing applications is provided.

[0043] The above description of the invention is intended to be exemplary only and not restrictive. This disclosure includes one or more corresponding aspects, embodiments, or features, either alone or in various combinations, whether specifically stated (including claimed) in such combination or individually. It should be understood that features defined above according to any aspect of this disclosure or features relating to any specific embodiment of this disclosure below may be used alone or in combination with any other defined features in any other aspect or embodiment, or form another aspect or embodiment of this disclosure. Attached Figure Description

[0044] These and other aspects of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0045] Figure 1 Depicting a SPAD-based sensor architecture according to embodiments of the present disclosure;

[0046] Figure 2 Another SPAD-based sensor architecture according to embodiments of the present disclosure is described;

[0047] Figure 3 Depicting the relationship between the size of each counter and the number of each counter size in a SPAD-based sensor architecture according to embodiments of the present disclosure; and

[0048] Figure 4 A radiation-sensitive device according to an embodiment of the present invention is described. Detailed Implementation

[0049] It has been recognized that in some applications, realizing a large number of SPADs can be beneficial in order to increase the signal-to-noise ratio (SNR) in SPAD-based devices, for example, to accurately detect very low light levels. That is, such devices can realize SPAD arrays comprising hundreds or even thousands of SPADs in order to accurately measure the intensity of incident radiation with sufficient SNR.

[0050] However, the maximum radiation intensity that can be measured from a given SPAD array can be determined by its saturation level.

[0051] Saturation can occur when the photon rate reaches the limit of what a SPAD device can perform detection on its own. For example, the fastest rate at which a SPAD-based device can count photon impact events is determined by the time between the photon impact event and the SPAD's "recovery time." The "recovery time" is the time required for a given SPAD to recover and become ready again. This is referred to in the art as the "dead time." Depending on the specific quenching circuitry implemented, this recovery time can range from tens of nanoseconds to longer. For example, with a dead time of 100 nanoseconds, the maximum theoretical photon count per SPAD would be 10n per second. 7 indivual.

[0052] Saturation may occur, either additionally or alternatively, when the circuitry associated with the SPAD (e.g., the read and count circuitry attached to each SPAD) reaches its limit.

[0053] In some examples, each individual SPAD has dedicated hardware, such as a counter, for recording photon impact events. This results in a physical limit on the maximum measurable signal for a given architecture. For example, the ability of such counters and associated circuitry can be used to set a limit on the maximum measurable radiation level of a SPAD-based device. Specifically, the amount of time that any given counter must aggregate the counts of photon impact events (referred to in the art as the readout interval) can define the size of the counter associated with the SPAD.

[0054] As mentioned above, as the number of SPADs in the array increases to improve SNR, the circuitry required to maintain the counts for SPAD measurements also increases accordingly. However, a conflicting requirement is to make SPAD-based devices as small as possible, thus driving a corresponding need to make the counters as small as possible.

[0055] Figure 1 An example of a SPAD-based sensor architecture 100 including a SPAD and an associated counter is depicted according to an embodiment of the present invention. Figure 1 The SPAD-based sensor architecture 100 provided in this disclosure provides an example of determining the intensity of incident radiation, wherein the amount of SPAD used for determination varies with the intensity of the incident radiation.

[0056] It should be understood that Figure 1 These are merely exemplary embodiments and are provided for the purpose of explaining the principles of this disclosure. For example, other embodiments may include substantially larger SPAD arrays and associated counters. For instance, some embodiments may include arrays with hundreds or even thousands of SPADs. Furthermore, exemplary devices embodying this disclosure, such as sensors suitable for POC or electronic nose applications, may include multiple SPAD arrays. Additionally, the number of bits associated with each SPAD (such as the basic number of bits or the maximum number of bits) may vary compared to this example.

[0057] Figure 1 The SPAD-based sensor architecture 100 includes multiple SPADs 105-0 to 105-N. Figure 1 Each SPAD has an associated counter 110-0 to 110-N.

[0058] Counters 110-0 to 110-N can be coupled to the processing circuitry, as shown in the reference. Figure 4 A more detailed description follows. This processing circuit can be configured to use at least one of a plurality of SPADs 105-0 to 105-N to determine the intensity of the incident radiation, wherein the amount of SPADs 105-0 to 105-N used to determine the intensity of the incident radiation varies with the intensity of the incident radiation.

[0059] The embodiments of this disclosure are based on the following principle: when multiple SPADs are used together to measure light intensity, the (statistical) signal-to-noise ratio is proportional to the square root of the following two parameters: (1) the number of SPADs used in the measurement, and (2) the time window for the measurement.

[0060] Therefore, the embodiments of this disclosure effectively compromise excessive SNR for dynamic range at high radiation levels, as described in more detail below.

[0061] It has been recognized that as the measured radiation intensity (i.e., signal level) increases, the number of SPADs required to measure the signal with the desired SNR decreases.

[0062] Therefore, and as Figure 1 The example is illustrated in the SPAD-based sensor architecture 100, where the number of SPADs 105-N with large-size counters 110-N can be much smaller than the number of SPADs 105-0 with small-size counters 105-0. In fact, for each additional bit of a counter size that measures twice the signal, four times fewer SPADs may be required, as described below.

[0063] If "Num Sp "Num" represents the number of SPADs 10⁵-N required to achieve the desired SNR at the minimum radiation intensity. Therefore, when the radiation intensity level is doubled, the data from multiple SPADs equals Num. Sp / 2 2 That's enough.

[0064] therefore, Figure 1 The example embodiment illustrates a SPAD-based sensor architecture 100, which has been designed such that the number of SPADs used to measure radiation intensity decreases in an inverse quadratic relationship with the magnitude of the radiation level itself.

[0065] Continuing the example above, the total number of SPADs 105-N required for the SPAD-based sensor architecture 100 to achieve the desired SNR is "Num". Sp The SPAD-based sensor architecture 100 can be configured to have a common readout time interval for determining the count of photon impacts incident on each of the multiple SPADs 105-N. That is, a fixed readout time interval "T" may be required. read "To read data individually from all SPAD 105-N. In some example embodiments, the interval T..." read This can be defined as enabling the circuit to identify and eliminate data from one or more faulty SPADs. All SPADs 105-N require a sufficiently large (e.g., with enough bits) associated counter 110-N to retain this information without overflowing. This is represented as "N bits". base The number of bits is related to the photon impact count, as follows:

[0066]

[0067] in:

[0068] N photon,MIN It is the photon impact count at the lowest signal level; and

[0069] DCR is at interval "T"read The dark count rate over time.

[0070] For example, such as Figure 1 As depicted, SPAD 105-0 has an associated counter 110-0, which includes two bits 110-0A and 110-0B. These two bits 110-0A and 110-0B represent N bits. base Using two bits, a total of four binary counts can be achieved. That is, the SPAD 105-0 can count a total of three photon impact events before saturation and possible overflow, such as lost photon impact events or flips, depending on the chosen implementation.

[0071] If the signal level increases due to increased radiation intensity incident on the SPAD array, then such a two-bit counter 110-0 will begin to saturate or overflow. Therefore, more bits may be needed to prevent saturation or overflow. However, as mentioned above, it has been recognized that at higher incident radiation intensity levels, a lower number of SPADs can be used to achieve the desired signal-to-noise ratio. That is, fewer SPADs 110-N may be needed to detect an increase in signal with the desired SNR.

[0072] For example, if the signal is doubled, the number of SPAD 105-N units required to measure the signal is reduced by a factor of four, for example, 2. 2 times.

[0073] In order to utilize the reduced number of SPADs to measure the increased signal, the size of the counter 110-N associated with each SPAD 105-N must be increased accordingly. By increasing the counter by one bit, the maximum count is doubled. That is, by increasing the counter by one bit, the total count corresponding to the measured signal and any dark count contribution is doubled.

[0074] For example, in Figure 1 As can be seen, each of the four SPADs 105-3, 105-7, 105-11, and 105-15 has an associated counter comprising three bits. For example, the fourth SPAD 105-3 has an associated counter 110-3 comprising three bits: 110-3A, 110-3B, and 110-3C. Therefore, the fourth SPAD 105-3 can count a total of seven photon impact events before saturation or overflow, for example, 2. 3 -1.

[0075] In other words, with no change in noise level, by adding additional bits, the signal level at which counter 110 saturates is at least doubled. Therefore, whenever a bit is added to counter 110-N associated with SPAD 105-N, the number of SPADs required to measure the intensity of incident radiation is reduced by a factor of 4.

[0076] Therefore, the described architecture requires a basic number of bits, N bits. base For example, all Num Sp The smallest counter size of a SPAD is sufficient to support twice the minimum signal level. This can be achieved by waiting...

[0077] Equation 2 describes this, where:

[0078]

[0079] In other words, in the embodiments of this disclosure, each of the four SPADs 105-N will require an additional bit in the associated counters 110-N.

[0080] Turn to Figure 1 In the example embodiment, it can be seen that all SPADs 105-0 to 105-N have associated counters 110-0 to 110-N, where "Nbits" base "As the basic number of bits."

[0081] Only a quarter of SPADs (e.g., SPAD 105-3, 105-7, 105-11, 105-15) include an extra bit in their associated counters 110-3, 110-7, 110-11, 110-15. That is, each of counters 110-3, 110-7, 110-11, 110-15 includes at least three bits.

[0082] One-sixteenth of a SPAD (e.g., SPAD 110-15) will have two extra bits. That is, SPAD 110-15 includes at least four bits.

[0083] For the sake of simplicity, Figure 1 The SPAD-based sensor architecture 100 is depicted as having only 16 SPADs 105-0 to 105-N, each SPAD having an associated counter 110-0 to 110-N. It should be understood that for larger SPAD arrays, the above sequence will continue. That is, one-sixty-fourth of SPADs 105-0 to 105-N will have three additional bits, for example, a total of 5 bits, and so on.

[0084] Therefore, according to Figure 1The SPAD-based sensor architecture 100 implemented in the embodiments can meet the SNR requirements when the intensity of incident radiation increases and the SPAD is gradually reduced.

[0085] Therefore, the effective dynamic range of this SPAD-based sensor architecture is increased within the constraints imposed by size and power limitations. In other words, the disclosed SPAD-based sensor architecture 100 maximizes the achievable dynamic range while maintaining sufficient SNR without exceeding grain size and / or power constraints.

[0086] Figure 2 Another SPAD-based sensor architecture 200 is depicted according to embodiments of the present disclosure. Figure 2 The SPAD-based sensor architecture 200 shares many features with... Figure 1 The SPAD-based sensor architecture 100 has the same characteristics, therefore such characteristics are not described in detail for the sake of brevity. However, for illustrative purposes, an array of sixty-four SPADs 205-0 to 205-N and associated counters 210-0 to 210-N are shown. The principles described above are implemented, wherein: the basic number of bits for all counters is two bits, every fourth SPAD has an associated counter including one additional bit, and every sixteenth SPAD has an associated counter including two additional bits (e.g., four bits in total).

[0087] When the required number of SPADs becomes one or fewer, it can be inferred that all radiation intensities above that level require only one SPAD to have reliable signal readout, e.g., a sufficient signal-to-noise ratio. Therefore, in some embodiments, this final SPAD may have an associated counter with the largest possible capacity required to support the maximum possible dynamic range. In this case, the counter size can be made large enough that the maximum counting bottleneck becomes the speed of the SPAD diode itself, i.e., the aforementioned dead time.

[0088] Refer again Figure 2 As can be seen from the example embodiment, the sixty-fourth SPAD 205-63 has an associated counter 210-63, which has:

[0089] The basic quantity of 210-63A and 210-63B is 2.

[0090] -Based on the four additional bits 210-63C, 210-63D, 210-63E, 210-63F of the above sequence

[0091] - Example: Two additional bits, 210-63G and 210-63H, are used to maximize the dynamic range of the SPAD-based sensor architecture 200.

[0092] Figure 3 The relationship between the size of each counter and the number of counters is depicted in another SPAD-based sensor architecture according to an embodiment of the present invention. In the described example embodiment, this other SPAD-based sensor architecture includes an array of 256 SPADs and associated counters. The basic number of bits is Nbits. base (For example, the smallest counter size sufficient to support twice the minimum signal level of all SPADs) is two. It can be seen that all 256 counters include at least two bits. Using two bits, each counter can count a total of 3 photon impact events.

[0093] One-quarter of the 256 counters includes an additional bit, so the sixty-four counters can count a total of seven photon impact events.

[0094] One-sixteenth of the 256 counters includes two additional bits, so sixteen of the counters can count a total of 15 photon impact events.

[0095] One-sixty-fourth of the 256 counters includes three additional bits, so four of the counters can count a total of 31 photon impact events.

[0096] That is to say, every 2nd 2N Each counter consists of a basic number of bits plus N bits.

[0097] One of the counters has at least four additional bits, so this one of the counters can count a total of 63 photon impact events. (See above for reference.) Figure 2 As described, when the number of required SPADs becomes one or less, in some embodiments, the final SPAD may have an associated counter with the largest possible capacity required to support the maximum possible dynamic range.

[0098] Figure 3 The graph (which has a logarithmic scale on both axes) depicts the relationship between the number of counters and the number of bits included in each counter, where the number of counters corresponds to the number of SPADs used. The graph shows, for example, how all 256 counters include 2 bits capable of counting up to 4, while only 4 counters include up to 4 bits capable of counting up to 15 photon impact events. That is, in some embodiments, the number of SPADs used to determine the intensity of the incident radiation varies in an inverse quadratic relationship with the intensity of the incident radiation. Therefore, most SPADs can be used to determine the intensity of the incident radiation at low intensity levels, and a smaller number of available SPADs can be used to determine the intensity of the incident radiation at increasing intensity levels.

[0099] Figure 4 An apparatus 400 including a radiation-sensitive device 420 according to an embodiment of the present invention is depicted. In some example embodiments, the apparatus 400 may be an apparatus for point-of-care (PoC) testing or electronic nose (E-nose) type applications or environmental radiation sensor applications.

[0100] The radiation-sensitive device 420 includes a plurality of SPADs 405. The plurality of SPADs 405 may be arranged as one or more arrays of SPADs 405.

[0101] The radiation-sensitive device 420 also includes a plurality of counters 410. Each of the plurality of counters 410 is associated with a SPAD in a plurality of SPADs 405, as referenced above. Figure 1 and Figure 2 As described. SPAD 405 and the associated counter 410 can be based on Figure 1 and Figure 2 The SPAD-based sensor architectures 100 and 200 are arranged, for example, where each second 2N Each counter 410 includes a basic number of bits plus N bits.

[0102] The radiation-sensitive device 420 also includes processing circuitry 415. In some embodiments, processing circuitry 415 may be configured to control a plurality of SPADs 405. For example, in some embodiments, processing circuitry 415 may be configured to control the quenching of SPADs 405, and / or reset or enable one or more of SPADs 405. Processing circuitry 415 may also be configured to detect one or more faulty SPADs 405.

[0103] In some embodiments, the processing circuit 415 may be configured to read the counter 410. In some embodiments, the processing circuit 415 may also be configured to reset the counter 410 as needed. The processing circuit 415 may include at least one of the following: a CPU, a microcontroller, a state machine, combinational logic, etc.

[0104] In some embodiments, the processing circuit 415 may be configured to use at least one of a plurality of SPADs 405 to determine the intensity of the incident radiation, wherein the number of SPADs used to determine the intensity of the incident radiation varies with respect to the intensity of the incident radiation.

[0105] In some embodiments, an aperture, lens, optical cover, grating, or one or more other optical devices may be disposed between SPAD 405 and the radiation source. Such devices may be configured, for example, to focus and / or diffuse radiation incident on SPAD 405. In some embodiments, one or more apertures may be stacked to form a stack of displaced apertures or pinholes. Such a stack may be disposed on or adjacent to SPAD 405. In such embodiments, at least some of SPADs 405 may be subjected to incident radiation of lower intensity than other SPADs of the radiation-sensitive device 420. By using such displaced apertures, in conjunction with any of the above-described techniques, the dynamic range of the radiation-sensitive device 420 may be further increased.

[0106] Although this disclosure has been described with reference to specific embodiments as described above, it should be understood that these embodiments are merely illustrative and the claims are not limited to those embodiments. Modifications and substitutions will be able to be made by those skilled in the art in light of this disclosure, and such modifications and substitutions are considered to fall within the scope of the appended claims. Each feature disclosed or shown in this specification may be incorporated in any embodiment, either alone or in any suitable combination with any other feature disclosed or shown herein.

[0107] List of reference numerals

[0108] 100 SPAD-based sensor architectures

[0109] 105-0 to 105-N SPAD

[0110] 110-0 to 110-N counters

[0111] 200 SPAD-based sensor architectures

[0112] 205-0 to 205-N SPAD

[0113] 210-0 to 205-N counters

[0114] 400 device

[0115] 405 SPAD

[0116] 410 counter

[0117] 415 Processing Circuit

[0118] 420 Radiation-sensitive equipment

Claims

1. A radiation-sensitive device (420), comprising: Multiple single-photon avalanche diodes (SPADs) (10⁵-0 to 10⁵-N); as well as The processing circuit (415) is configured to use at least one of the plurality of SPADs to determine the intensity of the incident radiation, wherein the number of SPADs used to determine the intensity of the incident radiation varies with the intensity of the incident radiation, and wherein the plurality of SPADs are associated with counters of different sizes.

2. The radiation-sensitive device (420) according to claim 1, wherein the number of SPADs (10⁵-0 to 10⁵-N) used to determine the intensity of the incident radiation varies inversely proportional to the square of the intensity of the incident radiation.

3. The radiation-sensitive device (420) according to claim 1 or 2, wherein a small number of SPADs (10⁵-0 to 10⁵-N) are used to determine the intensity of the incident radiation when the intensity is high, in contrast to a large number of SPADs used to determine the intensity of the incident radiation when the intensity is low.

4. The radiation-sensitive device (420) according to claim 1 or 2, comprising a plurality of counters (110-0 to 110-N), wherein each counter is configured to store a count of photon impacts incident on an associated SPAD among the plurality of SPADs (105-0 to 105-N).

5. The radiation sensitive device (420) of claim 4, wherein each counter (110-0 to 110-N) comprises a base number of bits, and wherein every 2 2N nd counter comprises the base number of bits plus at least N bits.

6. The radiation-sensitive device (420) of claim 4, wherein the processing circuitry is configured to determine the intensity of the incident radiation using a subset of the counters (110-0 to 110-N) for radiation intensity levels above a threshold.

7. The radiation-sensitive device (420) according to claim 6, wherein the threshold is defined as follows: - A subset of the counter / the number of bits in the subset; and / or - User-programmable values.

8. The radiation-sensitive device (420) according to claim 4, wherein at least one counter (110-0 to 110-N) includes sufficient bits such that the maximum count is defined by the dead time of the associated SPAD (105-0 to 105-N).

9. The radiation-sensitive device (420) according to claim 1 or 2, wherein the radiation-sensitive device (420) is configured to have a common readout time interval for determining the count of photon impacts incident on each of the plurality of SPADs (105-0 to 105-N).

10. A method for determining the intensity of radiation incident on a device based on a single-photon avalanche diode (SPAD), the method comprising changing an amount of SPAD (10⁵⁻⁰ to 10⁵⁻⁴) used to determine the intensity of the incident radiation in relation to the intensity of the incident radiation, wherein, The SPAD is associated with counters of different sizes.

11. The method of claim 10, comprising the following steps: In contrast to a large number of SPADs used to determine the intensity of the incident radiation when the intensity is low, a small number of SPADs (10⁵⁻⁰ to 10⁵⁻⁴N) are selected to determine the intensity of the incident radiation when the intensity is high.

12. The method of claim 11, wherein the intensity is determined to be high when at least one counter (110-0 to 110-N) overflows and / or when the counter exceeds a predetermined threshold.

13. The use of a radiation-sensitive device (420) according to any one of claims 1 to 9 in a point-of-care testing or diagnostic application or an electronic nose application to determine the intensity of luminescence and / or fluorescence from a sample.

14. An electronic nose or care point device comprising a radiation-sensitive device (420) according to any one of claims 1 to 9, wherein the radiation-sensitive device is configured to determine the intensity of luminescence and / or fluorescence from a sample.

15. Use of a radiation-sensitive device (420) according to any one of claims 1 to 9 in an ambient light sensing application.

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