EP4690833A1

EP4690833A1 - Photon counting image sensor device and method for operating a photon counting image sensor device

Info

Publication number: EP4690833A1
Application number: EP24711186.7A
Authority: EP
Inventors: Noam Zeev ESHEL; Roman Weisman
Original assignee: Sony Europe BV; Sony Semiconductor Solutions Corp
Current assignee: Sony Europe BV; Sony Semiconductor Solutions Corp
Priority date: 2023-03-29
Filing date: 2024-03-13
Publication date: 2026-02-11
Also published as: WO2024200001A1

Abstract

A sensor device comprises a pixel array including pixels circuits configured to generate digital values in response to incident radiation. Each of the pixel circuits comprise a Single Photon Avalanche Diode, SPAD, configured to provide an electrical pulse once a photon is detected. The pixel circuits further include a counter unit configured to generate a digital value based on the electrical pulses provided by the SPAD. In addition, the sensor device comprises a latch. A data input of a latch of a first pixel circuit is configured to be selectively coupled to an output of a counter unit of the first pixel circuit or to an output of a latch of a second pixel circuit.

Description

PHOTON COUNTING IMAGE SENSOR DEVICE AND METHOD FOR OPERATING A PHOTON COUNTING IMAGE SENSOR DEVICE

The present disclosure relates to a sensor device and a method for operating a sensor device. More particularly, the present disclosure relates to a sensor device including a single photon avalanche diode, SPAD.

BACKGROUND

An image sensor generally includes a readout circuit of some form for reading out pixel signal values from pixels in a pixel array. In this context, pixel arrays comprising single-photon avalanche diodes (SPADs) are very often used. SPADs have several advantages over photodiodes operating in the linear mode. They may provide a higher sensitivity and may have a very precise timing response. Therefore, arrays of SPADs may be applied to various applications requiring fast and precise depth map evaluation such as 3D imaging. For example, they may be used for determining the time-of-flight of optical pulses reflected by an object, thus measuring the distance to each point of the object. Alternatively, SPAD pixels can be used for photon counting applications, paving the way to an image with a wide dynamic range and low noise.

However, existing arrays of SPADs typically require complex readout and enable circuits, and corresponding signal paths, which may be a limiting factor in the overall size or number of SPADs in such arrays. Among these common read-out circuits are Analog to Digital Converters (ADCs) though which analog pixel signal values are read out in parallel and converted into digital form. They may use a conventional shift register or a holding device (e.g., a sample-and-hold circuit) and a tri-state buffer. These circuits require relatively high power consumption and a relatively large layout area. Thus, improved circuits are required for reading out pixel values for SPAD arrays.

SUMMARY

The present disclosure provides an improved sensor device.

To this purpose, the sensor device comprises a pixel array including pixels circuits configured to generate digital values in response to incident radiation. Each of the pixel circuits comprise a Single Photon Avalanche Diode, SPAD, configured to provide an electrical pulse once or in case a photon is detected. The pixel circuits further include a counter unit configured to generate a digital value based on the electrical pulses provided by the SPAD. In addition, the sensor device comprises a latch. A data input of a latch of a first pixel circuit is configured to be selectively coupled to an output of a counter unit of the first pixel circuit or to an output of a latch of a second pixel circuit.

A method for operating a sensor device described above comprises the following features: connecting, by the switching unit, data inputs of the latches of the pixel circuits to the outputs of the corresponding counter units of the pixel circuits, and receiving, by the latches of the pixel circuits, bits of digital values from the corresponding counter units in parallel. The latches are then disabled. Furthermore the method comprises the features: connecting, by the switching unit, the data input of the latch corresponding to the first pixel circuit to the output of the latch corresponding to the second pixel circuit, outputting, by the latch of the first pixel circuit, a bit corresponding to a digital value of the first pixel circuit, enabling, by a control unit, the latch of the first pixel circuit, and outputting, by the latch of the first pixel circuit, a bit corresponding to a digital value of the second pixel circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a simplified circuit diagram depicting an exemplary circuit configuration of a sensor device according to embodiments of the present technology.

FIG. 2A is a simplified circuit diagram depicting an exemplary circuit configuration of a pixel circuit according to embodiments of the present technology.

FIG. 2B is a truth table of a switching unit associated with the pixel circuit illustrated in FIG. 2A.

FIG. 3A is a simplified circuit diagram depicting an exemplary circuit configuration of a pixel array of the sensor device according to embodiments of the present technology.

FIG. 3B is a simplified diagram depicting operation modes of the sensor device according to embodiments of the present technology.

FIG. 4 is simplified example depicting readout patterns for the pixel array according to embodiments of the present technology.

FIG. 5 is a simplified diagram depicting a method for operating the sensor device according to embodiments of the present technology.

FIG. 6 is a diagram depicting a distance measurement apparatus according to embodiments of the present technology.

FIG. 7A is a block diagram depicting a specific configuration of a distance measurement apparatus according to embodiments of the present technology.

FIG. 7B is a block diagram depicting a specific configuration of the distance measurement apparatus according to embodiments of the present technology. FIG. 8A is a circuit diagram depicting a first example of a basic configuration of a SPAD according to embodiments of the present technology.

FIG. 8B is a circuit diagram depicting a second example of a basic configuration of a SPAD according to embodiments of the present technology.

FIG. 8C is a characteristic diagram showing current-voltage characteristics of a PN junction of the SPAD.

FIG. 9 is circuit diagram depicting an example of the internal makeup of a latch according to embodiments of the present technology.

FIG. 10A is a block diagram depicting an exemplary schematic configuration of the sensor device according to embodiments of the present technology.

FIG. 10B is a diagram depicting an exemplary chip configuration of the sensor device according to embodiments of the present technology.

FIG. 11 is a block diagram showing a schematic configuration example of a vehicle control system that is an example of a mobile body control system according to embodiments of the present technology.

FIG. 12 is a diagram showing an example of an installation position of the distance measurement apparatus according to embodiments.

DETAILED DESCRIPTION

Embodiments for implementing techniques of the present disclosure (also referred to as “embodiments” in the following) will be described below in detail using the drawings. The techniques of the present disclosure are not limited to the described embodiments, and various numerical values and the like in the embodiments are illustrative only. The same elements or elements with the same functions are denoted by the same reference signs.

The terms "having", "containing", "including", "comprising" and the like are open, and the terms indicate the presence of stated structures, elements or features but do not preclude the presence of additional elements or features. The articles "a", "an" and "the" are intended to include the plural as well as the singular, unless the context clearly indicates otherwise.

Connected electronic elements may be electrically connected through a direct and/or low-resistive connection, e.g., through a conductive line. The terms “electrically connected” and “electrically coupled” may, in addition to a direct electric connection, also include a connection through other electronic elements provided and suitable for permanent and/or temporary signal transmission and/or transmission of energy. For example, electronic elements may be electrically coupled through resistors, capacitors, and switches such as transistors or transistor circuits, e.g. FETs (field effect transistors), transmission gates, and others. The load path of a transistor is the controlled path of a transistor. For example, a voltage applied to a gate of a FET controls by field effect the current flow through the load path between source and drain.

FIG. 1 illustrates a configuration example of a sensor device 100 according to an embodiment of the present technology. The sensor device 100 may include a pixel array 10 including pixels circuits 12 that may generate digital values in response to incident radiation. In some examples, the pixel circuits 12 of the pixel array 10 may be arranged in in rows and columns. In greater detail, each of the pixel circuits 12 may comprise a Single Photon Avalanche Diode (SPAD) 14, a counter unit 16, and a latch 18 that may be electrically coupled to each other.

Each of the SPADs 14 may provide an electrical pulse once a photon is detected. In general, a SPAD is based around a semi-conductor p-n junction that may be illuminated with ionizing radiation such as gamma, x-rays, beta and alpha particles along with a wide portion of the electromagnetic spectrum ranging from ultraviolet (UV) through the visible wavelengths and into the infrared (IR). A large avalanche of current carriers may be triggered from a single photon-initiated carrier. More specifically, the SPADs 14 may each be configured as a p-n junction biased above breakdown Voltage by an excess voltage of a few volts. Operated in the so-called Geiger mode, the SPADs 14 may react on single photons. A primary carrier resulting from the absorption of a photon may generate a nearly-infinite number of secondary electron-hole pairs by impact ionization.

According to embodiments, the SPADs 14 may be CMOS -implemented and may comprise one or more quenching (recharging) transistors, a CMOS inverter, and an output transistor (not shown in the Fig. 1).

The counter unit 16 of each pixel circuit 12 may generate a digital value in form of bits or counterbits based on the electrical pulses provided by the respective SPAD 14. The counter units 16 may comprise various architectures such as a counter-ramp architecture and may be configured as 8-bit counters, a 9-bit counters or may be of any bit length.

The latch 18 of each pixel circuit 12 may be configured as a D-latch, also known as gated D-latch, transparent latch, data latch, or simply gated latch. The latches 18 have a data input D, an enable input E, and outputs Q and Q (where Q is always the opposite of Q). The output Q of the latches 18 is not relevant to the operations described herein, and thus is not illustrated in the figures. A property of the latches 18 is that when the enable input E is logical high (i.e., EN=1) the signal at the input D propagates directly through the circuit to the output Q. The latch 18 may then be transparent or enabled. This means that when the signal at the input D changes, the latch 18 propagates the change to Q essentially immediately (such that Q=D, i.e., without waiting for a next clock cycle). This is in contrast to a flip-flop, which would propagate the change at D only when the next clock pulse arrives. Furthermore, when the enable input E is logical low (i.e., EN=0), the output Q remains the same value that it was immediately before the input E switched to low (regardless of whether the input E subsequently changes). The latch 18 may then be disabled. In greater detail, a data input D of a latch 18 of a first pixel circuit 12A is configured to be selectively coupled (for example via a switching unit 20 of the sensor device 100 as described later on) to an output of a counter unit 16 of the first pixel circuit 12A or to an output Q of a latch 18 of a second pixel circuit 12B. The latter coupling is indicated in Fig. 1 by a dashed line connecting the pixel circuits 12A, 12B to each other.

Coupling the data input D of the first pixel circuit 10A to the output Q of the second pixel circuit 12B may allow forming a concatenated chain of latches 18 between of the pixel circuits 12A, 12B associated with respective rows. This allows an efficient read-out of bits of the digital values. Furthermore, this configuration avoids the need for shared bit-lines driven by a tri-state selection control on each row as done in common sensor circuits.

In this context, the sensor device 100 may further comprise a control unit configured to control the latches of the pixel circuits 12 to receive bits of the digital values from the counter units 16 in parallel, and to output the bits of the digital values serially by enabling each of the latches 18 sequentially or in a predetermined pattern. Corresponding control signals of the control unit are indicated by dashed lines in Fig. 1.

For example, when coupling the data inputs D of each of the latches 18 to the outputs of their respective counter units 16, the latches 18 may each receive a corresponding bit selected by the control unit via a control signal. Then, each latch 18 may be disabled, i.e., EN may be set to 0.

That is, in case that the data input E of the latch 18 of the first pixel circuit 12A is coupled to the output of the counter unit 16 of the first pixel circuit 12 A, the bit of the digital value of the first pixel circuit 12A may be received. And the latch 18 of the first pixel circuit 12A may be disabled (i.e., EN=0) to latch the pixel value.

In case that the data input of the latch 18 of the first pixel circuit 12A is coupled to the output of the latch 18 of the second pixel circuit 12B, a concatenated chain of latches 18 may be formed. The bit of the first pixel circuit 12A may be received and outputted via an output bus (not shown in Fig. 1). Then the latch 18 of the first pixel circuit 12A may be enabled (i.e., EN may be set to 1) so that the bit of the second pixel circuit 12B may be received and outputted to the output bus. This scheme may be repeated for additional pixel circuits 12 to enable a fast read-out of bits. That is, additional pixel circuits 12 may be concatenated as described above. Concatenating the pixel circuits 16 respectively their latches 18 may be achieved in parallel or in any suitable order.

In some examples, the sensor device 100 may comprise a switching unit 20 configured to switch the data input of the latch 18 of the first pixel circuit 12A between the output of the counter unit 16 of the first pixel circuit 12A and the output of the latch 18 of the second pixel circuit 12B.

In some examples, the switching unit 20 may comprise a multiplexer. In some examples, each of the pixel circuits 12 may comprise a switching unit 20 coupled to the counter unit 16 and the latch 18 of the respective pixel circuits 12 as shown in Fig. 1.

In some examples, as described above, the pixel circuits 12 may be arranged in in rows and columns.

In some examples, as described above, the SPADs 14 may be CMOS -implemented and configured to be operated in the Geiger mode.

Furthermore, in some examples, each SPAD 14 may be associated with one or more quenching/recharging transistors.

FIG. 2A illustrates an exemplary pixel circuit 12 according to embodiments of the present technology. The pixel circuit 12 may be representative for the pixel circuits 12 of the pixel array 100 including the first- and second pixel circuit 12A, 12B shown in Fig. 1. The pixel circuit 12 may comprise the counter unit 16 which is configured as a 9-bit counter that provides bits or counterbits CN to the switching unit 22 in response to the electrical pulses received from the SPAD 14. In this configuration, the switching unit 20 may be configured as a multiplexer that receives control signals SO, SI, S2, S3 for selecting and connecting one of its inputs to the data input D of the latch 18. More specifically, the control signals SO, SI, S2, S3 may cause the switching unit 20 to connect one of its inputs to the data input D of the latch to provide a counterbit CN, which is received by the latch 18 as Sout. In this case, the data input D of the latch 18 is coupled via the switching unit 20 to the output of the counter unit 16. In addition, the control signals SO, SI, S2, S3 may cause the switching unit 20 to connect its input indicated as Latchin in Fig. 2A to the data input D of the latch 18 to provide counterbits CN received by another pixel circuit 12 (not shown in Fig. 2A). In this case, the data input D of the latch 18 is coupled via the switching unit 20 to an output Q of a latch 18 corresponding to the other pixel circuit 12. In Fig. 2A, the switching unit 20 is shown as being part of the pixel circuit 12. According to embodiments, the switching unit 22 may also be arranged externally from the pixel circuit 12 saving some in-pixel logic.

Fig. 2B illustrates a corresponding truth table of the switching unit 20.

Fig. 3A illustrates an exemplary pixel array 10 according to embodiments of the present technology. In this example, the pixel circuits 12 may be arranged in rows row<0>, . . . , row<n> and columns col<0>, . . . , col<n>. The sensor device 100 may further comprise a control unit 22 that provides the control signals SO,

51, S2, S3 described above for operating the switching unit 20. In addition to the control signals SO, SI,

52, S3, the control unit 20 may provide control signal Slatch for enabling/disabling the latches 18 (i.e., setting EN to 1 or 0). This is illustrated schematically in Fig. 3A by corresponding arrows. In detail, the control unit 22 may operate the latches 18 to receive bits of the digital values from the counter units 16 in parallel and to output the bits of the digital values serially by enabling each of the latches 18 sequentially or in a predetermined pattern. Fig. 3B illustrates the operation modes of the sensor device 100 in more detail. For example, in the first line of Fig. 3B, the control unit 22 may operate the switching unit 20 via the control signals SO, SI, S2, S3 to provide a specific counterbit CN to the latches 18. For example, referring to the truth table of Fig. 2B, the respective control signals SO, SI, S2, S3 to provide the counterbit CN0 to all latches 18 in parallel may be S0=Sl=S2=S3=0. To keep this value for read-out (also known as latching), the latches 18 may be disabled via the control signal Slatch, e.g., by setting EN to 0. In this case, each of the latches 18 has at its respective output Q the value CN0. The counterbits CN0 of row<0> may then be read to the output bus (not shown in Fig. 3B). Afterwards, the latches 18 of the pixel circuits 12 in row<0> may be enabled via the control signal Slatch, e.g., by setting EN=1. This is shown in the second line in Fig. 3B. Following this, the counterbits CN0 of row<l> may propagate through the latches 18 in row<0> to the output bus. Then the latches 18 of row<l> may be enabled while keeping the latches of row<0> enabled. Subsequently, the counterbits CN0 of the row<2> may propagate through the latches 18 in row<l> and row<0>. This scheme may be repeated sequentially for the remaining rows row<3>, ... , row<n-l>, row<n> as illustrated in Fig. 3B. With this pixel configuration it may be possible to form a concatenated chain of latches 18 between several pixel circuits 12 for a faster read-out. This procedure may then also be applied to read-out the remining counterbits CN. In this respect, different read-out patterns may be applied by forming different concatenated chains of latches 18.

Fig. 4 illustrates a simplified example of readout patterns for the pixel array 10 according to embodiments of the present technology. For example, multiple latch chains may be formed for a single column col<0>, ... , col<n>. To keep the description simple, the read-out pattern of col<0>, indicated in Fig. 3a through a dashed rectangle, is considered in the following. As illustrated in Fig. 4, different latches 18 pertaining to pixel circuits 12 in different rows in col<0> may be concatenated and read-out in parallel. On the left side of Fig. 4 two parallel latch chains may be formed by concatenating latches 18 as described above. On the right side four parallel latch chains may be formed. Multiple latch chains require less clocks to read the bits. They also may increase the read-out speed since each cycle may be faster as it has less chained latches 18. In this context, different numbers of parallel latch chains may be possible per column col<0>, . . . , col<n>.

FIG. 5 is a simplified diagram depicting a method 1000 for operating the sensor device 100 according to embodiments of the present technology.

In step SI 10, the switching unit 20 may switch data inputs D of the latches 18 of the pixel circuits 12 to the outputs of the corresponding counter units 16 of the pixel circuits 12.

In step S120, the latches 18 of the pixel circuits 12 may receive bits of digital values from the corresponding counter units 16 in parallel. The latches 18 may then be disabled as described above.

In step SI 30, the switching unit 20 may connect the data input D of the latch 18 corresponding to the first pixel circuit 12A to the output Q of the latch 18 corresponding to the second pixel circuit 12B. In step S140, the latch 18 of the first pixel circuit 12A may receive a bit corresponding to a digital value of the first pixel circuit 12A.

In step S150, the control unit 22 may enable the latch 18 of the first pixel circuit 12A.

In step SI 60, the latch 18 of the first pixel circuit 12A may output a bit corresponding to a digital value of the second pixel circuit 12B.

In step SI 70, the switching unit 20 may connect a data input D of the latch 18 corresponding to the second pixel circuit 12B to an output Q of a latch 18 corresponding to a third pixel circuit 12C.

In step S180, the control unit 22 may enable the latch 18 of the second pixel circuit 12B while keeping the latch 18 of the first pixel circuit 12A enabled.

In step SI 90, the latch 18 of the second pixel circuit 12B and the latch 18 of the first pixel circuit 12A may be outputting a bit corresponding to a digital value of the third pixel circuit 12C.

As described with regard to Figs. 3 A to 4, the latches 18 may be enabled sequentially or in a predetermined sequence.

According to embodiments, the sensor device 100 described above may be implemented in a photon counting apparatus.

In general, photon counting is a technique in which individual photons are counted using a SPAD as described in the embodiments herein. A single-photon detector may emit a pulse of signal for each detected photon, in contrast to a normal photodetector, which generates an analog signal proportional to the photon flux. The number of pulses (but not their amplitude) is counted, giving an integer number of photons detected per measurement interval. The counting efficiency is determined by the quantum efficiency and the apparatus's electronic losses. Photon counting apparatuses may eliminate gain noise and may have an improved temporal resolution.

For example, the photon counting apparatus according to the present technology may be used in Fibercommunication applications, Quantum information sciences, Quantum encryption, Medical imaging applications, Light detection and ranging applications, DNA sequencing, Astrophysics, and Materials sciences among others.

For example, the sensor device 100 may be implemented in a distance measurement apparatus.

Fig. 6 illustrates a configuration example of a distance measurement apparatus 1 to which the embodiments of the present technology may be applied. The distance measurement apparatus 1 may adopt, as a measurement method for measuring a distance to a subject S that is a measurement object, a Time of Flight (ToF) method of measuring time until light (for example, laser light) having been radiated toward the subject S returns after being reflected by the subject S. In order to realize distance measurement by the ToF method, the distance measurement apparatus 1 according to the present embodiment may include a light detection apparatus 300 comprising the sensor device 100 described above and a light source 200.

Figs. 7A and 7B show a specific configuration of the distance measurement apparatus 1 according to embodiments. For example, the light source 200 may have a laser driver 210, a laser light source 220, and a diffusing lens 230 and radiates laser light toward the subject S. The laser driver 210 may drive the laser light source 220 under control of a control portion 400. The laser light source 220 may comprise, for example, a semiconductor laser and emits laser light by being driven by the laser driver 210. The diffusing lens 230 may diffuse laser light emitted from the laser light source 220 and may radiate the diffused laser light toward the subject S.

According to embodiments, the light detection apparatus 300 may comprise a light-receiving lens 310, the light sensor 100, and a logic circuit 330 and may receive reflected laser light that is radiated laser light emitted from a laser radiating portion 200 and is reflected on the subject S and returns back. The lightreceiving lens 310 may collect reflected laser light from the subject S on a light-receiving surface of the sensor device 100. The sensor device 100 may receive the reflected laser light from the subject S via the light-receiving lens 310 in units of a pixel and photoelectrically converts the reflected laser light. An output signal of the sensor device 100 may be is supplied to the control portion 40 via the logic circuit 330. Details of the sensor device 100 have been described above.

For example, the control portion 400 may comprise a CPU (Central Processing Unit) or the like, and controls the light source 200 and the sensor device 100, and measures time period t from the time point of radiation of laser light that is emitted from the light source 200 toward the subject S to the time point of returning after being reflected on the subject S. A distance U to the subject S can be obtained based on the measured time period t.

As a method of measuring time period t, time period t may be measured by starting a timer at a timing where pulse light is radiated from the light source 200 and stopping the timer at a timing where the pulse light is received by the light detection apparatus 300. As another method of time measurement, pulse light may be radiated from the light source 200 at a predetermined period, a period upon the light detection apparatus 300 receiving the pulse light may be detected, and time period t may be measured based on a phase difference between the period of light emission and the period of light reception. Time measurement is executed a plurality of times and time period t is measured by detecting a peak of a histogram created by stacking up a plurality of measured times.

Figs. 8A and 8B illustrate exemplary configurations of the SPAD 14 according to embodiments described above. The SPAD 14 applied in the sensor device 100 may be configured as follows.

The first exemplary configuration for the SPAD 14 is an example in which a load circuit 55 may a resistive element R. In the SPAD 14 of the pixel circuit 12 according to the first example, a cathode electrode may be connected via the resistive element R that is the load circuit 55 to a terminal 52 to which a power supply voltage VDD is applied and an anode electrode is connected to a terminal 53 to which an anode voltage Vbd is applied. As the anode voltage Vbd, a negative voltage large enough to cause an avalanche multiplication is applied. In addition, a cathode voltage VCA of the SPAD 14 may be derived as a SPAD output (a pixel output) via a waveform shaping circuit 54 constituted by a P-type MOS transistor Q and an N-type MOS transistor Qn.

A voltage equal to or higher than a breakdown voltage VBD (for example, -50 to -10 V) may be applied to the SPAD 14. An excess voltage equal to or higher than the breakdown voltage Van is referred to as an excess bias voltage VEX and is generally a voltage of around 2 to 5 V. This is a larger value than a conventional photodiode. The SPAD 14 may operate in a region called a Geiger mode that is devoid of a DC stabilization point. FIG. 8C shows I (current)-V (voltage) characteristics of a PN junction of the SPAD 14.

The second example of the SPAD 14 is an example in which the load circuit 55 may comprise a constantcurrent source such as a P-type MOS transistor QL. The SPAD 14 according to the second example only differs from the SPAD 14 according to the first example shown in FIG. 8A in that the load circuit 55 in the SPAD 14 according to the first example has been changed from the resistive element R to the P-type MOS transistor QL and other circuit components are basically the same.

Fig. 9 illustrates an exemplary configuration of the latches 18 according to embodiments described herein.

Fig. 10A illustrates an exemplary configuration of the sensor device 100 according to embodiments including additional circuits. As shown in Fig. 10 A, the sensor device 100 may comprise a timing control circuit 143, a drive circuit 144, and an output circuit 145. In the following description, the timing control circuit 143, the drive circuit 144, and the output circuit 145 may be referred to as peripheral circuits. The control unit 22 according to embodiments described above may be comprised in the timing control circuit 143.

Pixel drive lines LD (extending in the vertical direction in the figure) may be connected to the columns of the plurality of SPADs 14 and output signal lines LS (extending in the horizontal direction in the figure) are connected to the rows. One ends of the pixel drive lines LD are connected to output ends of the drive circuit 144 corresponding to the columns and one ends of the output signal lines LS are connected to input ends of the output circuit 145 corresponding to the rows.

The drive circuit 144 may include a shift register, an address decoder, and the like and may drive the SPADs 14 of the pixel array 10 all at the same time, column by column, or the like. Thus, the drive circuit 144 may include at least a circuit that applies a quench voltage V QCH to each SPAD 14 in a selected column of the pixel array 10 and a circuit that applies a selection control voltage V SEL to each SPAD pl4 in the selected column. Then, the drive circuit 144 may select the SPADs 14 used to detect the incidence of photons column by column by applying the selection control voltage V SEL to a pixel drive line LD corresponding to a column to be read. Signals (referred to as detection signals) V OUT output from the SPADs 14 in the column selected and scanned by the drive circuit 144 are input to the output circuit 145 through the output signal lines LS. The output circuit 145 may output the detection signals V OUT input from the SPADs 14 to a SPAD.

Fig. 10B illustrates a diagram showing an exemplary chip configuration of the sensor device 100 according to embodiments. As shown in Fig. 10B, the sensor device 100 may have, for example, a structure of a bonded chip 500 in which a first chip 501 and a second chip 502 are vertically bonded together. The first chip 501 may be, for example, a semiconductor chip in which the photoelectric conversion portions of the SPADs 14 are arranged in a matrix and the second chip 502 may be, for example, a semiconductor chip in which the reading circuits described above of the SPADs 14, the peripheral circuits, and the like are formed.

For example, so-called direct bonding in which bonding surfaces of the first and second chips 501 and 502 are flattened and the first and second chips 501 and 502 are bonded together by intermolecular force may be used to bond the first and second chips 51 and 52 together. However, the present technology is not limited to this, and for example, so-called Cu-Cu bonding in which electrode pads made of copper (Cu) formed on the bonding surfaces of the first and second chips 501 and 502 are bonded together, other bump bonding, or the like may be used.

The first and second chips 501 and 502 may be electrically connected, for example, via a connecting portion such as a through-silicon via (TSV) penetrating the semiconductor substrate. For example, a so- called twin TSV method in which two TSVs, a TSV provided on the first chip 501 and a TSV provided from the first chip 501 to the second chip 502, are connected on outer surfaces of the chips, a so-called shared TSV method in which the first and second chips 501 and 502 are connected by a TSV penetrating from the first chip 501 to the second chip 502, orthe like may be adopted for the connection using TSVs.

However, the first and second chips 501 and 502 may be electrically connected via a Cu-Cu bonding portion or a bump bonding portion when Cu-Cu bonding or bump bonding is used to bond the first and second chips 501 and 502 together.

The technique according to the present technology can be applied to various products. Hereinafter, a more specific application example will be described. For example, the technique according to the present technology may be realized as a ranging apparatus to be mounted to any of various types of mobile bodies including an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility an airplane, a drone, an ocean vessel, a robot, construction machinery and agricultural and farm machinery (a tractor).

Fig. 11 illustrates a block diagram showing a schematic configuration example of a vehicle control system 7000 that represents an example of a mobile body control system to which the technique according to the present technology may be applied. The vehicle control system 7000 includes a plurality of electronic control units that are connected via a communication network 7010. In the example shown in Fig. 11, the vehicle control system 7000 includes a drive system control unit 7100, a body system control unit 7200, a battery control unit 7300, an external vehicle information detecting unit 7400, an internal vehicle information detecting unit 7500, and an integrated control unit 7600. The communication network 7010 that connects the plurality of control units may be a vehicle-mounted communication network compliant with an arbitrary standard such as a CAN (Controller Area Network), a LIN (Local Interconnect Network), a LAN (Local Area Network), or FlexRay (registered trademark).

Each control unit includes a microcomputer that performs arithmetic processing in accordance with various programs, a storage portion that stores programs to be executed by the microcomputer, parameters to be used in various calculations, and the like, and a drive circuit that drives various apparatuses which are control targets. Each control unit includes a network I/F for communicating with other control units via the communication network 7010 and a communication I/F for communicating with apparatuses, sensors, and the like inside and outside the vehicle via wired communication or wireless communication. Fig. 11 illustrates, as functional components of the integrated control unit 7600, a microcomputer 7610, a general -purpose communication I/F 7620, a dedicated communication I/F 7630, a positioning portion 7640, a beacon receiving portion 7650, an on-board device I/F 7660, an audio/video output portion 7670, a vehicle-mounted network I/F 7680, and a storage portion 7690. The other control units similarly include a microcomputer, a communication I/F a storage portion, and the like.

The drive system control unit 7100 controls operations of apparatuses related to a drive system of a vehicle in accordance with various programs. For example, the drive system control unit 7100 functions as a control apparatus of a drive force generation apparatus for generating a drive force of the vehicle such as an internal engine or a drive motor, a control apparatus of a drive force transmission mechanism for transmitting the drive force to wheels, a control apparatus of a steering mechanism for adjusting a steering angle of the vehicle, and a control apparatus of a braking apparatus that generates a brake force of the vehicle. The drive system control unit 7100 may have functions as a control apparatus of an ABS (Antilock Brake System), a control apparatus of ESC (Electronic Stability Control), or the like.

A vehicle state detecting portion 7110 is connected to the drive system control unit 7100. For example, the vehicle state detecting portion 7110 includes at least one of a gyroscope sensor that detects an angular velocity of a rotational motion of a shaft of a vehicle body an acceleration sensor that detects an acceleration of the vehicle, and a sensor for detecting an operation amount of a gas pedal, an operation amount of a brake pedal, a steering angle of a steering wheel, the number of revolutions of an engine, a rotational speed of a wheel, or the like. The drive system control unit 7100 performs arithmetic processing using a signal input, from the vehicle state detecting portion 7110 and controls an internal engine, a drive motor, an electric power steering apparatus, a brake apparatus, or the like.

The body system control unit 7200 controls operations of various apparatuses mounted to the vehicle body in accordance with various programs. For example, the body system control unit 7200 functions as a control apparatus of a keyless entry system, a smart key system, a power window apparatus, or various lamps such as head lamps, tail lamps, brake lamps, turn indicators, and fog lamps. In this case, radio waves or signals of various switches which are transmitted from a portable device that substitutes as a key may be input to the body system control unit 7200. The body system control unit 7200 accepts input of the radio waves or signals and controls a door lock apparatus, the power window apparatus, the lamps, and the like of the vehicle.

The battery control unit 7300 controls a secondary battery 7310 that is a power supply source of the drive motor in accordance with various programs. For example, information on a battery temperature, a battery output voltage, a battery remaining capacity, or the like is input to the battery control unit 7300 from a battery apparatus including the secondary battery 7310. The battery control unit 7300 uses these signals to perform arithmetic processing to control temperature regulation of the secondary battery 7310 or to control a cooling apparatus or the like included in the battery apparatus.

The external vehicle information detecting unit 7400 detects information on an exterior of the vehicle that is mounted with the vehicle control system 7000. For example, at least one of an imaging portion 7410 and an external vehicle information detecting portion 7420 is connected to the external vehicle information detecting unit 7400. The imaging portion 7410 includes at least, one of a ToF (Time of Flight) camera, a stereo camera, a monocular camera, an infrared camera, and other cameras. For example, the external vehicle information detecting portion 7420 includes at least one of an environmental sensor for detecting present weather or meteorological phenomena and an ambient information detection sensor for detecting other vehicles, obstacles, pedestrians, or the like around the vehicle mounted with the vehicle control system 7000.

For example, the environmental sensor may be at least one of a raindrop sensorthat detects rainy weather, a fog sensor that detects fog, a sunshine sensor that detects a degree of sunshine, and a snow sensor that detects snowfall. The ambient information detection sensor may be at least one of an ultrasonic sensor, a radar apparatus, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) apparatus. The imaging portion 7410 and the external vehicle information detecting portion 7420 may be respectively included as an independent sensor or an independent apparatus or may be included as an apparatus that integrates a plurality of sensors or apparatuses.

Fig. 12 is a diagram showing an example of installation positions of the imaging portion 7410 and the external vehicle information detecting portion 7420. For example, imaging portions 7910, 7912, 7914, 7916, and 7918 are provided at least one position among a front nose, a side mirror, a rear bumper, a rear door, and an upper part of a front glass inside a cabin of a vehicle 7900. The imaging portion 7910 that is provided on the front nose and the imaging portion 7918 that is provided in the upper part of the front glass inside the cabin mainly acquire an image of the front of the vehicle 7900. The imaging portions 7912 and 7914 that are provided on the side mirrors mainly acquire an image of the sides of the vehicle 7900. The imaging portion 7916 that is provided on the rear bumper or the rear door mainly acquires an image of the rear of the vehicle 7900. The imaging portion 7918 that is provided in the upper part of the front glass inside the cabin is mainly used to detect vehicles ahead, pedestrians, obstacles, traffic lights, traffic signs, lanes, and the like. Fig. 12 shows an example of photographic ranges of the respective imaging portions 7910, 7912, 7914, and 7916. An imaging range a represents an imaging range of the imaging portion 7910 that is provided on the front nose, imaging ranges b and c respectively represent imaging ranges of the imaging portions 7912 and 7914 that are provided on the side mirrors, and an imaging range d represents an imaging range of the imaging portion 7916 that is provided on the rear bumper or the rear door. For example, by superimposing image data captured by the imaging portions 7910, 7912, 7914, and 7916, a bird's-eye view image of the vehicle 7900 as viewed from above is obtained.

For example, external vehicle information detecting portions 7920, 7922, 7924, 7926, 7928, and 7930 that are provided in the front, the rear, the sides, a comer, and the upper part of the front glass inside the cabin of the vehicle 7900 may be ultrasonic sensors or radar apparatuses. For example, the external vehicle information detecting portions 7920, 7926, and 7930 provided on the front nose, the rear bumper, the rear door, and the upper part of the front glass inside the cabin of the vehicle 7900 may be LIDAR apparatuses. The external vehicle information detecting portions 7920 to 7930 are mainly used to detect vehicles ahead, pedestrians, obstacles, and the like.

Let us return to Fig. 11 to continue with the description. The external vehicle information detecting unit 7400 causes the imaging portion 7410 to capture an image of the exterior of the vehicle and receives captured image data. In addition, the external vehicle information detecting unit 7400 receives detection information from the external vehicle information detecting portion 7420 being connected thereto. When the external vehicle information detecting portion 7420 is an ultrasonic sensor, a radar apparatus, or a LIDAR apparatus, the external vehicle information detecting unit 7400 causes the external vehicle information detecting portion 7420 to transmit ultrasonic waves, electromagnetic waves, or the like and receives information on received reflected waves. Based on the received information, the external vehicle information detecting unit 7400 may perform object detection processing or distance detection processing with respect to people, vehicles, obstacles, signs, characters on road surfaces, and the like. Based on the received information, the external vehicle information detecting unit 7400 may perform environmental recognition processing for recognizing rainfall, fog, road surface conditions, or the like. Based on the received information, the external vehicle information detecting unit 7400 may calculate a distance to an object outside of the vehicle.

In addition, based on received image data, the external vehicle information detecting unit 7400 may perform image recognition processing or distance detection processing for recognizing people, vehicles, obstacles, signs, characters on road surfaces, and the like. The external vehicle information detecting unit 7400 may perform processing such as distortion correction or positioning with respect to the received image data and composite the image data captured by different imaging portions 7410 to generate a bird's-eye view image or a panoramic image. The external vehicle information detecting unit 7400 may perform viewpoint transformation processing using image data captured by different imaging portions 7410.

The internal vehicle information detecting unit 7500 detects information on an interior of the vehicle. For example, a driver state detecting portion 7510 that detects a state of a driver is connected to the internal vehicle information detecting unit 7500. The driver state detecting portion 7510 may include a camera that captures an image of the driver, a biometric sensor that detects biological information of the driver, a microphone that collects sound inside the cabin, or the like. For example, the biometric sensor is provided on a seat surface, the steering wheel, or the like, and detects biological information of a passenger sitting on the seat or the driver holding the steering wheel. Based on detection information input from the driver state detecting portion 7510, the internal vehicle information detecting unit 7500 may calculate a degree of fatigue or a degree of concentration of the driver or may determine whether or not the driver has fallen asleep. The internal vehicle information detecting unit 7500 may perform processing such as noise cancellation processing with respect to a collected sound signal.

[0106] The integrated control unit 7600 controls overall operations in the vehicle control system 7000 in accordance with various programs. An input portion 7800 is connected to the integrated control unit 7600. The input portion 7800 is realized by an apparatus on which a passenger can perform input operations such as a touch panel, a button, a microphone, a switch, or a lever. Data obtained by subjecting sound input from the microphone to speech recognition may be input to the integrated control unit 7600. For example, the input portion 7800 may be a remote-controlled apparatus using infrared light or other radio waves or an externally-connected device such as a mobile phone or a PDA (Personal Digital Assistant) that accommodates operations of the vehicle control system 7000. For example, the input portion 7800 may be a camera, in which case a passenger can input information by gesturing to the camera. Alternatively, data obtained by detecting a motion of a wearable apparatus being worn by a passenger may be input. Furthermore, for example, the input portion 7800 described above may include an input control circuit or the like which generates an input signal based on information input by a passenger or the like using the input portion 7800 and which outputs the generated input signal to the integrated control unit 7600. By operating the input portion 7800, a passenger or the like inputs various types of data and issues instructions to perform processing operations with respect to the vehicle control system 7000.

The storage portion 7690 may include a ROM (Read Only Memory) that stores various programs to be executed by the microcomputer and a RAM (Random Access Memory) that stores various parameters, calculation results, sensor values, or the like. In addition, the storage portion 7690 may be realized by a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, a magneto-optical storage device, or the like.

The general -purpose communication I/F 7620 is a general -purpose communication I/F that mediates communication with various devices that are present in an external environment 7750. The general- purpose communication I/F 7620 may implement a cellular communication protocol such as GSM (registered trademark) (Global System of Mobile communications), WiMAX, LTE (Long Term Evolution), or LTE-A (LTE-Advanced) or another wireless communication protocol such as wireless LAN (also referred to as Wi-Fi (registered trademark)) or Bluetooth (registered trademark). For example, the general -purpose communication I/F 7620 may connect to a device (for example, an application server or a control server) present on an external network (for example, the Internet, a cloud network, or a company-specific network) via a base station or an access point. In addition, for example, the general- purpose communication I/F 7620 may connect to a terminal (for example, a terminal belonging to the driver or a pedestrian, a terminal of a store, or an MTC (Machine Type Communication) terminal) that is present in a vicinity of the vehicle using P2P (Peer To Peer) technology.

The dedicated communication I/F 7630 is a communication I/F that supports a communication protocol designed to be used in a vehicle. For example, the dedicated communication I/F 7630 may implement a standard protocol such as WAVE (Wireless Access in Vehicle Environment) that is a combination of IEEE 802. l ip constituting a lower layer and IEEE 1609 constituting a higher layer, DSRC (Dedicated Short Range Communications), or a cellular communication protocol. Typically, the dedicated communication I/F 7630 carries out V2X communication that is a concept including one or more of communication between vehicles (Vehicle to Vehicle communication), communication between a road and a vehicle (Vehicle to Infrastructure communication), communication between a vehicle and a home (Vehicle to Home communication), and communication between a pedestrian and a vehicle (Vehicle to Pedestrian communication).

For example, the positioning portion 7640 receives a GNSS (Global Navigation Satellite System) signal from a GNSS satellite (for example, a UPS (Global Positioning System) signal from a UPS satellite) and executes positioning, and generates positional information including a latitude, a longitude, and an elevation of the vehicle. Alternatively the positioning portion 7640 may specify a current position by exchanging signals with a wireless access point or acquire positional information from a terminal such as a mobile phone, a PHS, or a smartphone with a positioning function.

For example, the beacon receiving portion 7650 receives radio waves or electromagnetic waves emitted from a radio station or the like installed on a road and acquires information such as a current position, congestions, closures, and required time. Alternatively, the function of the beacon receiving portion 7650 may be included in the dedicated communication I/F 7630 described above.

The on-board device I/F 7660 is a communication interface that mediates communication between the microcomputer 7610 and various on-board devices 7760 that are present inside the vehicle. The on-board device I/F 7660 may establish a wireless connection using a wireless communication protocol such as a wireless LAN, Bluetooth (registered trademark), NFC (Near Field Communication), or WUSB (Wireless USB). In addition, the on-board device I/F 7660 may establish, via a connection terminal (not illustrated) (and a cable when necessary), a wired connection such as USB (Universal Serial Bus), HDMI (registered trademark) (High-Definition Multimedia Interface), or MHL (Mobile High-definition Link). For example, the on-board devices 7760 may include at least one of a mobile device or a wearable device that is held or worn by a passenger and an information device to be carried onto or attached to the vehicle. Furthermore, the on-board devices 7760 may include a navigation apparatus that searches a route to an arbitrary destination. The on-board device I/F 7660 exchanges control signals and data signals with the on-board devices 7760.

The vehicle-mounted network I/F 7680 is an interface that mediates communication between the microcomputer 7610 and the communication network 7010. The vehicle-mounted network I/F 7680 transmits and receives signals and the like in accordance with a prescribed protocol that is supported by the communication network 7010.

The microcomputer 7610 of the integrated control unit 7600 controls the vehicle control system 7000 in accordance with various programs based on information acquired via at least one of the general-purpose communication I/F 7620, the dedicated communication I/F 7630, the positioning portion 7640, the beacon receiving portion 7650, the on-board device I/F 7660, and the vehicle-mounted network I/F 7680. For example, based on acquired information on the exterior and the interior of the vehicle, the microcomputer 7610 may calculate a control target value of the drive force generation apparatus, the steering mechanism, or the brake apparatus and output a control command to the drive system control unit 7100. For example, the microcomputer 7610 may perform cooperative control for the purpose of realizing functions of an ADAS (Advanced Driver Assistance System) including collision avoidance or crash mitigation of the vehicle, headway control based on inter-vehicular distance, cruise control, a collision warning of the vehicle, and a lane departure warning of the vehicle. In addition, by controlling the drive force generation apparatus, the steering mechanism, the brake apparatus, or the like based on acquired information on a periphery of the vehicle, the microcomputer 7610 may perform cooperative control for the purpose of automated driving or the like that enables the vehicle to travel autonomously without having to rely on operations by the driver.

The microcomputer 7610 may generate three-dimensional distance information between the vehicle and a surrounding object such as a structure or a person and create local map information including peripheral information of a current position of the vehicle based on information acquired via at least one of the general -purpose communication I/F 7620, the dedicated communication I/F 7630, the positioning portion 7640, the beacon receiving portion 7650, the on-board device I/F 7660, and the vehicle-mounted network I/F 7680. In addition, based on acquired information, the microcomputer 7610 may predict danger such as a collision involving the vehicle, an approach by a pedestrian or the like, or entering a closed road and generate a warning signal. For example, the warning signal may be a signal for generating a warning sound or turning on a warning lamp.

The audio/video output portion 7670 transmits an output signal of at least one of sound and an image to an output apparatus that is capable of audibly or visually notifying information to a passenger of the vehicle or to the outside of the vehicle. In an example shown in Fig. 11, an audio speaker 7710, a display portion 7720, and an instrument panel 7730 are exemplified as output apparatuses. For example, the display portion 7720 may include at least, one of an on-board display and a head-up display. The display portion 7720 may have an AR (Augmented Reality) display function. The output apparatus may be an apparatus other than those described above such as headphones, a wearable device such as a spectacletype display that is worn by a passenger, a projector, or a lamp. When the output apparatus is a display apparatus, the display apparatus displays, in various formats such as a text, an image, a table, and a graph, results obtained by various types of processing performed by the microcomputer 7610 or information received from other control units. In addition, when the output apparatus is an audio output apparatus, the audio output apparatus converts an audio signal constituted by reproduced speech data, acoustic data, or the like into an analog signal and auditorially outputs the converted analog signal. In the example shown in Fig. 11, at least two control units connected via the communication network 7010 may be integrated as a single control unit. Alternatively each control unit may be constituted by a plurality of control units, Furthermore, the vehicle control system 7000 may include other control units that are not illustrated. In addition, a part of or all of the functions assumed by any control unit in the description provided above may be shouldered by another control unit. In other words, as long as information is to be transmitted and received via the communication network 7010, prescribed arithmetic processing may be performed by any control unit. In a similar manner, a sensor or an apparatus connected to any control unit may be connected to another control unit and, at the same time, a plurality of control units may mutually transmit and receive detection information via the communication network 7010.

This concludes the description of an example of a vehicle control system to which the technique according to the present disclosure may be applied. The technique according to the present disclosure may be applied to, for example, the imaging portions 7910, 7912, 7914, 7916, and 7918 and external vehicle information detecting portions 7920, 7922, 7924, 7926, 7928, and 7930 among the configuration described above. In addition, by applying the technique according to the present disclosure, since the light detection apparatus 30 can accommodate a specified vehicle-mount temperature and perform a light detection operation in a wide temperature range without causing a latching current problem, for example, a vehicle control system capable of detecting an imaging object with high accuracy can be constructed.

The present technology can also be configured as described below:

[1] A sensor device (100) comprising: a pixel array (10) including pixels circuits (12) configured to generate digital values in response to incident radiation, each of the pixel circuits (12) comprising: a Single Photon Avalanche Diode, SPAD (14), configured to provide an electrical pulse once a photon is detected; a counter unit (16) configured to generate a digital value based on the electrical pulses provided by the SPAD (14); and a latch (18); wherein a data input (D) of a latch (18) of a first pixel circuit (12A) is configured to be selectively coupled to an output of a counter unit (16) of the first pixel circuit (12A) or to an output (Q) of a latch of a second pixel circuit (12B).

[2] The sensor device (100) according to [1], further comprising a control unit (22) configured to control the latches (18) of the pixel circuits to: receive bits of the digital values from the counter units (16) in parallel; and output the bits of the digital values serially by enabling each of the latches (18) sequentially or in a predetermined pattern.

[3], The sensor device (100) according to [1] or [2], wherein, in case that the data input of the latch (18) of the first pixel circuit (12A) is coupled to the output of the counter unit (16) of the first pixel circuit (12A), the bit of the digital value of the first pixel circuit is received, wherein the latch (18) of the first pixel circuit (12A) is disabled.

[4] The sensor device (100) according to any of [1] to [3] described above, wherein, in case that the data input of the latch (18) of the first pixel circuit (12A) is coupled to the output of the latch (18) of the second pixel circuit (12B), a concatenated chain of latches (18) is formed.

[5] The sensor device (100) according to any of [1] to [4] described above, further comprising a switching unit (20) configured to switch the data input of the latch (18) of the first pixel circuit (12A) between the output of the counter unit (16) of the first pixel circuit (12A) and the output of the latch (18) of the second pixel circuit (12B).

[6] The sensor device (100) according to [5], wherein the switching unit (20) comprises a multiplexer.

[7] The sensor device (100) according to [5] or [6], wherein each of the pixel circuits (12) comprises a switching unit (20) coupled to the counter unit (16) and the latch (18) of the respective pixel circuits (12).

[8] The sensor device (100) according to any of [1] to [7] described above, wherein the pixel circuits (12) are arranged in in rows (row<0>, . . . ., row<n>) and columns (col<0>, . . . , col<n>).

[9] The sensor device (100) according to any of [1] to [8] described above, wherein the SPADs (14) are CMOS-implemented and configured to be operated in the Geiger mode.

[10] The sensor device (100) according to any of [1] to [9] described above, wherein each SPAD (14) is associated with one or more quenching/recharging transistors.

[11] A method (1000) for operating a sensor device (100) according to any of [1] to [10] described above, the method comprising: connecting (SI 10), by the switching unit (20), data inputs (D) of the latches (18) of the pixel circuits (12) to the outputs of the corresponding counter units (16) of the pixel circuits (12); and receiving (S120), by the latches (18) of the pixel circuits (12), bits of digital values from the corresponding counter units (16) in parallel, wherein the latches (18) are disabled; connecting (S130), by the switching unit (20), the data input (D) of the latch (18) corresponding to the first pixel circuit (12A) to the output (Q) of the latch (18) corresponding to the second pixel circuit (12B); outputting (S140), by the latch (18) of the first pixel circuit (12A), a bit corresponding to a digital value of the first pixel circuit (12A); enabling, (S150) by the control unit (22), the latch (18) of the first pixel circuit (12A); and outputting (SI 60), by the latch (18) of the first pixel circuit (12A), a bit corresponding to a digital value of the second pixel circuit (12B). [12] The method (100) according to [11], further comprising: connecting (S170), by the switching unit (20), a data input (D) of the latch (18) corresponding to the second pixel circuit (12B) to an output (Q) of a latch (18) corresponding to a third pixel circuit (12C); enabling (S180), by the control unit (22), the latch (18) of the second pixel circuit (12B) while keeping the latch (18) of the first pixel circuit (12A) enabled; and outputting (S 190), by the latch ( 18) of the second pixel circuit ( 12B) and the latch ( 18) of the first pixel circuit (12A), a bit corresponding to a digital value of the third pixel circuit (12C). [13] The method (1000) according to [11] or [12], wherein the latches (18) are enabled sequentially or in a predetermined sequence.

Claims

1. A sensor device comprising: a pixel array including pixels circuits configured to generate digital values in response to incident radiation, each of the pixel circuits comprising: a Single Photon Avalanche Diode, SPAD, configured to provide an electrical pulse once a photon is detected; a counter unit configured to generate a digital value based on the electrical pulses provided by the SPAD; and a latch; wherein a data input of a latch of a first pixel circuit is configured to be selectively coupled to an output of a counter unit of the first pixel circuit or to an output of a latch of a second pixel circuit.

2. The sensor device according to claim 1, further comprising a control unit configured to control the latches of the pixel circuits to: receive bits of the digital values from the counter units in parallel; and output the bits of the digital values serially by enabling each of the latches sequentially or in a predetermined pattern.

3. The sensor device according to claim 1, wherein, in case that the data input of the latch of the first pixel circuit is coupled to the output of the counter unit of the first pixel circuit, the bit of the digital value of the first pixel circuit is received, wherein the latch of the first pixel circuit is disabled.

4. The sensor device according to claim 1, wherein, in case that the data input of the latch of the first pixel circuit is coupled to the output of the latch of the second pixel circuit, a concatenated chain of latches is formed.

5. The sensor device according to claim 1, further comprising a switching unit configured to switch the data input of the latch of the first pixel circuit between the output of the counter unit of the first pixel circuit and the output of the latch of the second pixel circuit.

6. The sensor device according to claim 5, wherein the switching unit comprises a multiplexer.

7. The sensor device according to claim 6, wherein each of the pixel circuits comprises a switching unit coupled to the counter unit and the latch of the respective pixel circuits.

8. The sensor device according to claim 1, wherein the pixel circuits are arranged in in rows and columns.

9. The sensor device according to claim 1, wherein the SPADs are CMOS -implemented and configured to be operated in the Geiger mode.

10. The sensor device according to claim 1, wherein each SPAD is associated with one or more quenching/recharging transistors.

11. A method for operating a sensor device according to claim 1, the method comprising: connecting, by the switching unit, data inputs of the latches of the pixel circuits to the outputs of the corresponding counter units of the pixel circuits; and receiving, by the latches of the pixel circuits, bits of digital values from the corresponding counter units in parallel, wherein the latches are disabled; connecting, by the switching unit, the data input of the latch corresponding to the first pixel circuit to the output of the latch corresponding to the second pixel circuit; outputting, by the latch of the first pixel circuit, a bit corresponding to a digital value of the first pixel circuit; enabling, by a control unit, the latch of the first pixel circuit; and outputting, by the latch of the first pixel circuit, a bit corresponding to a digital value of the second pixel circuit.

12. The method according to claim 11, further comprising: connecting, by the switching unit, a data input of the latch corresponding to the second pixel circuit to an output of a latch corresponding to a third pixel circuit; enabling, by the control unit, the latch of the second pixel circuit while keeping the latch of the first pixel circuit enabled; and outputting, by the latch of the second pixel circuit and the latch of the first pixel circuit, a bit corresponding to a digital value of the third pixel circuit.

13. The method according to claim 11, wherein the latches are enabled sequentially or in a predetermined sequence.