A digital silicon photomultiplier tube

Abstract

The invention discloses a digital silicon photomultiplier tube, comprising: a pixel array module, a logic circuit module, a counter / time digital converter, a counting rate comparison and judgment module and an enable control module; the digital SiPM sensor of the invention can compare and judge the current counting rate with the rated threshold counting rate, and feed back the comparison result to the enable control module, and the enable control module outputs an enable for adjusting the number n of effective pixels receiving photons to the pixel array module, thereby changing the probability of the effective pixel array in the pixel array module receiving photons to adjust the current counting rate of the counter / time digital converter, so that the current counting rate is within a suitable range, avoiding the occurrence of pile-up distortion, improving the accuracy of distance measurement, and reducing the power consumption required under the same detection effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar optical signal receiver systems, and in particular relates to a digital silicon photomultiplier tube. Background Art

[0002] In recent years, LiDAR sensors have been widely used in military and civilian fields such as 3D imaging, unmanned driving, biomedicine, topographic mapping, and aerospace. They have the advantages of high resolution, strong anti-active interference capability, high detection reliability, and large speed measurement range, and can detect the 3D image of the surrounding environment in real time. The digital SiPM (silicon photomultiplier) sensor has a single-photon level of detection sensitivity and adopts the time-correlated single photon counting (TCSPC) method. The principle is as follows: the SPAD device in the pixel circuit receives the photons in the laser echo reflected by the laser emitter after the laser is irradiated on the target object to be detected, triggering avalanche breakdown and generating a large current. The front-end circuit then quenches and resets the SPAD and compresses the pulse to obtain a voltage pulse signal, and then uses the time-to-digital converter to obtain the flight time information of the pulse.

[0003] In traditional schemes, the number of effective pixels in the pixel array that receive photons is immutable. Since the trigger probability P0 of a single SPAD is proportional to the laser power, the probability of the pixel array receiving photons will increase with the increase of laser power. This will increase the amount of data that the time-to-digital converter needs to process under the same detection effect. However, due to the limited data processing capacity of the time-to-digital converter, it will cause pile-up distortion and reduce the ranging accuracy. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a digital silicon photomultiplier tube. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] A digital silicon photomultiplier tube, comprising: a pixel array module, a logic circuit module, a counter / time digital converter, a counting rate comparison and judgment module and an enabling control module;

[0006] The feedback input end of the pixel array module is connected to the output end of the enable control module, and the output end of the pixel array module is connected to the input end of the logic circuit module; the pixel array module is used to receive photons in the laser echo in the field of view and generate a voltage pulse signal to output to the logic circuit module;

[0007] The output end of the logic circuit module is connected to the input end of the counter / time digital converter; the logic circuit module is used to output the voltage pulse signal to the counter / time digital converter for counting;

[0008] The feedback output terminal of the counter / time digital converter is connected to the input terminal of the counting rate comparison and judgment module; the counter / time digital converter is used to count the voltage pulse signal, convert the counting result into a digital signal and output it from the OUT terminal, and transmit the information of the current counting rate R to the counting rate comparison and judgment module through the feedback output terminal;

[0009] The output end of the counting rate comparison and judgment module is connected to the input end of the enabling control module; the counting rate comparison and judgment module is used to compare the current counting rate R with the maximum counting rate threshold R max and the minimum count rate threshold R min Perform comparison and output the comparison result to the enable control module;

[0010] The enable control module is used to generate an enable for adjusting the number n of effective pixels receiving photons according to the comparison result and output it to the pixel array module.

[0011] In one embodiment of the present invention, the comparison result includes: a first comparison result and a second comparison result;

[0012] The counting rate comparison and judgment module is also used to compare the current counting rate R with the maximum counting rate threshold R max Compare, if R>R max , then output the first comparison result to the enabling control module;

[0013] If R <R max , then the current counting rate R and the minimum counting rate threshold R min Compare, if R <R min , then the second comparison result is output to the enable control module. When R>R min When , the comparison ends;

[0014] The enable control module is further used to generate an enable for reducing the number n of effective pixels receiving photons according to the first comparison result and output it to the pixel array module, or

[0015] An enable for increasing the number n of effective pixels receiving photons is generated according to the second comparison result and output to the pixel array module.

[0016] Beneficial effects of the present invention:

[0017] The digital SiPM sensor of the present invention can set the rated maximum and minimum counting rate thresholds according to the size of the laser power, compare and judge the current counting rate with the rated threshold counting rate, and feed back the comparison result to the enabling control module. The enabling control module outputs the enabling of adjusting the number n of effective pixels receiving photons to the pixel array module, thereby changing the probability of the effective pixel array in the pixel array module receiving photons to adjust the size of the current counting rate of the counter / time digital converter, so that the current counting rate is within a suitable range, avoiding the occurrence of pile-up distortion, improving the accuracy of ranging, and reducing the power consumption required under the same detection effect.

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the structure of a digital silicon photomultiplier tube provided by an embodiment of the present invention;

[0020] Figure 2 It is a schematic diagram of the phenomenon of stacking realization;

[0021] Figure 3 A working flow chart of a digital silicon photomultiplier tube provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0023] Embodiment 1

[0024] See also Figure 1 A digital silicon photomultiplier tube includes: a pixel array module 100, a logic circuit module 200, a counter / time digital converter 300, a counting rate comparison and judgment module 400 and an enable control module 500.

[0025] The feedback input end of the pixel array module 100 is connected to the output end of the enable control module 500, and the output end of the pixel array module 100 is connected to the input end of the logic circuit module 200. The pixel unit in the pixel array module has a SPAD device and a front-end processing circuit. The pixel array module 100 is used to receive photons in the laser echo in the field of view. Under high voltage bias, the SPAD device is in Geiger mode and has single-photon sensitivity. A single photon can trigger avalanche breakdown to generate a large amount of photocurrent. The front-end processing circuit performs quenching, resetting, pulse compression and other processes. After a photon detection process is completed, a pulse signal with a suitable pulse width is generated, and the voltage pulse signal is output to the logic circuit module 200.

[0026] The output end of the logic circuit module 200 is connected to the input end of the counter / time digital converter 300. The logic circuit module 200 is implemented by a NOR gate plus a NAND gate, which integrates multiple voltage pulse signals from different SPAD devices input from the pixel array module 100 into one voltage pulse signal and outputs it to the counter / time digital converter 300 to count the voltage pulses triggered by photons, thereby saving circuit area and improving sensitivity.

[0027] The feedback output terminal of the counter / time digital converter 300 is connected to the input terminal of the counting rate comparison and judgment module 400; the counter / time digital converter 300 is used to process the voltage pulse signal input by the logic circuit module 200, count the voltage pulses generated by the photon trigger received during the laser echo reception process per unit time, convert the counting result into a digital signal and output it from the OUT terminal, and transmit the information of the current counting rate R to the counting rate comparison and judgment module 400 through the feedback output terminal.

[0028] The output end of the counting rate comparison and judgment module 400 is connected to the input end of the enabling control module 500. The counting rate comparison and judgment module 400 is used to compare the current counting rate R with the maximum counting rate threshold R. max and the minimum count rate threshold R min The comparison is performed and the comparison result is output to the enabling control module 500. In the counting rate comparison and judgment module 400, the maximum counting rate threshold R can be preset according to the laser power. max and the minimum count rate threshold R min , the current count rate R of the counter / time digital converter 300 is compared with R max , R min The comparison and judgment are performed, and the comparison result is output to the input end of the enable control module 500 through the output end. In this embodiment, the counting rate comparison and judgment module sets the rated maximum counting rate threshold R according to the corresponding relationship between the counting rate and the histogram accumulation result. max and the minimum count rate threshold R min , corresponding to the optimal histogram accumulation result. Compare the counting rate of the counter / time digital converter 300 with the rated threshold, and after the comparison is completed, output the feedback signal to the enable control module 500;

[0029] Since the trigger probability P0 of a single SPAD is proportional to the laser power, and the trigger probability of a photon detection is expressed as follows:

[0030] P=1-(1-P0) n

[0031] Where n is the number of effective pixels receiving photons. The probability of the pixel array receiving photons will increase with the increase of laser power. In this way, the amount of data that the counter / time digital converter 300 needs to process will increase under the condition of the same detection effect. However, due to the limited data processing capacity of the counter / time digital converter 300, Figure 2 As shown in (a) and (b), an error of Δt will be caused, resulting in the occurrence of pile-up distortion. The number of effective pixels n receiving photons is adjusted, thereby changing the probability of the effective pixel array receiving photons to adjust the current counting rate R of the counter / time digital converter 300, so that the current counting rate R of the counter / time digital converter 300 is at the maximum counting rate threshold R max and the minimum count rate threshold R min Within this appropriate range, the accuracy of ranging is improved, ensuring detection efficiency while reducing power consumption.

[0032] The enable control module 500 is used to generate an enable for adjusting the number n of effective pixels receiving photons according to the comparison result and output it to the pixel array module 100 , that is, the enable control module 500 outputs a control signal to adjust the number of effective SPADs.

[0033] Further, the comparison result includes: a first comparison result and a second comparison result;

[0034] The counting rate comparison and judgment module 400 is also used to compare the current counting rate R with the maximum counting rate threshold R max Compare, if R>R max , then the first comparison result is output to the enabling control module 500; until R <R max , and then compare the current counting rate R with the minimum counting rate threshold R min Compare, if R <R min , then the second comparison result is output to the enabling control module 500 until R>R min When , the comparison ends.

[0035] The enable control module 500 is further configured to generate an enable for reducing the number n of effective pixels receiving photons according to the first comparison result and output it to the pixel array module 100, or

[0036] An enable for increasing the number n of effective pixels receiving photons is generated according to the second comparison result and output to the pixel array module 100 .

[0037] See also Figure 3 , Figure 3 The working flow diagram of a digital silicon photomultiplier tube provided by the embodiment of the present invention is as follows:

[0038] In a laser detection operation, the maximum counting rate threshold R of the counter / time digital converter 300 is first set according to the laser power. max and the minimum count rate threshold R min After emitting laser to the target, a digital silicon photomultiplier tube of the present invention starts to work. First, the pixel array module 100 receives the photons in the laser echo in the field of view. The SPAD device in the pixel is triggered to generate photocurrent. After passing through its front-end circuit, a voltage pulse signal is generated and input to the logic circuit module 200. The voltage pulse signal is integrated and then input to the counter / time digital converter 300 to count the voltage pulse signal. During the counting process, the current counting rate R is fed back to the counting rate comparison judgment module 400 and compared with the maximum counting threshold R. max Compare, if R>R max , the first comparison result is output to the enabling control module 500, and the enabling control module 500 controls the pixel array module 100 to reduce the number n of effective pixels receiving photons, so as to reduce the probability of the pixel array receiving photons, thereby reducing the current counting rate R, until R <R max Then the current counting rate R is compared with the minimum counting rate threshold R min Compare, if R <R min , the second comparison result is output to the enabling control module 500, and the enabling control module 500 controls the pixel array module 100 to increase the number n of effective pixels receiving photons, so as to increase the probability of the pixel array receiving photons, thereby increasing the current counting rate R, until R>R min The comparison and judgment of the counting rate is then ended. The above process is continuously carried out during the receiving process to ensure that the counting rate R is always maintained at R min <R<R max The purpose of improving ranging accuracy and reducing power consumption is achieved within the range.

[0039] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0043] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0044] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A digital silicon photomultiplier tube, characterized in that: include: A pixel array module (100), a logic circuit module (200), a counter / time digital converter (300), a counting rate comparison and judgment module (400), and an enabling control module (500); The feedback input end of the pixel array module (100) is connected to the output end of the enable control module (500), and the output end of the pixel array module (100) is connected to the input end of the logic circuit module (200); the pixel array module (100) is used to receive photons in the laser echo within the field of view and generate a voltage pulse signal to output to the logic circuit module (200); The output end of the logic circuit module (200) is connected to the input end of the counter / time digital converter (300); the logic circuit module (200) is used to output the voltage pulse signal to the counter / time digital converter (300) for counting; The feedback output terminal of the counter / time digital converter (300) is connected to the input terminal of the counting rate comparison and judgment module (400); the counter / time digital converter (300) is used to count the voltage pulse signal, convert the counting result into a digital signal and output it from the OUT terminal, and transmit the information of the current counting rate R to the counting rate comparison and judgment module (400) through the feedback output terminal; The output end of the counting rate comparison and judgment module (400) is connected to the input end of the enabling control module (500); the counting rate comparison and judgment module (400) is used to compare the current counting rate R with the maximum counting rate threshold R max and the minimum count rate threshold R min Performing a comparison, and outputting the comparison result to an enabling control module (500); The enable control module (500) is used to generate an enable for adjusting the number n of effective pixels receiving photons according to the comparison result and output it to the pixel array module (100).

2. A digital silicon photomultiplier tube according to claim 1, characterized in that: The comparison result includes: a first comparison result and a second comparison result; The counting rate comparison and judgment module (400) is also used to compare the current counting rate R with the maximum counting rate threshold R max Compare, if R>R max , then output the first comparison result to the enabling control module (500); If R <R max , then the current counting rate R and the minimum counting rate threshold R min Compare, if R <R min , then the second comparison result is output to the enabling control module (500). When R>R min When , the comparison ends; The enable control module (500) is further used to generate an enable for reducing the number n of effective pixels receiving photons according to the first comparison result and output it to the pixel array module (100), or An enable for increasing the number n of effective pixels receiving photons is generated according to the second comparison result and output to the pixel array module (100).

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