Proximity detection device having frequency-modulated continuous-wave light source and array of single-photon avalanche diodes

Abstract

To provide a proximity detection device having a frequency-modulated continuous-wave light source and an array of single-photon avalanche diodes.SOLUTION: A proximity detection device includes: a frequency-modulated continuous-wave (FMCW) light source; an array of single-photon avalanche diodes (SPADs); a beam splitter configured to receive light emitted from the FMCW light source and to output a first split beam and a second split beam; a transmission light pipe configured to direct the first split beam toward a target; an optical combiner configured to receive a combination of the second split beam and a portion of the first split beam returned from the target and to direct the combined light toward the array of SPADs; a reception light pipe configured to direct the portion of the first split beam returned from the target toward the optical combiner; and an optical bridge element extending between the transmission light pipe and the reception light pipe and configured to propagate the second split beam from the beam splitter to the optical combiner.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The described embodiments relate generally to proximity sensors, and more particularly to single-photon avalanche diode (SPAD)-based proximity sensors. [Background technology]

[0002] Maximizing the user-facing display and touch input area provided by a consumer electronics device can enhance the aesthetics of the device and improve the user experience. Maximizing the user-facing display and touch input area, particularly on smaller consumer electronics devices (e.g., mobile phones (e.g., smartphones) or wearable devices), as well as on medium-sized consumer electronics devices (e.g., tablet computers) and larger consumer electronics devices (e.g., televisions), may require minimizing the non-display user-facing area. A problem, however, is that the non-display user-facing area may be used to provide a window through which user-facing sensors or illuminators interact with the user. User-facing sensors may include, for example, a front camera, depth imaging sensor, proximity sensor, ambient light sensor, fingerprint reader, etc. In some cases, the area provided for the user-facing display and touch input area can be maximized by moving the user-facing sensors and illuminators behind the display. However, this can sometimes degrade sensor and / or display performance.

[0003] In some cases, the size of the opening(s) through which the user-facing sensor or illuminator interacts with the user or device environment may be reduced to provide for minimal optical needs of the user-facing sensor or illuminator. This can sometimes be achieved by using optical fibers, fiber optic bundles, or light guides to guide light transmission and reception between a full-size sensor or illuminator module and an optical window that is much smaller than the size of the sensor or illuminator module.

[0004] Crosstalk (XT) is defined as the amount of unwanted signal received by the sensor receiver (RX) from internal optical paths that do not involve light redirection by external or intended targets. Reducing the amount of system- and module-level crosstalk, as well as its drift, without sacrificing near-field target signals is often one of the key design considerations for bistatic optical sensors. Excessive XT and XT drift can significantly degrade near-field object detection and affect far-field time-of-flight object detection and ranging performance. For some types of proximity sensors that may be installed under a device cover, possibly with an air gap between the proximity sensor and the device cover, variations in the size of the air gap and changes in the cover surface condition during use (e.g., dirt, scratches, application of a screen protector, etc.) can induce changes in XT and XT drift that adversely affect proximity sensor performance. For example, a heavily soiled screen protector on top of a device cover can increase XT by more than 100 times.

[0005] A common technique used to determine the distance to each point on a target (e.g., the distance to one or more objects within a field of view (FoV)) involves measuring the round-trip time-of-flight (ToF) of emitted electromagnetic radiation pulses (e.g., measuring the round-trip ToF of one or more photons in each of several electromagnetic radiation pulses, pixel by pixel). However, the accuracy of ToF measurements made by SPAD-based photon detectors can be compromised by various factors. For example, using a time-to-digital converter (TDC) or histogram memory with too few memory locations or too shallow a depth may result in too coarse a resolution or too much uncertainty (e.g., a sampling rate below the Nyquist frequency) for a desired application. However, TDCs and histogram memories that enable finer resolution or greater measurement certainty may be expensive in terms of area requirements, power consumption, manufacturing costs, etc. Summary of the Invention

[0006] The system, device, method, and apparatus embodiments described in this disclosure are directed to SPAD-based photon detectors, and more specifically, frequency modulated continuous wave (FMCW) SPAD-based proximity sensors and proximity sensing devices.

[0007] In a first aspect, the present disclosure describes a proximity sensing device. The proximity sensing device may include an FMCW light source, an array of SPADs, an optical splitter, a transmit light pipe, an optical combiner, a receive light pipe, and an optical bridge element. The optical splitter may be configured to receive light emitted by the FMCW light source and output a first split light and a second split light. The transmit light pipe may be configured to direct the first split light toward a target. The optical combiner may be configured to receive a combination of the second split light and a portion of the first split light returned from the target and direct it toward the array of SPADs. The receive light pipe may be configured to direct the portion of the first split light returned from the target toward the optical combiner. The optical bridge element may extend between the transmit light pipe and the receive light pipe and transmit the second split light from the optical splitter to the optical combiner.

[0008] In a second aspect, the present disclosure describes another proximity sensing device. The proximity sensing device can include an FMCW light source, an array of SPADs, an optical splitter, an optical combiner, a set of SPAD output pulse counters, and a SPAD output selection and routing network. The optical splitter can be configured to receive light emitted by the laser light source and output a first split light and a second split light. The optical combiner can be configured to receive and direct a combination of the second split light and a portion of the first split light returned from the target to the array of SPADs. The SPAD output selection and routing network can be operable to combine a set of SPAD outputs received from a subset of SPADs in the array of SPADs to the set of SPAD output pulse counters.

[0009] In a third aspect, the present disclosure describes another proximity sensing device. The proximity sensing device can include an FMCW light source, an array of SPADs, an optical splitter configured to receive light emitted by the laser light source and output a first split light and a second split light, an optical combiner configured to receive a combination of the second split light and a portion of the first split light returned from the target and direct it to the array of SPADs, and a set of one or more optical elements configured to direct the first split light to the target and the second split light to the optical combiner. The set of one or more optical elements, in combination with the optical combiner, can direct a coherent combination of the second split light and a portion of the first split light toward a subset of SPADs in the array of SPADs.

[0010] In addition to the aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following descriptions.

[0011] The disclosure will be readily understood from the following detailed description when taken in conjunction with the accompanying drawings, in which like reference numerals designate like structural elements and in which: [Brief explanation of the drawings]

[0012] [Figure 1] 1 illustrates an exemplary proximity sensor located under a protective cover.

[0013] [Figure 2A] 2 illustrates an exemplary embodiment of the proximity sensor shown in FIG. 1. [Figure 2B] 2 illustrates an exemplary embodiment of the proximity sensor shown in FIG. 1.

[0014] [Figure 3A] 2B illustrates an exemplary variation of the proximity sensor shown in FIG. 2A. [Figure 3B] 2B illustrates an exemplary variation of the proximity sensor shown in FIG. 2A.

[0015] [Figure 4]1 shows an electrical block diagram of the laser light source(s), array of SPADs, and other components of an exemplary proximity sensor.

[0016] [Figure 5A] 1 illustrates an exemplary implementation of an array of SPADs and associated readout (R / O) circuitry. [Figure 5B] 1 illustrates an exemplary implementation of an array of SPADs and associated readout (R / O) circuitry.

[0017] [Figure 6] 5C illustrates an alternative embodiment of the R / O circuit shown in FIG. 5B.

[0018] [Figure 7] 1 shows an example of how the circuits and proximity sensing devices described with reference to FIGS. 1 to 6 may operate.

[0019] [Figure 8] 1-6 illustrate exemplary transmission and reception of light by the circuits and / or proximity sensing devices described with reference to FIGS.

[0020] [Figure 9A] 1 illustrates an example of a device that may include a proximity sensor. [Figure 9B] 1 illustrates an example of a device that may include a proximity sensor.

[0021] [Figure 10] FIG. 1 illustrates a sample electrical block diagram of an electronic device including a proximity sensor, such as an FMCW SPAD-based proximity sensor.

[0022] The use of cross-hatching or shading in the accompanying figures is generally provided to clarify boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor absence of cross-hatching or shading is intended to convey or indicate any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristics, attributes, or properties with respect to any element shown in the accompanying figures.

[0023] Additionally, it will be understood that the proportions and dimensions (whether relative or absolute) of the various features and elements (and collections and groups thereof), as well as the boundaries, separations and relationships presented therebetween, are provided in the accompanying figures merely to facilitate understanding of the various embodiments described herein, and as such may not necessarily be presented or drawn to scale, and are not intended to imply any preference or requirement for the illustrated embodiment to the exclusion of the embodiment described with reference thereto. DETAILED DESCRIPTION OF THE INVENTION

[0024] Reference will now be made in detail to exemplary embodiments as illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit these embodiments to a single preferred embodiment. On the contrary, the following description is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the described embodiments and the appended claims.

[0025] Bistatic optical proximity sensors can have various challenges. For example, some bistatic optical proximity sensors experience high levels of XT, which in some cases can be from reflections from or between the surface of the device cover under which the sensor is mounted. XT can also result from dirt, scratches, the application of a screen protector, etc. As one example, for a device that has dirt on the cover on which optical proximity sensing occurs and needs to detect a target that returns a weak optical signal (e.g., a user's face or wrist with thick black hair positioned between the proximity sensor and the skin of the user's face or wrist), the XT returned from the dirt can obscure or bury the desired optical signal returned from the user's wrist. As another example, if a bistatic optical proximity sensor has too low timing resolution (e.g., in the case of a SPAD-based proximity sensor with limited histogram memory), it can be difficult to distinguish XT resulting from reflections from the device cover from dirt on the device cover and / or from a user's finger touching (or near) the device cover.

[0026] Described herein are proximity sensors (eg, proximity detection and ranging sensors) and proximity sensing devices that incorporate a SPAD-based digital FMCW sensing architecture and / or a multi-dimensional optical design.

[0027] Some embodiments of the described proximity sensors and proximity sensing devices provide cost-effective proximity sensing solutions or solutions that require a relatively small window or windows through a device cover or housing, and / or that can distinguish targets from XT more effectively than some currently available proximity sensor and proximity sensing solutions. The described SPAD-based digital FMCW sensing architecture can provide highly efficient, shot-noise-limited coherent detection performance at greater two-dimensional (2D) scalability than conventional analog FMCW architectures. The combination of freeform and wave-based optics can provide minimal device surface occupancy and good coherent mixing efficiency. The resulting high detection signal-to-noise ratio (SNR), high three-dimensional (3D) ranging resolution, and complementary 3D target velocity information can all be used to improve XT separation (i.e., separation of XT and desired optical signal or signals).

[0028] FMCW operation is enabled by mixing the optical signal emitted by the FMCW light source and returned from the target with a portion of the optical signal emitted by the FMCW light source and directed along the local oscillator (LO) path. Also mixed with the return and LO signals are XT and ambient light. In some embodiments, the LO path may be designed using wave optics (e.g., surface gratings, metasurfaces, etc.) formed on or in, or disposed adjacent to, the light pipe input or output face. In some embodiments, an optical splitter may be formed on the input face of the transmit light pipe and / or an optical combiner may be formed on the output face of the receive light pipe. Internal reflection and waveguiding within the flanges connecting the transmit and receive light pipes can be used to define the LO path. Alternatively, the LO path may be established using separate optical components (i.e., components not integrally formed with the transmit and receive light pipes).

[0029] Light received from the target and along the LO path may be coherently mixed and directed to an array of SPADs (e.g., a 2D array of SPADs). The coherently mixed light may be synchronized with the transmitter scan plan (e.g., a triangular intensity variation / frequency chirping scan plan) and read out per SPAD (e.g., per SPAD pixel) or per SPAD superpixel (e.g., per group of SPAD pixels), as determined by SNR, resolution, and latency needs. The signals read out per SPAD pixel or per SPAD superpixel may be sequentially processed in the frequency domain to extract instantaneous 2D range and velocity maps. The high ranging and velocity resolution that may be provided by each SPAD pixel, combined with the agile spatial / angular and temporal resolution, may provide high-dimensional data for good target / XT signal separation. The SPAD pixel or SPAD superpixel outputs may also be processed, in some cases, to determine the range and velocity to two or more targets (e.g., both near-field and far-field targets).

[0030] Compared to conventional direct ToF (dToF) sensors, the proximity sensors described herein can have a resolution that is one or more orders of magnitude higher (e.g., 1 mm resolution versus 20 millimeter (mm) resolution).

[0031] In contrast to proximity sensors that provide only distance measurements, the described SPAD-based digital FMCW sensing architecture can provide distance and angular resolution (which together provide a 3D measurement) and can also provide velocity (e.g., can provide a Doppler signature that can indicate whether a target is moving toward or away from the proximity sensor, or that can enable a processor to determine, based on fluctuations, for example, whether the target is human or inanimate). The described SPAD-based digital FMCW sensing architecture can also generate multiple frames of data, which provides another degree of freedom (e.g., time resolution).

[0032] These and other embodiments are described below with reference to Figures 1-10. However, those skilled in the art will readily appreciate that the detailed description provided herein with reference to these figures is for illustrative purposes only and should not be construed as limiting.

[0033] Directional terms, such as "top," "bottom," "upper," "lower," "front," "back," "over," "under," "above," "below," "left," "right," etc., may be used with reference to some orientations of components in some of the figures described below. Because components in various embodiments may be arranged in several different orientations, the directional terms are used for illustrative purposes only and are not necessarily limiting. The directional terms are intended to be interpreted broadly and, therefore, should not be interpreted to exclude components that are arranged in a different manner. Also, as used herein, the phrase "at least one" preceding a series of items, along with the terms "and" or "or" separating any of the items, modifies the list as a whole and not each member of the list. The phrase "at least one" does not require the selection of at least one of each listed item; rather, the phrase allows for the inclusion of at least one of any of the items, and / or at least one of any combination of the items, and / or at least one of each of the items. By way of example, the phrases "at least one of A, B, and C" or "at least one of A, B, or C" each refer to A only, B only, or C only, any combination of A, B, and C, and / or one or more of each of A, B, and C. Similarly, it can be understood that the order of elements presented for combined or separated lists provided herein should not be construed as limiting the disclosure to only the order provided.

[0034] FIG. 1 shows an exemplary proximity sensor 100 disposed under a protective cover 102 (e.g., a device cover that extends over a display and / or provides a touch input surface, or another type of cover (e.g., a structural housing member)). The proximity sensor 100 and protective cover 102 may be part of a proximity sensing device (e.g., the device shown in FIGS. 9A and 9B). In addition to being usable for proximity sensing, the proximity sensing device may perform other functions and, in some embodiments, may be a mobile phone, a computer, or a wearable device.

[0035] The proximity sensor 100 may include a frequency-modulated continuous wave (FMCW) light source 104, which may include a laser light source 106 (e.g., a vertical-cavity surface-emitting laser (VCSEL) or other type of laser, or another type of coherent or at least partially coherent light source) and associated control circuitry 108. The proximity sensor 100 may also include an array 110 of single-photon avalanche diodes (SPADs). The array 110 is preferably a two-dimensional (M×N) array, where M≧2 and N≧2, although in some cases the array 110 may be a one-dimensional (1×N) array, where N≧2. Alternatively, the array 110 may be replaced by a ring of SPADs, a radial line of SPADs, or another type of arrangement of multiple SPADs.

[0036] Both the laser source 106 and the array of SPADs 110 may be mounted to have a fixed spatial relationship with respect to one another. For example, the laser source 106 and the array of SPADs 110 may be implemented or formed on a substrate 112 (e.g., on a printed circuit board (PCB) and / or on the substrate of an application specific integrated circuit (ASIC) 130), attached to a device housing, and / or attached to a module housing (e.g., a metal or plastic container). In some embodiments, the array of SPADs 110 may be formed within the ASIC 130, and the laser source 106 may be attached to (e.g., stacked on) the ASIC 130.

[0037] The optical splitter 114 may be positioned to receive the light 116 emitted by the FMCW light source 104 and output a first split light 118 and a second split light 120. The first split light 118 may be directed towards a target 122, and the second split light 120 may be directed along a local oscillator (LO) path.

[0038] The optical combiner 124 may be positioned to receive and direct a combination of the second split light 120 (received from the LO path) and a portion 126 of the first split light returned from the target 122 toward the array of SPADs 110. Some or all of the light received by the optical combiner 124 may be coherently mixed (i.e., interfered).

[0039] The optical bridging element 128 can propagate the second split light 120 from the optical splitter 118 to the optical combiner 124. In some embodiments, the optical bridging element 128 may include an optical fiber or a light pipe. In some embodiments, the optical splitter 114 and / or the optical combiner 124 may be formed on or in the optical bridging element 128 (e.g., on one or more surfaces of the optical bridging element 128). In some embodiments, the protective cover 102 may be the optical bridging element 128. In some of these latter embodiments, the optical splitter 118 and / or the optical combiner 124 may be formed on a surface of the protective cover 102.

[0040] In some cases, a screen protector 132 may be applied to the protective cover 102. The screen protector 132 may be thinner, thicker, or about the same thickness as the protective cover 102. The screen protector 132 may be made of glass, plastic, or another material and may include a layer of adhesive that allows the screen protector 132 to adhere to the protective cover 102. In some cases, dirt 134 or other deposits of material (e.g., oil, dust, organic matter, etc.) may form on or adhere to the screen protector 132 (or to the protective cover 102 if the screen protector 132 is not present). In some cases (not shown), the protective cover 102 and / or the screen protector 132 may have cracks, scratches, or chips therein. All of these features (e.g., screen protector 132, dirt 134 or other deposits of material, cracks, scratches, or chips) can reflect, refract, or direct light in a manner that introduces XT between FMCW light source 104 and array of SPADs 110. It is useful to mitigate or eliminate the effect of such XT on array of SPADs 110 and / or measurements determined from its output (i.e., from the SPAD output).

[0041] 2A and 2B illustrate an exemplary embodiment of the proximity sensor 100 shown in FIG. 1. The embodiment includes a transmit light pipe 200 and a receive light pipe 202. The transmit light pipe 200 may be configured to direct the first split light 118 toward the target 122. The receive light pipe 202 may be configured to direct a portion 126 of the first split light returned from the target 122 to the light combiner 124. An optical bridging element 128 may be disposed between the transmit light pipe 200 and the receive light pipe 202 and extend between the transmit light pipe 200 and the receive light pipe 202.

[0042] 2A , optical bridge element 128 connects transmit light pipe 200 and receive light pipe 202. In some of these embodiments, optical splitter 114 may be formed on the receive end 204 of transmit light pipe 200 and / or optical combiner 124 may be formed on the emitter end 208 of receive light pipe 202 (however, in other embodiments, optical splitter 114 and / or optical combiner 124 may be implemented separately from transmit light pipe 200 or receive light pipe 202). In some embodiments, one or both of optical splitter 114 and optical combiner 124 may be formed by a surface grating or a metasurface.

[0043] 2A , the optical bridge element 128 connects to the send light pipe 200 closer to the receiving end 204 of the send light pipe 200 than to the receiving end 206 of the send light pipe 200, and connects to the receive light pipe 202 closer to the light emitting end 208 of the receive light pipe 202 than to the receiving end 210 of the receive light pipe 202. In an alternative embodiment, the optical bridge element 128 can connect to the send light pipe 200 closer to the light emitting end 206 of the send light pipe 200 than to the receiving end 204 of the send light pipe 200, and connect to the receive light pipe 202 closer to the receiving end 210 of the receive light pipe 202 than to the light emitting end 208 of the receive light pipe 202. In other embodiments, the optical bridge element 128 may connect to the midpoint of the transmit light pipe 200 and the receive light pipe 202, or the optical bridge element 128 may connect to each of the transmit light pipe 202 and the receive light pipe 202 at different relative locations.

[0044] 2B, the optical bridging element 128 may include at least one of a surface grating or a metasurface. In some cases, the optical bridging element 128 may be etched into, or formed on or in, the flange connecting the transmit light pipe 200 and the receive light pipe 202.

[0045] In some embodiments, the transmit light pipe 200, the receive light pipe 202, and the optical bridging element 128 may be provided by a set of one or more optical elements. In some embodiments, the set of one or more optical elements may consist of a monolithic optical element (i.e., a single, integral structure that defines all of the optical elements shown). In some embodiments, the monolithic optical element may further define the optical splitter 114 and the optical combiner 124.

[0046] 3A and 3B illustrate example variations of the proximity sensor 100 shown in FIG. 2A, although the variations shown may be made to any of the embodiments described herein.

[0047] 3A and 3B, the laser light source 106 is a first laser light source 106, and the FMCW light source 104 further includes one or more additional laser light sources (e.g., a second laser light source 300). Each of the first laser light source 106 and the second laser light source 300 may be positioned to emit light toward the optical splitter 114. In this embodiment, the controller 302 may be configured to address and operate the first laser light source 106 and the second laser light source 300 separately.

[0048] Depending on the position and characteristics of the target (e.g., size, material, surface quality, etc.), one or more of the laser sources may provide a better return signal and / or a return signal that mixes better with the second split light 120. For example, in some cases, gating the first laser source 106 on while the second laser source 300 is off may provide better mixing of the second split light 120 with the portion 126 of the first split light returned from the target 122 while conserving power. In other cases, gating the second laser source 300 on while the first laser source 106 is off may provide better mixing of the second split light 120 with the portion 126 of the first split light returned from the target 122 while conserving power. Alternatively, both laser sources 106, 300 may be gated on or off simultaneously.

[0049] In some embodiments, the first laser light source 106 and the second laser light source 300 can emit light of the same wavelength. Alternatively, the first laser light source 106 and the second laser light source 300 can emit light of different wavelengths.

[0050] In addition to, or instead of, the first laser light source 106 and the second laser light source 300, one or more configurable optical elements (e.g., optical elements that can be moved or electronically reconfigured) may be used to direct the light emitted by the laser light sources in different directions. Each of the one or more laser light sources may also be configured to have a different polarization, or one or more optical elements may be used to statically or dynamically change the polarization of the emitted light.

[0051] 4 shows an electrical block diagram 400 of laser source(s) 402, an array of SPADs 404, and other components of an exemplary proximity sensor (e.g., one of the proximity sensors described herein). In some cases, the laser source 402 and the array of SPADs 404 can be configured as described with reference to any of FIGS. 1-3B. By way of example, the other components may include one or more of a transmit driver and laser compliance circuit 406, a high voltage generation circuit 408 for the array of SPADs 404, peripheral and readout (R / O) circuitry 410, and / or processing circuitry 412 (e.g., a digital signal processor (DSP) for calculating target range or distance to the target).

[0052] 5A and 5B show an example implementation of an array of SPADs 500 and associated R / O circuitry 502. In some cases, the array 500 of SPADs and R / O circuitry 502 may be the array of SPADs and R / O circuitry described with reference to FIG.

[0053] 5A as an 8×8 array of SPADs. In other examples, the array of SPADs 500 may be any M×N array of SPADs, where M≧1 and N≧2. The R / O circuitry 502 may include a set of SPAD output pulse counters (CNTs) 504 and a SPAD output selection and routing network 506. The SPAD output selection and routing network 506 may be operable to couple a set of SPAD outputs received from a subset of the SPADs in the array of SPADs 500 to the set of SPAD output pulse counters 504.

[0054] FIG. 5A illustrates exemplary incidences of light returned from a target (e.g., light returned from a target in any of FIGS. 1-3B as spot 508-1) and light received via the LO path (e.g., second split light generated by an optical splitter in FIGS. 1-3B as spot 510). As shown, spots 508-1, 510 may overlap, the overlap representing mixing (interference) of light received along different paths (i.e., from the target and from the LO path). In some embodiments, there may be two or more spots of light returned from two or more targets, such as a first spot 508-1 representing light returned from a near-field target and a second spot 508-2 representing light returned from a far-field target. A portion of each of near-field spot 508-1 and far-field spot 508-2 may mix with LO spot 510.

[0055] The SPAD output and routing network 506 can be configured in various ways depending on the resource budget (available implementation space, cost, timing tolerances, etc.). In FIG. 5B, the SPAD output selection and routing network 506 is shown to include a set of M power shaping (PS) circuits 512, each receiving the SPAD outputs 514 of N SPAD pixels 516 (i.e., in other embodiments, each PS circuit may receive the SPAD outputs of more or fewer SPAD pixels 516, but each SPAD output may be output in a row of N SPAD pixels 516). Each PS circuit can provide N shaped SPAD outputs to a regrouping circuit 518 (e.g., a switching circuit). Alternatively, the SPAD outputs 514 can be provided directly to the regrouping circuit 518 (i.e., without first being shaped by a set of PS circuits 512).

[0056] The regrouping circuit 518 can be programmed to route different combinations of the SPAD outputs 514 to different logic gates 520 (e.g., different OR gates). Each OR gate can generate a pulse each time one of the SPAD outputs input to the OR gate carries a pulse (i.e., a pulse indicating that the individual SPAD has been triggered by received light). Each counter in the set of SPAD output pulse counters 504 can increment its count each time an individual OR gate indicates that a SPAD output pulse has been received. At the end of each period in the series of periods, the SPAD output pulse counter can output its count to an individual multiplexer in the set of multiplexers 522. The multiplexers in the set of multiplexers 522 can be controlled to output each count from the set of SPAD output pulse counters 504 to one of several pulse train memories. By way of example, two pulse train memories (i.e., pulse train memory 1 524-1 and pulse train memory 2 524-2) are shown, although any number of one or more pulse train memories may be provided. If only one pulse train memory is provided, each counter in the set of SPAD output pulse counters 504 may provide its output directly to a single pulse train memory.

[0057] 5A, there may be a subset 526 of SPADs that receive a combination of light returned from the target (i.e., spot 508-1) and light received via the LO path (i.e., spot 510). The outputs of the SPADs 516 included in the subset 526 of SPADs are grouped together by a regrouping circuit 518 and provided to one or more of the logic gates 520. The SPAD output pulse counters 504 associated with these logic gates 520 may then be routed to the same pulse train memory (524-1 or 524-2) by providing an appropriate output select signal to a set of multiplexers 522. In some cases, the outputs of different subsets of SPADs 516 (e.g., the outputs of the SPADs incident on spots 508-2 and 510) may be routed to different pulse train memories 524-1 or 524-2. For example, output pulses from a SPAD receiving return light from a near-field target or range may be combined with light received from the LO path and routed to a first subset of one or more SPAD output pulse counters 504 and a first pulse train memory 524-1, and output pulses from a SPAD receiving return light from a far-field target or range may be combined with light received from the LO path and routed to a second subset of one or more SPAD output pulse counters 504 and a second pulse train memory 524-2.

[0058] In some embodiments, the SPAD output selection and routing network 506 (or the R / O circuitry 502 generally) may be programmed prior to end-use deployment of the proximity sensing device. For example, if the proximity sensing device is to be included in a particular type of device under a cover (or under a cover and potentially a screen protector), this may be determined in a laboratory or manufacturing environment where each spot 508-1, 508-1, and / or 510 is incident on the array of SPADs 500, a subset of SPADs (e.g., subset of SPADs 526) may be defined, and the SPAD output selection and routing network 506 may be statically or semi-statically programmed. In some embodiments, targets that the proximity sensing device, including the array of SPADs 500 and associated R / O circuitry 502, is configured to detect may be estimated to be within a particular range (e.g., the near-field range of the proximity sensing device), and the SPAD output selection and routing network 506 (or the R / O circuitry 502 generally) may be programmed to detect such targets. In some embodiments, the SPAD output selection and routing network 506 (or the R / O circuitry 502 in general) can be programmed to detect two or more targets (e.g., a near-field target and a far-field target) within each particular range (e.g., a particular near-field range and a particular far-field range of the proximity sensing device).

[0059] In some embodiments, the SPAD output selection and routing network 506 (or the R / O circuitry 502 generally) may be associated with a controller 528, which may be configured to periodically obtain data from the array of SPADs 500 and program the SPAD output selection and routing network 506 (e.g., in field programming) during end-use deployment of the proximity sensor.

[0060] The controller 528 (or processor) may also receive a count of the SPAD output pulses (e.g., from pulse train memory 524-1 or pulse train memory 524-2) and use it to separate the optical signal returned from the near-field target from crosstalk.

[0061] FIG. 6 shows an alternative embodiment of the R / O circuit 502 shown in FIG. 6. In the embodiment of FIG. 6, an enable circuit 600 is disposed between the set of logic gates 520 and the set of SPAD output pulse counters 504. The enable circuit 600 is operable to connect the SPAD outputs in the set of SPAD outputs 514 to the set of SPAD output pulse counters 504 or to disconnect the SPAD outputs in the set of SPAD outputs 514 from the set of SPAD output pulse counters 504. By way of example, the enable circuit 600 may include a set of D flip-flops, each having a D input connected to a count enable signal line (CNT_EN), each having a clock input connected to a respective output of a logic gate in the set of logic gates 520, and each having an output (Q output) connected to an input of a respective multiplexer in the set of multiplexers 522.

[0062] FIG. 7 shows an example of how the circuit and proximity sensing device described with reference to FIGS. 1-6 may operate. At time 700, a ramp of the operating frequency of the FMCW light source may begin, and the operating frequency may be swept across a range of frequencies (e.g., from low to high) between times 700 and 702. At time 704, a portion of the light emitted by the FMCW light source and returned from the target may first be received at an array of SPADs (e.g., at the array of SPADs shown in FIG. 5A). The time difference between times 700 and 704 represents the time of flight (ToF) of the light as it travels from the FMCW light source to the target and then to the array of SPADs. The ToF for the light to travel from the FMCW light source to the array of SPADs is negligible and may or may not be considered.

[0063] As the operating frequency of the FMCW light source is swept, various SPADs in the SPAD array may be triggered by photons returned from the target, photons received via the LO path, or a combination of photons received via the LO path and photons returned from the target. Figure 7 shows triggering of the first SPAD (SPAD1 output), the second SPAD (SPAD2 output), and the Xth SPAD (SPADX output). The triggering of the various SPADs, indicated by SPAD output pulses, may be sampled according to a sampling time (or sample clock) that generates a series of sample periods. During each sampling time, the number of SPAD output pulses contained in the SPAD output received by one of the logic gates (e.g., OR gates) described with reference to Figure 5A may be counted by a separate SPAD output pulse counter. The counts (CNT) of SPAD output pulses generated by the SPAD output pulse counter over a series of sample periods may be stored in a pulse train memory (PULSE TRAIN MEM). The contents of the pulse train memory may be subjected to a fast Fourier transform (FFT) to determine the beat frequency (f beat ) can be output to (or read by) a processor which finds a peak representing the beat frequency. The beat frequency can be used in accordance with known techniques to determine the distance to the target. In some cases, there may be more than one beat frequency, indicating that light is being returned from more than one target (e.g., a near-field target and a far-field target).

[0064] FIG. 8 illustrates exemplary transmission and reception of light by the circuitry and / or proximity sensing device described with reference to FIGS. 1-6. Times 700, 702, and 704 are the same times introduced in FIG. 7. At time 700, a ramp of the operating frequency of the FMCW light source begins, and coherent light (or at least partially coherent light) having varying frequencies is emitted by the FMCW light source into the field of view. Light is emitted from time 700 (start of frequency ramp) to time 702 (end of frequency ramp). In alternative embodiments, the emitted light may be chirped with chirps having different frequencies, or the light may be emitted according to other predetermined patterns or characteristics.

[0065] At time 704, the array of SPADs can begin to receive some of the light emitted by the FMCW light source and returned from the target. The time difference between times 700 and 704 represents the ToF as the light travels from the FMCW light source to the target and then to the array of SPADs. The ToF for the light traveling from the FMCW light source to the array of SPADs is negligible and may or may not be considered.

[0066] Between times 700 and 704, the array of SPADs can receive light along the LO path as well as stray light (e.g., ambient light and light reflected from surfaces within the device, the surface of a screen protector, dirt, etc.). All of this light can be considered noise. Similarly, light received after the frequency ramp has ended (i.e., after time 702) can be considered noise. The enable circuit described with reference to FIG. 6 can be used to gate out this noise, so that SPAD output pulses are not counted and counts are not stored in the pulse train memory between times 700 and 704 or after time 702. Alternatively, the enable signal (CNT_EN) provided to the enable circuit may gate the SPAD output pulse counter ON after time 700 but shortly before time 704, and gate the SPAD output pulse counter OFF at or after time 702.

[0067] The period between time 700 and time 702 is the ungated signal integration time (T 信号 ), and the period between time 700 and time 800 may be considered as the stray accumulation time (T 漂遊 ) and T 漂遊 is T 信号 The attention accumulation time is T 信号 -T 漂遊 It can be expressed as:

[0068] 9A and 9B show an example of a device 900 that may include a proximity sensor (thereby making the device 900 a proximity-sensing device, although the device 900 may have other purposes). The dimensions and form factor of the device, including the ratio of the device's long side length to its short side length, suggest that the device 900 is a mobile phone (e.g., a smartphone). However, the dimensions and form factor of the device are selected arbitrarily, and the device 900 may alternatively be any portable electronic device, including, for example, a tablet computer, a portable computer, a portable music player, a wearable device (e.g., an electronic watch, a health monitoring device, a fitness tracking device, a headset, or glasses), an augmented reality (AR) device, a virtual reality (VR) device, a mixed reality (MR) device, a gaming device, a handheld terminal, a digital single-lens reflex (DSLR) camera, a video camera, a vehicle navigation system, a robotic navigation system, or other portable or mobile device. The device 900 may also be a device that is semi-permanently located (or installed) in a single location. 9A shows a front isometric view of device 900, and FIG. 9B shows a back isometric view of device 900. Device 900 may include a housing 902 that at least partially encloses a display 904. Housing 902 may include or support a front cover 906 or a back cover 908. Front cover 906 may be disposed over display 904 and may provide a window through which display 904 can be viewed. In some embodiments, display 904 may be connected to (or adjacent to) housing 902 and / or front cover 906. In alternative embodiments of device 900, display 904 may not be included and / or housing 902 may have an alternative configuration.

[0069] Display 904 may include one or more light-emitting elements and may in some cases be a light-emitting diode (LED) display, an organic LED (OLED) display, a liquid crystal display (LCD), an electroluminescent (EL) display, or another type of display. In some embodiments, display 904 may include or be associated with one or more touch and / or force sensors configured to detect touch and / or force applied to the surface of front cover 906.

[0070] The various components of the housing 902 may be formed from the same or different materials. For example, the sidewall 918 of the housing 902 may be formed using one or more metals (e.g., stainless steel), polymers (e.g., plastic), ceramics, or composite materials (e.g., carbon fiber). In some cases, the sidewall 918 may be a multi-segment sidewall that includes a set of antennas. The antennas may form structural components of the sidewall 918. The antennas may be structurally coupled (to each other or other components) and electrically isolated (from each other or other components) by one or more non-conductive segments of the sidewall 918. The front cover 906 may be formed using, for example, one or more of glass, crystal (e.g., sapphire), or a transparent polymer (e.g., plastic) that allows a user to view the display 904 through the front cover 906. In some cases, a portion of the front cover 906 (e.g., the periphery of the front cover 906) may be coated with an opaque ink to hide the components contained within the housing 902. The back cover 908 may be formed using the same material(s) used to form the sidewalls 918 or the front cover 906. In some cases, the back cover 908 may be part of a monolithic element that also forms the sidewalls 918 (or the portions of the sidewalls 918 that are conductive or non-conductive, if the sidewalls 918 are multi-segment sidewalls). In still other embodiments, all of the external components of the housing 902 may be formed from a transparent material, and the components within the device 900 may or may not be obscured by opaque inks or structures within the housing 902.

[0071] The front cover 906 may be attached to the side wall 918 to cover an opening defined by the side wall 918 (i.e., an opening to an interior volume where various electronic components of the device 900 may be disposed, including the display 904). The front cover 906 may be attached to the side wall 918 using fasteners, adhesives, seals, gaskets, or other components.

[0072] A display stack or device stack (hereinafter referred to as "stack") including display 904 may be attached to (or adjacent to) the interior surface of front cover 906 and extend into the interior volume of device 900. In some cases, the stack may include touch sensors (e.g., a grid of capacitive, resistive, strain-based, ultrasonic, or other types of touch-sensing elements) or other layers of optical, mechanical, electrical, or other types of components. In some cases, the touch sensors (or part of a touch sensor system) may be configured to detect touches applied to the exterior surface of front cover 906 (e.g., the display surface of device 900).

[0073] In some cases, a force sensor (or part of a force sensor system) may be located within the interior volume above, below, and / or to the side of the display 904 (and possibly within the device stack). The force sensor (or force sensor system) may be triggered in response to the touch sensor detecting one or more touches on the front cover 906 (or one or more locations of touches or locations on the front cover 906) and may determine the amount of force associated with each touch or the amount of force associated with the collection of touches as a whole. In some embodiments, the force sensor (or force sensor system) can be used to determine the location of a touch or the location of a touch combined with the amount of force of the touch. In these latter embodiments, the device 900 may not include a separate touch sensor.

[0074] 9A , device 900 may include various other components. For example, the front surface of device 900 may include one or more forward-facing cameras 910 (including one or more 3D image sensors or depth sensors), a speaker 912, a microphone, or other components 914 configured to send or receive signals to or from device 900 (e.g., audio, imaging, and / or sensing components (e.g., a proximity sensor such as one of the proximity sensors described herein)). In some cases, front-facing camera 910 may be configured to operate as a biometric or facial recognition sensor, alone or in combination with other sensors. In some embodiments, a flash or electromagnetic radiation source (e.g., a visible or IR light source) may be positioned near the front-facing camera. In some cases, front-facing camera 910 may be positioned behind display 904 and receive electromagnetic radiation (e.g., light) through display 904. In some cases, proximity or depth sensors may be used to determine the distance to the user or generate a depth map of the user's face, or to determine the distance or proximity to an object or generate a depth map of the object (or of objects in the FoV that include the object). Device 900 may also include various input devices, including mechanical or virtual buttons 916, which may be accessible from the front (or display surface) of device 900.

[0075] The device 900 may also include buttons or other input devices disposed along the sidewalls 918 and / or back of the device 900. For example, a volume button or a multi-purpose button 920 may be disposed along the sidewalls 918 and, in some cases, may extend through an opening in the sidewalls 918. The sidewalls 918 may include one or more ports 922 that allow air to enter or exit the device 900 but not liquids. In some embodiments, one or more sensors may be disposed in or near the port(s) 922. For example, an ambient pressure sensor, an ambient temperature sensor, an internal / external differential pressure sensor, a gas sensor, a particulate matter concentration sensor, or an air quality sensor may be disposed in or near the port(s) 922.

[0076] In some embodiments, the back of device 900 may include a rear-facing camera 924 that includes one or more 3D image or depth sensors (see FIG. 9B). A flash or electromagnetic radiation source 926 (e.g., a visible or IR light source) may also be located on the back of device 900 (e.g., near the rear-facing camera). In some cases, the back of device 900 may include multiple rear-facing cameras.

[0077] FIG. 10 shows an example electrical block diagram of an electronic device 1000 including a proximity sensor, such as an FMCW SPAD-based proximity sensor, constructed or configured according to the principles described with reference to any of FIGS. 1-9B or elsewhere herein. The electronic device 1000 may take the form of a handheld or portable device (e.g., a smartphone, tablet computer, or electronic watch), a wearable device, a computing device, a vehicle navigation system, or the like. The electronic device 1000 may include an optional display 1002 (e.g., a light-emitting display), a processor 1004, a power supply 1006, a memory 1008 or storage device, a sensor system 1010, or optional input / output (I / O) mechanisms 1012 (e.g., input / output devices and / or input / output ports). The processor 1004 may control some or all of the operation of the electronic device 1000. The processor 1004 may communicate, directly or indirectly, with substantially all components of the electronic device 1000. For example, a system bus or other communication mechanism 1014 may provide communication between the processor 1004 , the power supply 1006 , the memory 1008 , the sensor system 1010 , and / or the input / output mechanism 1012 .

[0078] The processor 1004 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processor 1004 may be a microprocessor, a central processing unit (CPU), an ASIC, a DSP, a controller, or any combination of such devices. The term "processor" as used herein is intended to encompass a single processor or processing unit, multiple processors, multiple processing units, or another suitably configured one or more computing elements.

[0079] It should be noted that in some embodiments, components of electronic device 1000 may be controlled by multiple processors. For example, select components of electronic device 1000 may be controlled by a first processor, and other components of electronic device 1000 may be controlled by a second processor, where the first and second processors may or may not communicate with each other.

[0080] The power source 1006 may be implemented by any device capable of providing energy to the electronic device 1000. For example, the power source 1006 may include one or more disposable or rechargeable batteries. Additionally or alternatively, the power source 1006 may include a power connector or power cord that connects the electronic device 1000 to another power source, such as a wall outlet.

[0081] The memory 1008 can store electronic data that can be used by the electronic device 1000. For example, the memory 1008 may store electronic data or content, such as audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, maps, or focus settings. The memory 1008 can be configured as any type of memory. By way of example only, the memory 1008 may be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage elements, or a combination of such devices.

[0082] The electronic device 1000 may also include one or more sensors that define a sensor system 1010. The sensors may be located virtually anywhere on the electronic device 1000. The sensor(s) may be configured to sense virtually any type of characteristic, such as, but not limited to, touch, force, pressure, electromagnetic radiation (e.g., light), heat, motion, relative movement, biometric data, distance, etc. For example, the sensor system 1010 may include touch sensors, force sensors, thermal sensors, position sensors, light or optical sensors, accelerometers, pressure sensors (e.g., pressure transducers), gyroscopes, magnetometers, health monitoring sensors, image sensors, proximity sensors, etc. Additionally, the one or more sensors may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

[0083] The I / O mechanism 1012 may send and / or receive data from a user or another electronic device. The I / O device may include a touch-sensitive input surface such as a display, a trackpad, one or more buttons (e.g., a graphical user interface "home" button or one of the buttons described herein), one or more cameras (including one or more 2D or 3D image sensors (e.g., one or more SPAD-based photon detectors)), one or more microphones or speakers, one or more ports such as a microphone port, and / or a keyboard. Additionally or alternatively, the I / O device or port may transmit electronic signals over a communication network, such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet connections. The I / O mechanism 1012 may also provide feedback (e.g., tactile output) to the user.

[0084] The foregoing description, for purposes of explanation, uses specific terminology to provide a thorough understanding of the described embodiments. However, it will be apparent to those skilled in the art after reading this description that specific details are not required to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to those skilled in the art after reading this description that many modifications and variations are possible in light of the above teachings.

[0085] As mentioned above, one aspect of the present technology may be the collection and use of data available from a variety of sources. The present disclosure contemplates that, in some cases, this collected data may include personal information data (e.g., biometric information, position information, location information, or contextual information) that uniquely identifies a particular person or that may be used to identify, locate, contact, or diagnose a particular person. Such personal information data may include demographic data, location-based data, telephone numbers, email addresses, home addresses, data or records regarding a user's health or fitness level (e.g., vital sign measurements, medication information, exercise information), date of birth, or any other identifying or personal information.

[0086] This disclosure recognizes that the use of such personal information data in the present technology can be for the benefit of the user. For example, the personal information data can be used to activate or deactivate various features of the user's device or to collect performance metrics for the user's device or the user. Additionally, other uses of personal information data that benefit the user are contemplated by this disclosure. For example, health and fitness data can be used to provide insight into the user's overall wellness or can be used as proactive feedback to individuals using the technology in pursuit of wellness goals.

[0087] This disclosure contemplates that entities involved in the collection, analysis, disclosure, transmission, storage, or other use of such personal information data will adhere to robust privacy policies and / or privacy practices. Specifically, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining the strict confidentiality of personal information data. Such policies should be easily accessible to users and should be updated as data collection and / or use changes. Personal information from users should be collected for the entity's lawful and legitimate use and should not be shared or sold except for those lawful uses. Furthermore, such collection / sharing should be carried out only after the user's informed consent is obtained. Furthermore, such entities should consider taking all necessary measures to protect and secure access to such personal information data and to ensure that others with access to the personal information data adhere to their privacy policies and procedures. Furthermore, such entities may be able to undergo third-party assessments to demonstrate their adherence to widely accepted privacy policies and practices. Furthermore, policies and practices should be tailored to the specific types of personal data collected and / or accessed and should comply with applicable laws and standards, including jurisdiction-specific considerations. For example, in the United States (US), the collection of or access to certain health data may be governed by federal and / or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA), while health data in other countries may be subject to other regulations and policies and should be addressed accordingly. Therefore, different privacy practices should be maintained in each country with respect to different types of personal data.

[0088] Notwithstanding the foregoing, the present disclosure also contemplates embodiments in which a user may selectively prevent use of or access to personal information data. That is, the present disclosure contemplates that hardware and / or software elements may be provided to prevent or block access to such personal information data. For example, in the case of an advertising delivery service, the technology may be configured to allow a user to “opt in” or “opt out” of participating in the collection of personal information data during registration for the service or at any time thereafter. In another example, a user may choose not to provide mood-related data for a targeted content delivery service. In yet another example, a user may choose to limit the period for which mood-related data is maintained or to prohibit the development of a baseline mood profile entirely. In addition to providing “opt-in” and “opt-out” options, the present disclosure contemplates providing notice regarding the access or use of personal information. For example, a user may be notified upon downloading an app that will access the user's personal information data, and then again immediately before the app accesses the user's personal information data.

[0089] Furthermore, it is the intent of this disclosure that personal information data should be managed and processed in a manner that minimizes the risk of unintentional or unauthorized access or use. Risk can be minimized by limiting data collection and deleting data when it is no longer needed. Additionally, where applicable in certain health-related applications, data anonymization can be used to protect user privacy. Anonymization may be facilitated, where appropriate, by removing certain identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data at a city level rather than an address level), controlling how data is stored (e.g., aggregating data across users), and / or other methods.

[0090] Thus, while this disclosure broadly encompasses the use of personal information data to implement one or more various disclosed embodiments, this disclosure also contemplates that the various embodiments may be implemented without requiring access to such personal information data. That is, various embodiments of the present technology are not rendered inoperable by the absence of all or part of such personal information data. For example, content may be selected and delivered to a user by inferring preferences based only on a minimal amount of non-personal information or personal information, such as content requested by devices associated with the user, other non-personal information available on content delivery services, or publicly available information.

Claims

1. A proximity sensing device, comprising: a frequency modulated continuous wave (FMCW) light source; an array of single photon avalanche diodes (SPADs); an optical splitter arranged to receive the light emitted by the FMCW light source and output a first split light and a second split light; a delivery light pipe configured to direct the first split light toward a target; an optical combiner positioned to receive and direct a combination of the second split light and a portion of the first split light returned from the target to the array of SPADs; a receiving light pipe configured to direct the portion of the first split light returned from the target toward the light combiner; an optical bridge element extending between the transmit light pipe and the receive light pipe and transmitting the second split light from the optical splitter to the optical combiner.

2. The proximity sensing device of claim 1 , wherein the light bridging element comprises a light pipe.

3. the light pipe connects to the transmit light pipe closer to the light receiving end of the transmit light pipe than to the light emitting end of the transmit light pipe; the light pipe connects to the receiving light pipe closer to the light emitting end of the receiving light pipe than to the light receiving end of the receiving light pipe; The proximity sensing device of claim 2 .

4. the light pipe connects to the transmit light pipe closer to the light emitting end of the transmit light pipe than to the light receiving end of the transmit light pipe; the light pipe connects to the receiving light pipe closer to the receiving end of the receiving light pipe than to the light emitting end of the receiving light pipe; The proximity sensing device of claim 2 .

5. the optical splitter is formed on the receiving end of the transmitting light pipe; the optical combiner is formed on the light-emitting end of the receiving light pipe; The proximity sensing device of claim 2 .

6. The proximity sensing device of claim 1 , wherein the optical bridging element comprises at least one of a surface grating or a metasurface.

7. the FMCW light source includes a first laser light source and a second laser light source; the first laser light source and the second laser light source are each arranged to emit light toward the optical splitter; The proximity sensing device of claim 1 .

8. The proximity sensing device of claim 7 , further comprising a controller configured to separately address and operate the first laser light source and the second laser light source.

9. 10. The proximity sensing device of claim 1, further comprising: a controller configured to receive a count of SPAD output pulses generated by the array of SPADs and to separate optical signals returned from near-field targets from crosstalk.

10. A proximity sensing device, comprising: a frequency modulated continuous wave (FMCW) light source; an array of single photon avalanche diodes (SPADs); an optical splitter arranged to receive the light emitted by the FMCW light source and output a first split light and a second split light; an optical combiner positioned to receive and direct a combination of the second split light and a portion of the first split light returned from a target to the array of SPADs; a set of SPAD output pulse counters; a SPAD output selection and routing network operable to couple a set of SPAD outputs received from a subset of SPADs in the array of SPADs to the set of SPAD output pulse counters.

11. The proximity sensing device of claim 10 , wherein the SPAD output selection and routing network is programmed prior to end-use deployment of the proximity sensing device.

12. 11. The proximity sensing device of claim 10, further comprising a controller configured to periodically obtain data from the array of SPADs and program the SPAD output selection and routing network during end-use deployment of the proximity sensing device.

13. The proximity sensing device of claim 10 , wherein the SPADs in the subset of SPADs include a SPAD that receives both the second split light and the portion of the first split light returned from the target.

14. The proximity sensing device of claim 10 , wherein the target is presumed to be within a near-field range of the proximity sensing device.

15. the target is a near-field target, the portion of the first split light returned from the target is a first portion of the first split light returned from the near-field target, the set of SPAD outputs is a first set of SPAD outputs, and the subset of SPADs is a first subset of SPADs; the optical combiner is further positioned to receive and direct a combination of the second split light and a second portion of the first split light returned from a far-field target estimated to be within a far-field range of the proximity sensing device toward the array of SPADs; the SPAD output selection and routing network is operable to couple the first set of SPAD outputs to a first subset of SPAD output pulse counters of the set of SPAD output pulse counters; the SPAD output selection and routing network is operable to couple a second set of SPAD outputs received from a second subset of SPADs in the array of SPADs to a second subset of SPAD output pulse counters of the set of SPAD output pulse counters. The proximity sensing device of claim 14.

16. 11. The proximity sensing device of claim 10, further comprising an enable circuit operable to connect a SPAD output in the set of SPAD outputs to the set of SPAD output pulse counters or to disconnect a SPAD output in the set of SPAD outputs from the set of SPAD output pulse counters.

17. A proximity sensing device, comprising: a frequency modulated continuous wave (FMCW) light source; an array of single photon avalanche diodes (SPADs); an optical splitter arranged to receive the light emitted by the FMCW light source and output a first split light and a second split light; an optical combiner positioned to receive and direct a combination of the second split light and a portion of the first split light returned from a target to the array of SPADs; a set of one or more optical elements that, in combination with the optical combiner, direct a coherent mixture of the second split light and the portions of the first split light toward a subset of SPADs in the array of SPADs.

18. 20. The proximity sensing device of claim 17, wherein the set of one or more optical elements consists of a monolithic optical element.

19. 20. The proximity sensing device of claim 18, wherein the monolithic optical element defines a transmit light pipe and a receive light pipe.

20. The proximity sensing device of claim 18 , wherein the monolithic optical element defines the optical splitter and the optical combiner.

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