LiDAR receiver circuit for receiving optical signals via photodetectors

Abstract

A laser radar receiver circuit is used to receive optical signals through photodetectors to detect events or objects in its surrounding area. It has redundancy of the receiver circuit to reduce the probability of failure. It includes a photodetector array with multiple photodetectors for receiving optical signals and outputting measurement signals, and the photodetectors are arranged in a two-dimensional matrix in the form of multiple rows and n columns; multiple receiver circuits for receiving measurement signals; m multiplexers, which are electrically connected between the photodetector array and the receiver circuit, and the number m is greater than 1; at least one multiplexer is connected to a column of photodetectors and at least two receiver circuits; each receiver circuit receives and processes the measurement signals of a column of photodetectors; a column of photodetectors is assigned to each receiver circuit by default; the multiplexer connects the column of photodetectors to receiver circuits other than the receiver circuit, which is assigned to the column of photodetectors by default.

Description

Technical Field

[0001] The invention relates to a laser radar receiver circuit for receiving an optical signal by means of a photodetector in order to detect an event or an object in a surrounding area of ​​the laser radar receiver circuit. The laser radar receiver circuit has redundancy of the receiver circuit for reducing the probability of failure. It comprises a photodetector array having a plurality of photodetectors for receiving the optical signal and for outputting a measurement signal. The photodetectors are arranged in a two-dimensional matrix in the form of rows and columns. Background Art

[0002] Lidar receiver circuits and Lidar sensors (Lidar: Light Detection and Ranging) are optical sensors that are used in many applications in order to detect the surrounding area of ​​the sensor and ultimately evaluate it. For example, Lidar sensors are used in vehicles in order to detect the surrounding area of ​​the vehicle and perform corresponding adjustments of the components of the vehicle. For example, Lidar sensors can be used when distance measurements are to be made to the vehicle in front. Sensors of this type are also used in the case of autonomous or partially autonomous driving of vehicles, during which independent and automatic deceleration, steering and acceleration of the vehicle are possible. It is thus necessary to detect the surrounding area directly in front of the vehicle as well as the lateral areas around the vehicle. In the case of detecting individual events, the method of direct time-of-flight measurement is therefore often used. Then, by forming a histogram, a picture can be formed from the individual events about what the surrounding area of ​​the vehicle looks like and whether objects are located in the vicinity of the vehicle.

[0003] Lidar receiver circuits and lidar sensors usually include a plurality of photodetectors or photodiodes arranged in the form of a matrix. In the automotive sector, arrays are usually used that have more than 160×50 photodetectors or sensors. The lidar sensor additionally includes a memory with a plurality of transistors. In the case of a lidar sensor with approximately 260×80 pixels or photodetectors, respectively, the number is approximately 5.6 million transistors.

[0004] Despite careful production under the best conditions and in clean rooms, failures of individual transistors can occur during production, which limit the functionality of the LiDAR sensor or render the entire sensor useless. Therefore, during the implementation of a memory without redundancy, there is a high probability of yield loss (i.e., failure of individual transistors), which renders the sensor useless.

[0005] Despite the continued advancements in the development of LiDAR sensors, there remains a high demand for improvements in these sensors, particularly in reducing the probability of failure and yield loss during production. Summary of the invention

[0006] This object is achieved by a lidar receiver circuit for receiving optical signals via a photodetector having the features of claim 1 , by a lidar receiver system having the features of claim 14 , and by a method having the features of claim 16 .

[0007] It has been determined in the context of the present invention that the addition of redundancy is generally an effective means for reducing yield loss. However, redundancy of transistors or memory cells leads to the problem that a strongly parallelized structure then has lines of different lengths between components and leads to flight time differences, which makes it impossible to use the circuit, or reduces the processing speed in a way that it cannot be used in practice.

[0008] In one aspect, the invention relates to a laser radar receiver circuit for receiving optical signals by means of photodetectors in order to detect events and objects in the surrounding area of ​​the laser radar circuit. The laser radar receiver circuit has redundancy of the receiver circuit for reducing the probability of failure. It comprises a photodetector array with a plurality of photodetectors for receiving the optical signals and for outputting a measurement signal. The photodetectors are arranged in a two-dimensional matrix in the form of a plurality of rows and n columns, wherein the number n is greater than 1, i.e. the matrix has at least two columns.

[0009] The laser radar receiver circuit comprises i multiple receiver circuits for receiving measurement signals of the photodetectors, wherein the number i is greater than n. The circuit has m multiplexers, which are electrically arranged between the photodetector array and the receiver circuits and are connected to the photodetectors and the receiver circuits. The number m is thus greater than 1; preferably m=n.

[0010] At least one of the multiplexers is connected to a column of photodetectors and at least two receiver circuits. Each receiver circuit is configured to receive and process a measurement signal of a column of photodetectors. By default, a column of photodetectors is assigned to each receiver circuit. The multiplexer is configured to connect a column of photodetectors to a receiver circuit other than the receiver circuit that is assigned to the column of photodetectors by default.

[0011] Thus, the multiplexer can assign a column of photodetectors to two different, preferably adjacent, receiver circuits by corresponding interconnections and can connect the column of photodetectors to one of the assigned receiver circuits. When a receiver circuit fails, which can be determined in production by means of a measurement method and a measurement program that is run by default, the multiplexer can be switched so that the column of photodetectors provided by default for the defective receiver is interconnected with the adjacent receiver circuit. Due to the matrix-shaped arrangement of the photodetectors and the parallelized arrangement of the receiver circuits, the line path changes only very slightly or even not at all during the switching of the multiplexer from a receiver circuit to an adjacent receiver circuit. Therefore, changes in the flight time do not actually occur or are negligible. Therefore, when a receiver unit fails and the multiplexer switches to another receiver circuit, no distortion occurs during the flight time measurement.

[0012] Thus, the paths to the redundant receiver circuit (which may be an SRAM block, for example) and its equally redundant control block including an asynchronous timestamp latch can be kept as short as possible. In particular, the nominal connections between the columns of photodetectors to the multiplexers and from the multiplexers to the receiver circuits connected to the multiplexers can be designed identically for all channels in the layout of the lidar receiver circuit. Even during a failure of another connection to an adjacent receiver circuit or during switching in the multiplexer, a change in the flight time does not occur in this way.

[0013] In another aspect, the invention relates to a lidar receiver system comprising a lidar receiver circuit as described herein and comprising a test circuit configured to contact all receiver circuits and perform predetermined tests in order to detect defects in the receiver circuits.

[0014] Based on the detection of a defect in a receiver circuit, the connected multiplexer can be controlled so that it activates the connection to an adjacent receiver circuit also connected to the multiplexer and directs the signal from the column of photodetectors assigned to the multiplexer to another receiver circuit without the defect.

[0015] In another aspect, the invention relates to a lidar receiver circuit, as just described, which additionally comprises a light source for emitting optical radiation in the visible or invisible range, which optical radiation is detectable by a photodetector. The lidar receiver system is configured in such a way that the emitted optical radiation reflected by objects in or near the surrounding area of ​​the lidar receiver system is detected by at least one of the photodetectors of the photodetector array and processed in at least one of the receiver circuits.

[0016] Further aspects of the invention relate to a corresponding method and a computer program product having a program code for performing the steps of the method when the program code runs on a computer, as well as a storage medium on which the computer program is stored, which enables the execution of the method described herein when the computer program runs on a computer.

[0017] According to another aspect, the invention relates to a lidar receiver comprising a lidar receiver circuit as described herein and defined in the claims, or to a lidar system.

[0018] Another aspect of the invention relates to a vehicle comprising a lidar system or a lidar receiver system comprising a lidar receiver circuit as defined in the claims and described herein.

[0019] Preferred embodiments of the invention are described in the dependent claims. It goes without saying that the features mentioned above and those to be described below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the invention. The method and the computer program product can be configured in particular according to the embodiments described for the device in the dependent claims.

[0020] In a preferred embodiment of the laser radar receiver circuit, the receiver circuits are independent of each other. Each receiver circuit works independently and is not affected by adjacent circuits.

[0021] In a preferred embodiment, asynchronous processing of the measurement signal occurs in the independent receiver circuits. Therefore, the receiver circuits are not dependent on a common clock signal. As soon as the measurement signal is applied to the receiver circuit, each receiver circuit operates. Synchronization by a system clock is not necessary.

[0022] A preferred embodiment of the laser radar receiver circuit provides that if there is already a connection of a default assigned receiver circuit to another column of photodetectors, one of the multiplexers connects a column of photodetectors to a receiver circuit other than the default assigned receiver circuit. By using several multiplexers connected to at least two, preferably three or four, preferably adjacent receiver circuits, the receiver circuit communicates with two or three, or four multiplexers respectively. When a receiver circuit fails, the multiplexer is allocated in such a way that the effective connection through which the measurement signal can be transmitted between the multiplexer and the receiver circuit is replaced by a new effective connection. When a receiver circuit fails, several multiplexers may therefore be required to reactivate the already existing connection to the receiver circuit, or the effective connection must be switched respectively in order to establish a new connection. This may be necessary in order to ensure that only one column of photodetectors is allocated to each receiver circuit and that each receiver circuit processes only the measurement signal from one column of photodetectors. When a receiver circuit fails, the 1:1 allocation of multiplexers to receiver circuits is still maintained.

[0023] A preferred embodiment of the lidar receiver circuit is configured in such a way that when a defect of one of the receiver circuits is detected, the corresponding multiplexer connects the corresponding column of photodetectors to another receiver circuit. The multiplexer is preferably connected to a receiver circuit for which a connection to the column with photodetectors does not yet exist. Otherwise, a new assignment must also be made for the newly selected receiver circuit by means of another multiplexer.

[0024] In a preferred embodiment of the receiver circuit, when a (first) defect of the qth receiver circuit is detected, the corresponding qth multiplexer will connect the qth column of photodetectors to a receiver circuit reduced by 1 (the q-1th receiver circuit). All first to q-1th multiplexers change the assignment between the columns of photodetectors and the receiver circuits according to the same principle. This process is preferably performed for all q less than or equal to m / 2. Thus q and m are natural numbers; m is the number of multiplexers.

[0025] Such switching of the multiplexers is therefore preferably performed for the multiplexers in a row of receiver circuits or the first half of the receiver circuits, respectively.

[0026] Therefore, this interconnection preferably occurs when a defect is detected in the first half of the receiver circuit.

[0027] In other words: when a defect of the qth receiver circuit is detected, the corresponding qth multiplexer connects the qth column of the photodetector to the receiver circuit reduced by 1, and all 1 to q-1th multiplexers, preferably arranged in a fixed order, and the r-1th receiver circuit are connected to the r+1th column of the photodetector. The assignment between the columns and the receiver circuits is changed or established according to the same principle. Thus r is a natural number. Therefore, the assignment of the photodetector column increased by 1 to the next lower receiver circuit occurs.

[0028] If a further defect of one receiver circuit is detected, for example a defect of the qth receiver circuit, the corresponding qth multiplexer switches the qth column of the photodetector with a receiver circuit (q+1) increased by 1 and connects it. The same happens for all q+1th to mth multiplexers, which are preferably arranged in a fixed order, which connect the r+1th receiver circuit to the r-1th column of the photodetector. The assignment between columns and receiver circuits occurs according to the same principle and the connections are established so that this preferably applies to all q greater than or equal to m / 2, where q and r and m are natural numbers and m represents the total number of multiplexers.

[0029] The number i of receiver circuits in the lidar receiver circuit is particularly preferably greater than the number m of multiplexers. i is preferably greater than or equal to m+2, which means that the number of receivers is greater than the number of multiplexers by 2 or more. Particularly preferably, i is greater than or equal to m+3, so that the number of receiver circuits is at least 3 greater than the number of multiplexers. Thus, redundancy is provided in such a way that two additional receiver circuits or three additional receiver circuits, respectively, are provided in the lidar receiver circuit and two or three receiver circuits, respectively, can be defective without having to take the lidar receiver circuit out of service.

[0030] In a preferred embodiment, at least one of the multiplexers or multiplexers used in the lidar receiver circuit is a 1:x multiplexer, respectively. A column of photodetectors can then be connected to x receiver circuits via the multiplexer. x-1 is thus equal to the difference between the number of receiver circuits i and the number of columns of photodetectors n. Preferably, x=3, particularly preferably, x=5.

[0031] In a preferred embodiment of the laser radar receiver circuit, the number of multiplexers m is equal to the number of columns of photodetectors n. Thus, one multiplexer is assigned to each column of photodetectors.

[0032] A specific embodiment of the lidar receiver circuit provides that the receiver circuit is a TDC circuit, ie a time to digital conversion circuit.

[0033] The receiver circuit of the lidar receiver circuit preferably comprises a memory unit, which particularly preferably has an SRAM memory. It is also preferred that the receiver circuit comprises a histogram memory in order to form a histogram of the optical events and to be able to draw conclusions about objects in the vicinity of the lidar receiver circuit from the number of optical events that occur.

[0034] A preferred embodiment of the lidar receiver circuit provides that the photodetector comprises a photodiode, preferably an avalanche diode. In a highly preferred embodiment, the photodetector comprises a single photon avalanche diode (SPAD). The photodetector additionally comprises a readout circuit.

[0035] According to a preferred embodiment of the laser radar receiver circuit, it comprises a shift register, wherein the setting of the multiplexer is stored in the shift register. A default assignment of a column of photodetectors to receiver circuits is preferably stored in the shift register, particularly preferably additionally or alternatively, a current assignment of a column of photodetectors to receiver circuits is stored in the shift register.

[0036] The method according to the invention for bypassing a defective receiver circuit of a lidar receiver circuit configured for receiving optical signals by means of photodetectors and for detecting objects in the surrounding area of ​​the circuit comprises the following steps: The generation of a default allocation of ix receiver circuits of n columns of photodetectors to m multiplexers occurs in a first step. It is thus applicable that m=in. In other words, the number i of receiver circuits is x times the number of columns of photodetectors. However, by this step, a column of photodetectors is only allocated to as many receiver circuits as there are columns of photodetectors. The redundant receiver circuits do not undergo an allocation. Nevertheless, just like all other receiver circuits, the redundant receiver circuits are also connected to at least one multiplexer.

[0037] In a further step, a defect of the qth receiver circuit is detected.

[0038] In the assignment step, the qth column of the current photodetector is assigned to another receiver circuit by means of the qth multiplexer. The default assignment of the photodetector columns to the receiver circuits is thus canceled and a new assignment is performed by means of the corresponding (assigned) multiplexer. This occurs in the case of a defective first receiver circuit, in which the 1st to qth columns of the photodetector were assigned to the corresponding previous receiver circuit, thus here the q-1th receiver circuit.

[0039] In a preferred embodiment of the method, the qth to nth columns of photodetectors are assigned to the respective following (q+1th) receiver circuits in case another receiver circuit has an additional defect. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention will be described and explained in more detail below based on some selected exemplary embodiments in conjunction with the accompanying drawings, in which:

[0041] Figure 1 A laser radar receiver circuit with a photodetector array according to the present invention is shown;

[0042] Figure 2 Details are shown from Figure 1 A photodetector array;

[0043] Figure 3 Shows that according to Figure 1 A schematic diagram of a lidar receiver system of a lidar receiver circuit;

[0044] Figure 4 Additional embodiments of lidar receiver circuits are shown;

[0045] Figure 5 A schematic diagram of a vehicle having a laser radar receiver circuit according to the present invention is shown;

[0046] Figure 6 shows a method for bypassing Figure 1 A general flow chart of a method for repairing a defective receiver circuit of a lidar receiver circuit. DETAILED DESCRIPTION

[0047] The accompanying drawings show a laser radar receiver circuit 10 in different embodiments. Figure 1 The lidar receiver circuit 10 according to the invention comprises a photodetector array 20 having a plurality of photodetectors 22, a plurality of receiver circuits 30 and a plurality of multiplexers 40, wherein the multiplexers 40 are connected between the photodetector array 20 and the receiver circuits 30 and establish a connection between the photodetector array 20 and the receiver circuits 30 in each case.

[0048] exist Figure 2Detailed description is given in FIG. 1 of the accompanying drawings. The photodetector array 20 is shown in detail in FIG. It comprises a plurality of photodetectors 22 for receiving optical signals and for outputting measurement signals. The photodetectors 22 are arranged in a two-dimensional matrix. They are thereby arranged in a plurality of rows and n columns 24 in the photodetector array 20. At least two columns 24 of more than one photodetector 22 each exist. A preferred embodiment provides more than 100 columns 24 of photodetectors 22, preferably more than 150 columns, more preferably more than 200 columns, and highly preferably more than 250 columns. A preferred embodiment of the photodetector array 20 for a lidar circuit has, for example, 256 or 258 columns 24 of photodetectors. Each column 24 preferably comprises more than 10, highly preferably more than 50, particularly preferably 80 photodetectors 22. A photodetector array 20 can thereby be constructed that can receive and process a plurality of signals.

[0049] According to Figure 2 In the specific embodiment shown in , the photodetector 22 may include, for example, a photodiode 26, which is preferably an avalanche diode, and particularly preferably a single photon avalanche diode (SPAD). The photodetector 22 may also include a readout circuit 28 to convert the optical signal recorded by the photodiode 26 into an electrical measurement signal. Other embodiments of the photodetector 22 are conceivable.

[0050] Figure 3 A lidar receiver system is shown that includes a lidar receiver circuit 10 and a test circuit 52 that is configured to contact a receiver circuit 30 of the lidar receiver circuit 10 and perform predetermined or specified tests to detect defects in the receiver circuit 30 .

[0051] Figure 3 A particular embodiment of a laser radar receiver system 50 is shown in FIG. 5 , which further comprises a light source 54 that preferably emits an electromagnetic or optical signal or a light signal in the visible or invisible range. The light source 54 is preferably a laser light source or an infrared light source.

[0052] Preferred optical radiation from the light source 54 is emitted by the system and reflected off objects in the vicinity or surrounding area of ​​the lidar receiver system 50. The reflected radiation is received and detected by at least one of the photodetectors 22 of the lidar receiver circuit 10 and processed in at least one of the receiver circuits 30.

[0053] The lidar receiver circuit 10 according to the present invention is preferably constructed in such a way that it has redundancy of the receiver circuits 30 in order to reduce the probability of failure of the receiver circuit as a whole. The number of receiver circuits 30 is thus greater than the number of columns 24 of photodetectors 22 in the photodetector array 20 of the lidar receiver circuit 10. The number i of receiver circuits 30 is preferably greater than the number of columns 24 of photodetectors 22 by at least two, particularly preferably greater than at least four.

[0054] The number m of multiplexers electrically arranged between the photodetector array 20 and connected to the columns 24 of the photodetector array 20 and the receiver circuit 30 is greater than 1. The number m of multiplexers 40 is preferably equal to the number n of columns 24 of the photodetectors 22 .

[0055] The lidar receiver circuit 10 is configured in such a way that one multiplexer 40 is connected to at least two, preferably at least three, receiver circuits 30 and can in each case contact one of the receiver circuits 30. In this sense, "contact" means that the electrical connection is activated so that an electrical signal is transmitted from a column 24 of photodetectors 22 to one receiver circuit 30.

[0056] Figure 4 An embodiment of a lidar receiver circuit 10 is shown, in the case of which the photodetector array 20 is arranged in the center of the circuit. Receiver circuits 30 and multiplexers 40 are arranged in each case on the upper edge and on the lower edge. The total number of receiver circuits 30 and multiplexers 40 is thus divided in half, so that half of the receiver circuits 30 and multiplexers 40 are arranged above the photodetector array 20 and the other half are arranged below the photodetector array 20.

[0057] The embodiment illustrated here shows a photodetector array 20 comprising a total of 258 columns 24 , each column comprising 80 photodetectors 22 .

[0058] The odd-numbered columns 24 are connected to multiplexers 40 above the array. The even-numbered columns 24 of the photodetector array 20 are connected to even-numbered multiplexers 40 below the array, such as Figure 4 as shown in .

[0059] In the embodiment shown here, a total of four more receiver circuits 30 are provided than columns 24. In the group of odd-numbered receiver circuits 30 and odd-numbered multiplexers 40 arranged above the photodetector array 20, there are therefore two more receiver circuits 30 than multiplexers 40. For example, the column 24 with number 259 is connected to the multiplexer 40 with number 259. The 259th multiplexer 40 is in turn connected to three receiver circuits 30, namely those with numbers 257, 259 and 261. By default, the 259th multiplexer is connected to the 259th receiver circuit 30. This means that the signal from the 259th column 24 of the photodetector 22, in particular the measurement signal, is conveyed to the 259th multiplexer and from there to the 259th receiver circuit 30, as shown in FIG. Figure 4 259th multiplexer 40 can, however, also optionally transmit the measurement signal received from the 259th column 24 to the 257th or 261st receiver circuit 30. This occurs, for example, when the 259th receiver circuit 30 is detected as defective in the test. Thus, the test performed by the test circuit 52 can be used as a basis.

[0060] This switching similarly applies to the even-numbered columns 24 , multiplexers 40 , and receiver circuits 30 arranged below the photodetector array 20 .

[0061] In the event that the qth receiver circuit 30 (e.g., the receiver circuit 30 numbered 259) fails, the corresponding qth (259th) multiplexer 40 will connect the qth column 24 of the photodetector 22 to a receiver circuit other than the qth receiver circuit 30, i.e., to the q-1th or q+1th receiver circuit 30.

[0062] When a defect occurs at a receiver circuit 30 arranged in the first half of the corresponding group of receiver circuits 30, the qth multiplexer 40 is preferably interconnected with the q-1th receiver circuit 30. In the case of an odd-numbered receiver circuit 30, then the defect of the receiver circuit 30 will also be within the 3rd to 129th receiver circuits 30. If a receiver circuit 30 is detected in the second half of the group of receiver circuits 30, i.e., in the half of the receiver circuits 30 with higher odd numbers, then the qth multiplexer 40 will connect the qth column 24 to the q+1th receiver circuit 30.

[0063] It goes without saying that it is also possible to always select the receiver circuit 30 with the next smaller number, or always select the receiver circuit 30 with the next larger number. For example, this can also depend on whether a defective receiver circuit 30 has been detected in the first half of the receiver circuits 30. If no defective receiver circuit 30 is detected, the multiplexer 40 can also initially control the next larger receiver circuit 30 in the first half of the receiver circuits 30.

[0064] When deviating from the default assignment of multiplexers 40 to receiver circuits 30 upon detection of a defective receiver circuit 30 , the assignments of all other multiplexers 40 to respective receiver circuits 30 also need to be optionally changed accordingly.

[0065] For example, if the receiver circuit 30 with number 3 is detected as defective, the assignment between the multiplexer 40 with number 3 and the receiver circuit 30 with number 3 is canceled. Instead, a connection is established between the multiplexer 40 with number 3 and the receiver circuit 30 with number 1. All other assignments between the multiplexer 40 and the receiver circuit 30 then remain unaffected. In the event that the penultimate receiver circuit 30 (e.g., the receiver circuit 30 with number 259) is defective, all other assignments between the multiplexer 40 and the receiver circuit 30 also remain unaffected. However, if, for example, the receiver circuit 30 with number 257 is detected as defective, the multiplexer 257 establishes a connection to the receiver circuit 30 with number 259. The multiplexer 40 with number 259 then has to establish an assignment to the receiver circuit 30 with number 261 accordingly.

[0066] Due to the changed allocation, lidar receiver circuits 10 can therefore also be used and delivered which include one or two defective receiver circuits 30. The number of tolerable defective receiver circuits 30 depends on the number of redundancies; in other words, it depends on how many more receiver circuits 30 there are than multiplexers 40.

[0067] In such Figure 4 In the preferred embodiment shown in FIG. 1 , the laser radar receiver circuit 10 comprises a shift register 12, which is illustrated here in a dashed manner. The assignment between the multiplexer 40 and the receiver circuit 30 is stored in the shift register 12. A default assignment is thereby initially stored. However, in the event of a detected defect, a changed and new assignment is stored. A rewriting of the values ​​in the shift register can thus occur.

[0068] exist Figure 4As can be seen in FIG. 3 , the receiver circuit 30 preferably includes a time-to-digital conversion circuit, i.e., a TDC circuit 32. The receiver circuit 30 preferably also includes a memory unit 34, which is preferably an SRAM memory. Additionally or alternatively, the receiver circuit 30 may also include a histogram memory in order to form a histogram, i.e., collect (e.g., accumulate) the optical signals detected by the photodetector 22.

[0069] Figure 4 The embodiment shown in has the following advantages: despite the redundant receiver circuit 30, the line length remains almost the same even in the case of non-standard interconnection of the multiplexer 40 and the receiver circuit 30. Therefore, in a practical system, the flight time difference that may occur is negligible. Due to the massively parallelized structure, distortion of the flight time measurement does not occur. This is a requirement, for example, imposed by a control block including an asynchronous timestamp, in which case the line to the redundant SRAM block (receiver circuit) must be kept as short as possible. Despite the redundant form of the lidar receiver circuit 10, the nominal connection (i.e., the default connection between the photodetector 22 and the receiver circuit 30) is designed identically for all channels in the layout. Additional receiver circuits 30 on the outer edges of the rows of receiver circuits 30 are provided as redundant receiver circuits 30. The number of redundant blocks can be designed arbitrarily.

[0070] Due to the arrangement with two sets of receiver circuits 30 and multiplexers 40, for example above and below the photodetector array 20, as Figure 4 As shown in , two subsystems can be provided, each with two redundant receiver circuits 30. In the subsystem of even-numbered receiver circuits, these are the receiver circuits with numbers 0 and 260, and in the subsystem or group of odd-numbered receiver circuits 30, these are the circuits with numbers 1 and 261, respectively. In the case of two redundant receiver circuits 30 (that is, two additional receiver circuits 30 that are not used under normal circumstances), for each group or subsystem, a 3:1 multiplexer 40 is then provided between the columns 24 of the photodetectors 22 and the receiver circuits 30. Thus, the multiplexer 40 can contact the directly assigned receiver circuit 30 or the circuits adjacent to the left and right, respectively, and can establish connections to them.

[0071] With this arrangement, for example Figure 4As shown in , in each of the two groups or subsystems, each subsystem can shield up to two defective receiver circuits, respectively, because the multiplexer 40 is configured accordingly so that between the two defective blocks (receiver circuits), the nominal receiver circuit 30 (SRAM block) is assigned to the photodetector column. On the left side of the left block, all left neighbors of the nominal receiver circuit are assigned to the photodetector column. On the right side of the defective receiver circuit (block) on the right, all right neighbors of the nominal receiver circuit are assigned to the photodetector column. In this way, in the event of a defect, the blocks or receiver circuits 30 that are not defective are replaced by blocks or receiver circuits that are clearly redundant, respectively, which will result in significantly different distances and assignments to the columns 24 of the photodetectors. Instead, multiple functional and contributing receiver circuits 30 (SRAM blocks) are shifted in their assignment.

[0072] It is thereby ensured that the difference in the distance of the connection or line between the column 24 of the photodetector 22 and the receiver circuit 30, in particular the memory cell 34, is negligible and that the distance is not greater than the other distances to other receiver circuits 30. This is particularly important when using time stamps. The multiplexing before the synchronous SRAM control of the memory cell 34 has the great advantage that the interface here consists of only two signals per column 24 of the photodetector 22, namely the asynchronous trigger input and the reset of the corresponding column 24 at the end of each SRAM access, in order to actively end the dead time and in order to be sensitive to the next optical signal in the photodetector 22 or in the corresponding column 24, respectively. The SRAM control of the receiver circuit and the reset of the photodetector 22 of the corresponding column 24 are jointly created in the circuit.

[0073] Using the methods described here and in Figure 4 In the particular embodiment shown in the architecture, the yield loss during production is greatly improved. Figure 4 The arrangement of and two redundant receiver circuits 30 in two groups of receiver circuits 30 (above and below the photodetector array 20) results in a significant increase in the reliability of the system.

[0074] If the probability of an individual error in the entire Lidar receiver circuit 10 is p, then this is the probability of failure of the entire circuit. The production yield without redundancy then results in v=1-p.

[0075] The probability of failure in one half of the receiver circuit 30 without redundancy is p / 2. The probability of failure in one half of the receiver circuit 30 with two times redundancy is (p / 2) 3 . Failure occurs only in the case of three errors. In this case, the failure probability of the entire lidar receiver circuit 10 is 2×2 times the redundancy and is therefore equal to p r=2×(p / 2) 3 .

[0076] This results in a production yield of v without redundancy r =1-p r =1-2×(p / 2) 3 .

[0077] When assuming a 50% probability of failure, a 50% production yield is produced without redundancy, but a 97% production yield is produced with redundancy.

[0078] Without redundancy, a failure probability equal to 10% results in a production yield equal to 90%, while with redundancy, it results in a production yield equal to 99.975%.

[0079] Even for significantly low error probabilities, redundancy still works:

[0080] A failure probability p equal to 75% results in a production yield equal to 25% without redundancy and equal to 89.5% with redundancy.

[0081] If the error probability is in fact this high, greater redundancy would solve this problem, such as four redundant receiver circuits 30 per half of the receiver circuits 30 (i.e., per group (subsystem) of receiver circuits 30). In this case, the failure probability is calculated as p r =2×(p / 2) 5 ; Only the fifth error causes failure of the entire lidar receiver circuit 10.

[0082] With an error probability of 75%, this results in a production yield of 25% with no redundancy and a production yield of 98.5% with 2×4 redundancy.

[0083] Therefore, redundancy is an effective means for significantly reducing yield loss. By the arrangement and embodiments proposed here, even in the event of a failure of the receiver circuit 30, the connection paths to the redundant receiver circuit 30 can have almost the same length. This means that the connection paths between the photodetector 22 and the receiver circuit 30 have the same length for all connections, so that they have no effect and are negligible in practice.

[0084] Figure 5 A vehicle 60 is shown including a laser radar system including a laser radar system according to Figure 1 or according to Figure 4 A lidar receiver circuit 10 is provided.

[0085] Figure 6Schematically illustrates a process sequence for reducing yield loss during the production of a LiDAR receiver circuit 10 for receiving optical signals via a photodetector 22 in order to detect events or objects in the surrounding area of ​​the LiDAR receiver circuit 10. The LiDAR receiver circuit 10 is preferably based on Figures 1 to 4 The method ensures that in the presence of redundancy of the receiver circuits 30, a lidar receiver circuit 10 can be produced which operates properly even in the event of failures of a specified, acceptable number of receiver circuits 30 and that falsification in time-of-flight measurements is excluded despite the redundancy, in particular in the case of time-critical, asynchronous timestamps or time signals.

[0086] In a first step S10 of generating a default assignment, n columns 24 of the photodetector 22 are assigned to ix receiver circuits 30 by means of m multiplexers 40. It thus applies that in=x, where i is the number of all receiver circuits 30, x is the number of redundant receiver circuits 30, and n is the number of columns 24 of the photodetector 22.

[0087] In a further step S12 of detecting a defect, a defect is detected in a receiver circuit, for example in the qth receiver circuit 30. This is followed by a step S14 of assigning the current qth column 24 of the photodetector 22 to another receiver circuit 30 via the qth multiplexer 40. When a defect is detected, the default assignment between the columns 24 of the photodetector 22 and the receiver circuits 30 is thus cancelled, so that the qth column 24 is assigned to a receiver circuit other than the qth receiver circuit 30 via the qth multiplexer 40, thus to the wth receiver circuit 30, whereby q does not equal w. Preferably, w=q±1.

[0088] According to the method, in case of a defect in the first receiver circuit 30, the 1st to qth columns 24 of the photodetector 22 are assigned to the corresponding preceding receiver circuits 30, thus to the q-1th receiver circuit 30. In case of the first defect, since the first receiver circuit 30 is a redundant receiver circuit 30 and is not assigned to a column 24 of the photodetector 22 by default, an assignment to an adjacent receiver circuit 30, i.e., to a preceding receiver circuit 30, occurs.

[0089] When a second defect of a receiver circuit 30, i.e., a second defective receiver circuit 30, is detected, the qth to nth columns 24 of the photodetector 22 may preferably be assigned to the corresponding subsequent receiver circuit 30, i.e., the q+1th receiver circuit 30. Thus, it occurs that the qth column 24 is assigned to the next higher receiver circuit 30. This is easily achieved because the last receiver circuit 30, i.e., the i-th receiver circuit 30, is a redundant circuit and is not assigned to any column 24 of the photodetector 22 by default.

[0090] The invention is fully described and explained based on the drawings and the description. The description and explanation should be understood as examples rather than limitations. The invention is not limited to the disclosed embodiments. Other embodiments or variations will be apparent to those skilled in the art when using the invention and during a careful analysis of the drawings, the disclosure and the following patent claims.

[0091] In the patent claims, the words "comprising" and "having" do not exclude the presence of further elements or steps. The indefinite article "a" or "an" does not exclude the presence of a plurality. The mere mention of some measures in several different dependent patent claims should not be interpreted as indicating that a combination of these measures cannot be used to advantage as well. Reference signs in the patent claims should not be understood as limitations.

Claims

1. A laser radar receiver circuit for receiving an optical signal via a photodetector (22) to detect an event or object in a surrounding area of ​​the laser radar receiver circuit (10), the laser radar receiver circuit having redundancy of a receiver circuit (30) for reducing the probability of failure, the laser radar receiver circuit comprising A photodetector array (20) having a plurality of photodetectors (22) for receiving optical signals and for outputting measurement signals, wherein the photodetectors (22) are arranged in a two-dimensional matrix in the form of a plurality of rows and n columns (24), wherein the number n is greater than 1; i receiver circuits (30) for receiving the measurement signal of the photodetector (22), wherein the number i is greater than n; m multiplexers (40) electrically arranged between the photodetector array (20) and the receiver circuit (30) and connected to the photodetector (22) and the receiver circuit (30), wherein the number m is greater than 1; in At least one of the multiplexers (40) is connected to a column (24) of photodetectors (22) and at least two receiver circuits (30); Each receiver circuit (30) is configured to receive and process measurement signals from a column (24) of photodetectors (22); By default, each receiver circuit (30) is assigned a column (24) of photodetectors (22); as well as A multiplexer (40) is configured to connect a column (24) of photodetectors (22) to a receiver circuit (30) different from the receiver circuit (30) assigned by default to the column (24) of photodetectors (22), wherein in the event of a receiver circuit failure the multiplexer is switched such that the column of photodetectors provided by default for the defective receiver is connected to an adjacent receiver circuit.

2. The laser radar receiver circuit according to claim 1, characterized in that: The receiver circuits (30) are independent of each other.

3. The laser radar receiver circuit according to claim 2, characterized in that: The measurement signal is processed asynchronously in the receiver circuit (30).

4. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: One of the multiplexers (40) connects a column (24) of photodetectors (22) to a receiver circuit different from the default assigned receiver circuit (30) under the condition that a connection of the default assigned receiver circuit to another column of photodetectors (22) already exists.

5. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: When a defect in one of the receiver circuits (30) is detected, the corresponding multiplexer (40) connects the corresponding column (24) of photodetectors (22) to another receiver circuit (30) for which no connection to a column (24) of photodetectors (22) exists.

6. The laser radar receiver circuit according to claim 5, characterized in that: For all q less than or equal to m / 2, when the first defect of the qth receiver circuit (30) is detected, the corresponding qth multiplexer (40) connects the qth column (24) of the photodetector (22) to the receiver circuit (30) reduced by one, and all the 1st to q-1th multiplexers (40) change or establish the allocation between the column (24) and the receiver circuit (30) according to the same principle, where q is a natural number.

7. The laser radar receiver circuit according to claim 6, characterized in that: For all q less than or equal to m / 2, when a second defect of the qth receiver circuit (30) is detected, the corresponding qth multiplexer (40) connects the qth column (24) of the photodetector (22) to the receiver circuit (30) increased by one, and all q+1th to mth multiplexers (40) arranged in a fixed order connect the r+1th receiver circuit (30) to the r-1th column (24) of the photodetector (22), where q and r are natural numbers.

8. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The number i of receiver circuits (30) is greater than the number m of multiplexers (40).

9. The laser radar receiver circuit according to claim 8, characterized in that: i is greater than or equal to m+2.

10. The laser radar receiver circuit according to claim 8, characterized in that: i is greater than or equal to m+3.

11. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The multiplexer (40) is a 1-to-x multiplexer (40) and is capable of connecting the columns (24) of the photodetectors (22) to x receiver circuits (30), where x-1 is equal to the difference between the number i of receiver circuits (30) and the number n of columns.

12. The laser radar receiver circuit according to claim 11, characterized in that: x is equal to 5.

13. The laser radar receiver circuit according to claim 11, characterized in that: x is equal to 3.

14. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The number m of multiplexers (40) is equal to the number n of columns (24) of photodetectors (22).

15. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The receiver circuit (30) includes a TDC circuit (32).

16. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The receiver circuit (30) includes a memory unit (34) and / or a histogram memory.

17. The laser radar receiver circuit according to claim 16, characterized in that: The memory unit (34) is a SRAM memory.

18. The laser radar receiver circuit according to any one of claims 1 to 3, characterized in that: The photodetector (22) includes a photodiode (26) and a readout circuit (28).

19. The laser radar receiver circuit according to claim 18, characterized in that: The photodiode (26) is an avalanche diode.

20. The laser radar receiver circuit according to claim 18, characterized in that: The photodiode (26) is a single photon avalanche diode.

21. The laser radar receiver circuit according to any one of claims 1 to 3, comprising a shift register (12), characterized in that: The settings of the multiplexer (40) are stored in the shift register (12).

22. The laser radar receiver circuit according to claim 21, characterized in that: A default assignment of columns (24) of photodetectors (22) to receiver circuits (30) is stored in the shift register (12), and additionally a current assignment of columns (24) of photodetectors (22) to receiver circuits (30) is stored in the shift register (12).

23. The laser radar receiver circuit according to claim 21, characterized in that: The current assignment of columns (24) of photodetectors (22) to receiver circuits (30) is stored in the shift register (12).

24. A lidar receiver system having a test circuit (52) and a lidar receiver circuit according to one of claims 1 to 23, wherein the test circuit (52) is configured to address all receiver circuits (30) and perform predetermined tests in order to detect defects in the receiver circuits.

25. The laser radar receiver system according to claim 24, comprising a light source (54) for emitting optical radiation in the visible or invisible range, which optical radiation can be detected by the photodetector (22), characterized in that Radiation reflected by objects in or near the surrounding area of ​​the lidar receiver system (50) is detected by at least one of the photodetectors (22) of the photodetector array (20) and processed in at least one of the receiver circuits (30).

26. A method for bypassing a defective receiver circuit (30) of a LiDAR receiver circuit according to one of claims 1 to 23, for receiving light signals by means of a photodetector in order to detect events or objects in a surrounding area of ​​the LiDAR receiver circuit, the method comprising the following steps: - establishing a default assignment of n columns (24) of photodetectors (22) to ix receiver circuits (30) using m multiplexers (40), where in=x applies; - detecting a defect in the qth receiver circuit (30); - assigning the current qth column (24) of the photodetector (22) to another receiver circuit (30) via a qth multiplexer (40); - wherein, in the event that a first receiver circuit (30) is defective, the 1st to qth columns (24) of the photodetectors (22) are assigned to the respectively preceding receiver circuits (30).

27. The method according to claim 26, characterized in that In the case where the receiver circuit (30) has a second defect, the qth to nth columns (24) of the photodetector (22) are allocated to the respective subsequent receiver circuits (30).

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