Dynamic range extension for spad-based devices

Abstract

A radiation-sensitive device (320) is disclosed. The device includes an array of single-photon avalanche diodes (105) and a circuit (115) configured to measure the intensity of incident radiation from the array of SPADs using multiple different measurement windows to provide multiple associated results. The circuit is configured to determine the intensity of the incident radiation based on one of the multiple results, the selection of which is determined by whether the result exceeds a maximum count, which is at least partially limited by the duration of the measurement window associated with the result. An associated method for increasing the dynamic range of a radiation-sensitive device including an array of SPADs is also disclosed.

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, which may result in chemiluminescence or fluorescence emission. The level of emitted radiation can vary dynamically 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 detectable signal level may be limited by noise due to the dark count rate (DCR). The highest detectable signal level can 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, this large number of SPADs can 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 combined with one or more pinholes for use in 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 such a solution may be large, may require additional components, and may exhibit a relatively poor signal-to-noise ratio.

[0007] Therefore, it is desirable to provide a radiation sensor that has 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 a significant increase in 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 pertains to the field of SPAD-based devices, and specifically relates to SPAD-based devices having a wide dynamic range suitable for point-of-care testing, electronic nose applications, and ambient radiation sensing applications.

[0010] According to a first aspect of this disclosure, a radiation-sensitive device is provided, comprising an array of single-photon avalanche diodes (SPADs) and circuitry configured to measure the intensity of incident radiation from the array of SPADs using a plurality of different measurement windows to provide a plurality of associated results. The circuitry is configured to determine the intensity of the incident radiation based on one of the plurality of results, the selection of which result is determined by whether the result exceeds a maximum count, the maximum count being at least partially defined by the duration of the measurement window associated with the result.

[0011] Advantageously, by using multiple different measurement windows, i.e., measurement time windows, the intensity of the incident radiation can be measured in multiple different ways, where the signal-to-noise ratio (SNR) of each measurement can differ at least in part depending on the duration of the measurement window. As described in more detail below, a portion of the measurement period associated with each measurement window can also be selected. The combination of the duration of the measurement window and a portion of the measurement period determines the total SNR of a given measurement. Furthermore, relatively high-intensity incident radiation can be measured by using relatively short measurement windows, and relatively low-intensity incident radiation can be measured by using relatively long measurement windows. Measurements using such different measurement windows can extend the effective dynamic range of radiation-sensitive devices. Moreover, it has been recognized that under relatively high-intensity incident radiation, there is sufficient signal strength for low SNR measurements to be sufficient. Therefore, the result among multiple results can be selected based on the intensity of the incident radiation, thereby effectively balancing the achievable SNR of the dynamic range where a high SNR capability may not be required under relatively high-intensity incident radiation.

[0012] In other words, advantageously, the amount of time a given SPAD among a plurality of SPADs can be used to detect photon impacts can be predefined according to defined signal-to-noise ratio and dynamic range requirements.

[0013] Since each SPAD can record only a single photon impact event between each readout cycle, having a relatively long measurement window during periods of relatively high-intensity incident radiation can result in a large number of SPADs not recording photon impact events, thus limiting the measurable radiation intensity. By dividing the measurement cycle into portions with measurement windows that are related to the intensity of the incident radiation, the number of SPADs that do not record photon impact events can be minimized, and thus the dynamic range of the radiation-sensitive device can be increased while maintaining a sufficient signal-to-noise ratio.

[0014] The maximum count can be limited by the duration of the measurement window associated with the result and the readout rate of the SPAD.

[0015] For example, for a SPAD array comprising 100 SPADs and a readout rate of 10 MHz, each SPAD can perform up to 100,000 counts per second. The duration of the measurement window can correspond to a scaling factor applied to the maximum count, as described in more detail below.

[0016] The circuit can be configured to scale at least one result using a corresponding weighting factor, the magnitude of which corresponds to the duration of the measurement window associated with the result.

[0017] Continuing with the previous example, if the duration of a portion of the 1-second measurement period is 0.9 seconds, the measured count can be scaled by a weighting factor of 1 / 0.9 to provide a maximum count of 100,000.

[0018] The duration of the measurement window in each consecutive segment of the measurement cycle can vary by a factor of 4. For example, the duration of the measurement window in each consecutive segment of the measurement cycle can be increased by a factor of four or decreased to a quarter. The duration of the measurement window in each consecutive segment of the measurement cycle can be increased by a factor of four or decreased to a quarter for every doubling of the signal (e.g., an increase in the intensity of the incident radiation).

[0019] The circuit can be configured to arrange the array of SPADs to measure incident radiation within a relatively short measurement window during a smaller portion of the measurement period, which is smaller than the portion of the measurement period during which the array of SPADs measures incident radiation with a relatively long measurement window.

[0020] Advantageously, as signal strength increases, for example, as the intensity of incident radiation increases, the duration of a portion of the measurement period with a relatively short measurement window can be reduced. Similarly, at low signal levels, such as under low-intensity incident radiation, a larger portion of the measurement period may need to include a longer measurement window to ensure a sufficient signal-to-noise ratio.

[0021] The duration of each measurement window can be programmable.

[0022] The duration of each part of the measurement cycle can be programmable.

[0023] Advantageously, the duration of each portion of the measurement window and / or measurement cycle can be defined by one or more user-programmable fields, thereby achieving a programmable trade-off between dynamic range and achievable signal-to-noise ratio. For example, the device may have one or more programmable registers for defining one or more durations and / or one or more readout rates.

[0024] The duration of the measurement window can be different in each part of the measurement cycle.

[0025] Each of the multiple SPADs may have an associated single-bit counter for recording photon impacts.

[0026] Advantageously, the overall size of radiation-sensitive devices can be minimized by associating only a single-bit counter with each SPAD. An alternative architecture could employ a multi-bit counter per SPAD to minimize the likelihood of missing photon impact events, but this alternative architecture may incur costs associated with a larger overall device area.

[0027] It should be understood that a single-bit counter can be a latch or a switch. That is, in some embodiments, a single-bit counter can be one or more circuit components configured to record events (e.g., latch signals). Such a single-bit counter can be cleared (e.g., reset) at a rate limited by the readout rate of the SPAD.

[0028] Furthermore, the term "readout" will be understood as corresponding to the process of determining whether a single-bit counter has been set (e.g., the latch has latched a photon impact event). For example, an array of readout SPADs would include circuitry to determine which counters among the counters associated with the SPAD have counted (e.g., latched) photon impact events.

[0029] The read rate can depend on the amount of SPAD to be read.

[0030] According to a second aspect of this disclosure, a method is provided to increase the dynamic range of a radiation-sensitive device including an array of SPADs. The method includes the step of measuring the intensity of incident radiation from the array of SPADs using multiple different measurement windows to provide a plurality of associated results. The method includes the step of determining the intensity of the incident radiation from one of the plurality of results, the selection of the result being determined by whether the result exceeds a maximum count, which is at least partially defined by the duration of the measurement window associated with the result.

[0031] The method may include the step of selecting and / or programming the duration of each measurement window among multiple measurement windows.

[0032] The step of measuring the intensity of incident radiation from an array of SPADs using multiple different measurement windows may include using a relatively short measurement window within a smaller portion of the measurement period, which is smaller than a portion of the measurement period having a relatively long measurement window.

[0033] The method may include steps of selecting and / or programming the duration of a portion of the measurement cycle associated with each measurement window.

[0034] According to a third aspect of this disclosure, the use of a radiation-sensitive device according to the first aspect in point-of-care testing or diagnostic applications or electronic nose applications is provided to determine the intensity of luminescence and / or fluorescence from a sample.

[0035] In such point-of-care testing or diagnostic applications or electronic nose applications, there is a particular need to detect radiation emissions 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.

[0036] According to a fourth aspect of this disclosure, an electronic nose or point-of-care device is provided, comprising a radiation-sensitive device according to the first aspect, wherein the radiation-sensitive device is configured to determine the intensity of luminescence and / or fluorescence from a sample.

[0037] According to the fifth aspect of this disclosure, the use of the radiation-sensitive device according to the first aspect in environmental radiation sensing applications is provided.

[0038] Radiation-sensitive devices, implemented in imaging devices such as cameras (e.g., those on smartphones), are used to determine ambient radiation levels. The determined ambient radiation levels can be used to adjust images captured by the imaging device. The determined ambient radiation levels can also be used to configure the imaging device, such as to control the operation of aperture, flash, etc.

[0039] Radiation-sensitive devices can be used to determine the level of ambient radiation in order to adjust the brightness of a screen or monitor.

[0040] 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 hereinafter in relation to any particular embodiment of this disclosure may be used alone or in combination with any other defined features in any other aspect or embodiment, or to form further aspects or embodiments of this disclosure. Attached Figure Description

[0041] These and other aspects of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0042] Figure 1 Depicting a SPAD-based sensor architecture according to embodiments of the present disclosure;

[0043] Figure 2 An example measurement cycle of a radiation-sensitive device according to an embodiment of the present disclosure is described;

[0044] Figure 3 A radiation-sensitive device according to embodiments of the present disclosure is depicted; and

[0045] Figure 4 A method for increasing the dynamic range of a radiation-sensitive device according to embodiments of the present disclosure is described. Detailed Implementation

[0046] It has been recognized that in some applications, implementing a large number of SPADs can be beneficial to increase the signal-to-noise ratio (SNR) in SPAD-based devices, such as for the accurate detection of very low light levels. That is, such devices can implement SPAD arrays comprising hundreds or even thousands of SPADs in order to accurately measure the intensity of incident radiation with a sufficient SNR.

[0047] However, the maximum radiation intensity that can be measured from a given SPAD array can be determined by its saturation level.

[0048] Saturation can occur when the photon rate reaches the limit of the detection rate that the SPAD device itself can perform. 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 be 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, for a dead time of 100 nanoseconds, the maximum theoretical photon count per SPAD would be 10-1. 7 Every second.

[0049] 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 limits.

[0050] In some examples, each individual SPAD has a dedicated readout bandwidth for recording photon impact events. This results in a physical limitation on the maximum measurable signal for a given architecture.

[0051] For example, in some examples, each SPAD has only a single latch to store photon impact events, such as a single-bit counter. This latch can be reset each time it is read. The minimum read interval is the time required to read all such latches.

[0052] Figure 1 An example of a SPAD-based sensor architecture 100 comprising 100 SPADs and associated single-bit counters according to embodiments of the present disclosure is described. Figure 1 The SPAD-based sensor architecture 100 provided in this disclosure exemplifies the use of a radiation-sensitive device comprising multiple SPADs to determine the intensity of incident radiation, wherein circuitry is configured to measure the intensity of incident radiation from an array of SPADs using multiple different measurement windows to provide multiple associated results. As will be described in more detail below, in some embodiments, the circuitry may be configured to determine the intensity of the incident radiation based on one of the multiple results, the selection of which is determined by whether the result exceeds a maximum count. The maximum count may be limited at least in part by the duration of the measurement window associated with the result.

[0053] 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 arrays of substantially larger SPADs and associated single-bit 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 arrays of SPADs.

[0054] Figure 1 The SPAD-based sensor architecture 100 includes multiple SPADs 105-0 to 105-99. For illustrative purposes only, the SPADs 105-0 to 105-99 are arranged in a 10×10 array. Figure 1 Each SPAD has an associated single-bit counter 110-0 to 110-99. In some embodiments, the single-bit counters 110-0 to 110-99 can be implemented using latches, switches, etc.

[0055] Single-bit counters 110-0 to 110-99 are depicted as being coupled to processing circuitry 115.

[0056] This processing circuit 115 can be configured to determine the intensity of incident radiation using at least one of a plurality of SPADs 105-0 to 105-99, wherein the processing circuit 115 is configured to measure the intensity of incident radiation from the array of SPADs 105-0 to 105-99 using a plurality of different measurement windows to provide a plurality of associated results.

[0057] The embodiments of this disclosure are based on the principle that when multiple SPADs are used together to measure light intensity, the (statistical) signal-to-noise ratio is proportional to the measurement time window (e.g., interval) in which the measurement is performed.

[0058] Therefore, as described in more detail below, embodiments of this disclosure effectively balance the SNR for dynamic range (which is excessive at high radiation levels). It has been recognized that as the intensity of the radiation being measured (i.e., the signal level) decreases, the size of the measurement time window in which the measurement must be performed increases. Conversely, at high levels of incident radiation, a minimal measurement window may be required to ensure sufficient SNR.

[0059] For including "Num" SPAD "A radiation-sensitive device for each SPAD, and the time required to read out and reset the latch associated with each SPAD is "T 1_SPAD The total readout time for these multiple SPADs is Num SPAD ×T 1_SPAD .

[0060] However, even if reading all SPADs takes the minimum time Num Sp *T 1_SPAD Even under high-intensity incident radiation, SPAD can remain inactive for a portion of that time window.

[0061] Consider an increase in the intensity of the incident radiation to the point that more than one photon strikes “Num”. Sp *T 1_SPAD An example where the probability of SPAD becomes relatively high within a window of time Num. In such an example, SPAD can only be used within a time window Num. Sp *T 1_SPAD Only a quarter of them remained active.

[0062] Based on the Poisson statistical properties of photon incidence, the probability of more than one photon hitting the SPAD and being missed within the time window is now reduced to near zero.

[0063] In such an example, each detected photon will be weighted at 4 to account for the fact that the detection window is only a quarter of the total readout time.

[0064] Embodiments of this disclosure can employ the technology in a non-adaptive manner without requiring any dynamic changes to the operating timing of the device, which may depend on the intensity of the incident radiation.

[0065] For example, refer to again Figure 1An exemplary SPAD-based sensor architecture 100 is depicted, which is an array of 100 SPADs 105-0 to 105-99.

[0066] With 100 SPADs and a readout rate of 10 MHz, the time required to read the entire array will be 100 / 10. 6 = 10 microseconds. Therefore, each SPAD can theoretically detect 100,000 counts per second.

[0067] For example, if implemented Figure 1 The SPAD-based sensor architecture 100 radiation-sensitive device is configured to operate in the first 0.9 seconds of each second, where the measurement window covers the entire 10µs, so that each photon detected in this period will be weighted as 1.

[0068] To extrapolate this number to 1 second, multiply it by 1 / 0.9, since only 0.9 is used per second. Therefore, the result of a maximum count of 100,000 is based on this measurement. For illustrative purposes, this is referred to as "Result X".

[0069] Radiation-sensitive devices can also be configured to operate in the last 0.1 seconds of each second, where the measurement window is only 1 µs, for example, only one-tenth of a 10 µs readout time. In such an example, the theoretical maximum of 10,000 counts per SPAD per second is achievable, for example, 0.1 / 10 microseconds.

[0070] Since the SPAD is active for only 1 / 10 of the total time, each detected photon is weighted by a factor of 10. Furthermore, to extrapolate this from 0.1 seconds to 1 second, an additional factor of 10 is applied. Since the theoretical maximum count of 10,000 can be measured within that 0.1 second, the application of the weighting factor effectively translates this to 1,000,000 counts per SPAD per second. For illustrative purposes, this is referred to as "Result X".

[0071] Therefore, two results can be generated: result X with a maximum count of 100,000 and result Y with a maximum count of 1,000,000.

[0072] The result Y may be much noisier than the result X because the result Y is based on an effective time window of 1 / 100th of a second. Therefore, for signal values ​​below 100,000, the result X will be used to determine the intensity of the incident radiation. For higher counts, the result Y can be used. This is because, since the intensity of the incident radiation is so high, for example, greater than 100,000 counts, the higher noise due to the reduced time window for the result Y becomes irrelevant. That is, a sufficient signal-to-noise ratio exists.

[0073] Therefore, the selection of an outcome (e.g., outcome X or outcome Y) can be determined by whether the outcome exceeds the maximum count. As mentioned above, the maximum count is at least partially limited by the duration of the measurement window associated with the outcome.

[0074] Therefore, in this example, the disclosed embodiments have enabled the dynamic range of the measurement to be increased tenfold from 100,000 counts to 1,000,000 counts.

[0075] In further embodiments of this disclosure, the principle can be extended by providing more steps (e.g., more than just two different measurement windows and associated results).

[0076] By progressively using shorter measurement windows, such as 1 microsecond, 100 nanoseconds, and then 10 nanoseconds, increasingly higher levels of incident radiation can be detected. For example, a 10 nanosecond measurement window can be used for 1 / 100 of a second. Each 10 nanosecond SPAD measurement window has a 10 microsecond readout time. Therefore, each detected photon receives a weighting of 10 nanoseconds / 10 microseconds * 100 = 100,000. The number of readout cycles is (1 / 100 second) / 10 microseconds = 1000. Therefore, the maximum possible effective photon count would be 1000 * 100,000 = 10 8 .

[0077] The above examples illustrate how embodiments of the present invention can extend the dynamic range beyond the maximum radiation detection level limit that can be imposed by the "dead time" of the SPAD.

[0078] For example, a SPAD-based sensor architecture that includes a counter (theoretically of unlimited size) connected to each SPAD will still be limited by the maximum detectable radiation intensity level that takes for the SPAD to recover from triggering and be ready for the next detection. For example, if the dead time is 100 ns, then a given SPAD can only detect a maximum of 1 / 100 ns = 10e7 photons per second. However, the disclosed embodiments make it possible to apply measurement windows of less than 100 ns. In this way, the limitations imposed by the dead time can be exceeded, as described in the example above, where a 10 ns measurement window would increase the limit to 10e8 photons per second.

[0079] In one embodiment, for every doubling of the intensity of the incident radiation (e.g., for every doubling of the count), the duration of the measurement window can be reduced to one-quarter.

[0080] It should be understood that the above embodiments can also overcome the limitations imposed by the SPAD dead time setting. 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 circuit implemented, this recovery time can be in the range of tens of nanoseconds or longer. For example, for a dead time of 100 nanoseconds, the maximum theoretical photon count per SPAD would be 10. 7 Every second.

[0081] In an example with a SPAD dead time of 100 ns, the SPAD measurement window can be reduced to, for example, only 50 nanoseconds. Within this measurement window, the probability of triggering the SPAD remains very low until the optical density approaches one photon per 50 nanoseconds (after considering quantum efficiency and area utilization). Therefore, embodiments of this disclosure can effectively detect radiation at twice the limit set by the SPAD dead time.

[0082] In some embodiments, this principle can be extended to values ​​as high as those corresponding to the minimum controllable measurement window, such as 10 nanoseconds. That is, with a measurement window of 10 nanoseconds and a dead time of 100 nanoseconds, it may be possible to detect radiation values ​​that are 10 times higher than the limit set by the SPAD dead time.

[0083] Figure 2 An example measurement cycle of a radiation-sensitive device according to an embodiment of the present disclosure is described.

[0084] exist Figure 2 In this process, the first measurement cycle 205 begins at time T0 = 0 seconds. Each measurement cycle lasts for 1 second. Thus, the second measurement cycle 210 begins at T1 = 1 second, and so on.

[0085] Continuing with the example of the 100 SPAD array above, where the readout rate is 10 MHz and therefore the time to read the entire array is 10 microseconds, a measurement window covering the entire 10 microseconds is used in the first portions 215 and 220 of each measurement cycle 205, 210. The first portion 215 of the first measurement cycle 205 extends from T0 = 0 seconds to T... 0_INT = 0.9 seconds. Similarly, the first part 220 of the second measurement period 210 extends from T1 = 1 second to T... 1_INT = 1.9 seconds, and so on.

[0086] As described above, each photon detected in the first part 215, 220 of each measurement cycle 205, 210 is weighted by 1. To extrapolate this number to 1 second, it is multiplied by 1 / 0.9, since only 0.9 seconds are used per second. Therefore, the result of a maximum count of 100,000 is based on this measurement.

[0087] In the second part 225, 230 of each measurement cycle 205, 210, a measurement window covering only 1 microsecond is used. The second part 225 of the first measurement cycle 205 starts from T. 0_INT =0.9 seconds extends to T1 = 1 second. Similarly, the second part 230 of the second measurement period 210 extends from T... 1_INT =1.9 seconds extends to T2=2 seconds, and so on.

[0088] As described above, since the SPAD is active for only 1 / 10 of the total time in the second part 225, 230 of each measurement cycle 205, 210, each detected photon receives a 10-fold weighting. Furthermore, to extrapolate this from 0.1 seconds to 1 second, an additional factor of 10 is applied. Since the theoretically maximum count of 10,000 can be measured within this 0.1 second, the application of the weighting factor effectively translates it to 1,000,000 counts per SPAD per second.

[0089] In other words, compared to a portion of the measurement period 205, 210 (e.g., the first portion 215, 220) in which the SPAD array measures incident radiation with a relatively long measurement window, the SPAD array measures incident radiation with a relatively short measurement window in a smaller portion of the measurement period 205, 210 (e.g., the second portion 225, 230).

[0090] In some embodiments, the duration of the measurement window in each consecutive segment of the measurement cycle may be increased to four times or decreased to one-quarter for every doubling of the signal (e.g., an increase in the intensity of the incident radiation).

[0091] Figure 3 An apparatus 300 including a radiation-sensitive device 320 according to an embodiment of the present invention is depicted. In some exemplary embodiments, the apparatus 300 may be an apparatus for point-of-care (PoC) testing or electronic nose (E-nose) type applications or environmental radiation sensor applications.

[0092] The radiation-sensitive device 320 includes a plurality of SPADs 305. The plurality of SPADs 305 may be arranged as one or more arrays of SPADs 305.

[0093] The radiation-sensitive device 320 also includes a plurality of single-bit counters 310, such as latches. Each of the plurality of single-bit counters 310 is associated with a SPAD in a plurality of SPADs 305, as referenced above. Figure 1 As described. The SPAD305 and the associated single-bit counter 310 can be based on Figure 1 The SPAD-based sensor architecture 100 is arranged accordingly.

[0094] The radiation-sensitive device 320 also includes processing circuitry 315. In some embodiments, processing circuitry 315 may be configured to control a plurality of SPADs 305. For example, in some embodiments, processing circuitry 315 may be configured to control the quenching of SPADs 305 and / or the reset or activation of one or more SPADs 305. Processing circuitry 315 may also be configured to detect one or more faulty SPADs 305.

[0095] In some embodiments, the processing circuit 315 may be configured to read the single-bit counter 310. In some embodiments, the processing circuit 315 may also be configured to reset the single-bit counter 310 as needed. The processing circuit 315 may include at least one of the following: a CPU, a microcontroller, a state machine, combinational logic, etc.

[0096] In some embodiments, the processing circuit 315 may be configured to determine the intensity of incident radiation from the array of SPADs using a plurality of different measurement windows to provide a plurality of associated results, wherein the processing circuit 315 is configured to determine the intensity of the incident radiation based on one of the plurality of results, the selection of the result being determined by whether the result exceeds a maximum count, which is at least partially defined by the duration of the measurement window associated with the result.

[0097] In some embodiments, an aperture, lens, optical cover, grating, or one or more other optical devices may be disposed between the SPAD 305 and the radiation source. Such devices may, for example, be configured to focus and / or diffuse radiation incident on the SPAD 305. 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 the SPAD 305. In such embodiments, at least some of the SPADs 305 may withstand incident radiation of a lower intensity than the other SPADs of the radiation-sensitive device 320. By using such displaced apertures, in conjunction with any of the above-described techniques, the dynamic range of the radiation-sensitive device 320 can be further increased.

[0098] Figure 4A method for increasing the dynamic range of a radiation-sensitive device including an array of SPADs is described. The method includes a first step 410, which involves measuring the intensity of incident radiation from the array of SPADs using multiple different measurement windows to provide multiple correlated results.

[0099] The method includes a second step 420, which determines the intensity of the incident radiation based on one of a plurality of results, the selection of which result is determined by whether the result exceeds a maximum count, the maximum count being at least in part limited by the duration of a measurement window associated with the result.

[0100] 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 these 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 into any embodiment, either alone or in any suitable combination with any other feature disclosed or shown herein.

[0101] List of reference numerals

[0102] 100 SPAD-based sensor architectures

[0103] 105-0……99SPAD

[0104] 110-0……99 Single-bit counter

[0105] 115 Processing Circuit

[0106] 205 First Measurement Cycle

[0107] 210 Second Measurement Cycle

[0108] 215 Part One

[0109] 220 Part 1

[0110] 225 Part Two

[0111] 230 Part Two

[0112] 300 device

[0113] 305 SPAD

[0114] 310 Single-bit Counter

[0115] 315 Processing Circuit

[0116] 320 Radiation-sensitive equipment

[0117] 410 First Step 420 Second Step

Claims

1. A radiation-sensitive device (320), comprising: An array of single-photon avalanche diodes (SPADs) (10⁵-0…9⁹); as well as Circuit (115), configured to measure the intensity of incident radiation from the array of SPADs using multiple different measurement time windows to provide multiple correlated results, during which the SPADs are active. The circuit (115) is configured to determine the intensity of the incident radiation based on one of the plurality of results, the selection of the result being determined by the result not exceeding a maximum count, the maximum count being associated with the measurement time window and defined at least in part by the duration of the measurement time window associated with the result.

2. The radiation-sensitive device (320) according to claim 1, wherein the circuit (115) is configured to scale at least one result using a corresponding weighting factor, the magnitude of the weighting factor corresponding to the duration of the measurement time window associated with the result.

3. The radiation-sensitive device (320) according to claim 1 or 2, wherein the maximum count is defined by the duration of the measurement time window associated with the result and the readout rate of the SPAD (105-0...99).

4. The radiation-sensitive device (320) according to claim 1 or 2, wherein the duration of the measurement time window varies by a factor of 4 in each consecutive part of the measurement cycle.

5. The radiation-sensitive device (320) according to claim 1 or 2, wherein the circuitry is configured to configure the array (105-0...99) of the SPAD to measure the incident radiation within a relatively short measurement time window during a smaller portion of the measurement period, the smaller portion of the measurement period being smaller than a portion of the measurement period during which the array of the SPAD measures the incident radiation within a relatively long measurement time window.

6. The radiation-sensitive device (320) according to claim 1 or 2, wherein the duration of each measurement time window is programmable.

7. The radiation-sensitive device (320) according to claim 1 or 2, wherein the duration of each part of the measurement cycle is programmable, and the duration of the measurement time window is different in each part of the measurement cycle.

8. The radiation-sensitive device (320) according to claim 1 or 2, wherein each of the plurality of SPADs (105-0...99) has an associated single-bit counter (110-0...99) for recording photon impacts.

9. A method for increasing the dynamic range of a radiation-sensitive device (320) comprising an array of single-photon avalanche diodes (SPADs) (10⁵-0…9⁹), the method comprising: - Utilize multiple different measurement time windows to measure the intensity of incident radiation from the array of SPADs to provide multiple correlated results; - The intensity of the incident radiation is determined based on one of the plurality of results, the selection of the result being determined by whether the result exceeds a maximum count, the maximum count being at least in part limited by the duration of the measurement time window associated with the result.

10. The method of claim 9, further comprising the step of selecting and / or programming the duration of each of the plurality of measurement time windows.

11. The method of claim 9 or 10, wherein the step of measuring the intensity of incident radiation from the array of SPADs (105-0…99) using a plurality of different measurement time windows comprises using a relatively short measurement time window within a smaller portion of the measurement period, said smaller portion of the measurement period being smaller than a portion of the measurement period having a relatively long measurement time window.

12. The method of claim 9 or 10, further comprising the step of selecting and / or programming the duration of a portion of the measurement cycle associated with each measurement time window.

13. The use of a radiation-sensitive device (320) according to any one of claims 1 to 8 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 (320) according to any one of claims 1 to 8, 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 (320) according to any one of claims 1 to 8 in an environmental radiation sensing application.

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