Remote indirect time-of-flight laser radar sensor integrated circuit
By employing current generation and signal processing modules in the long-range indirect time-of-flight lidar sensor integrated circuit, the problems of low signal-to-noise ratio and background light noise in traditional iToF lidar during long-range and high-precision detection are solved, achieving a high signal-to-noise ratio ranging effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-14
- Publication Date
- 2026-04-07
AI Technical Summary
Traditional iToF lidar is limited by low signal-to-noise ratio and background light environment when conducting long-distance and high-precision detection, making it difficult to achieve efficient and reliable ranging.
The system employs a current generation module, a current processing module, and a signal processing module. It converts differential current into voltage and performs counting and comparison within a time window with opposite phases to eliminate background light noise and achieve high signal-to-noise ratio ranging.
It expands the ranging range, eliminates background light noise, and achieves long-range lidar ranging with high signal-to-noise ratio.
Smart Images
Figure CN121806031A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of long-range lidar ranging technology, specifically relating to a long-range indirect time-of-flight lidar sensor integrated circuit. Background Technology
[0002] In recent years, driven by the continuous development of semiconductor laser, detector processes, and CMOS integrated circuit technology, the application scope of lidar is rapidly penetrating into various civilian scenarios. Indirect Time-of-Flight (iToF) lidar, relying on the ranging mechanism of modulation emission and pixel-level correlation demodulation, can achieve large-scale array integration on silicon-based processes and work in conjunction with on-chip timing control and digital calibration modules. This gives it advantages such as small size, low cost, and ease of mass production, demonstrating significant application value in areas such as near-to-mid-range perception for autonomous driving, obstacle avoidance and localization for intelligent robots, high-speed flight ranging for low-altitude UAVs, industrial measurement, and human-machine interaction. Facing more complex dynamic scenarios and the need for reliable detection at greater distances, long-range iToF lidar sensors are gradually becoming an important research hotspot.
[0003] Traditional iToF lidar requires four different phase time windows to cope with situations with low signal-to-noise ratios or long distances, but the final results are still poor. Therefore, it is necessary to carry out research on key technologies for long-range iToF lidar to overcome the bottleneck of the traditional iToF architecture in terms of the mutual constraints between long-range, high-precision, and strong background light environment detection. Summary of the Invention
[0004] To address the aforementioned problems in the prior art, this invention provides a long-range indirect time-of-flight lidar sensor integrated circuit. The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a long-range indirect time-of-flight lidar sensor integrated circuit, comprising: The current generation module, in response to the triggering result of the analog silicon photomultiplier tube pixel array, is used to output differential current; The current processing module, electrically connected to the current generation module, is used to convert differential current into voltage. The signal processing module, electrically connected to the current processing module, includes multiple counters and comparators. It generates multiple voltage pulses by ANDing the voltage with a high-frequency clock. The counters accumulate the number of voltage pulses within two windows with opposite phases to obtain the echo count value. The comparator finds the peak echo count and records its period. The peak echo count is then validated for data validity. If the data is valid, the peak echo count is processed and calculated to obtain the target distance information. If the data is invalid, the laser is re-emitted for a new round of ranging.
[0005] The beneficial effects of this invention are: The present invention provides a long-range indirect time-of-flight lidar sensor integrated circuit, including a current generation module, a current processing module, and a signal processing module. The signal processing module converts the output voltage into counting pulses and counts them in two time windows with opposite phases through a built-in counter, which greatly expands the measurement range. Then, the comparator finds the counting peak and processes it to obtain the distance information. The voltage pulses triggered by the background light are discarded, which is equivalent to eliminating the background light noise and achieving a high signal-to-noise ratio.
[0006] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0007] Figure 1 This is a schematic diagram of a long-range indirect time-of-flight lidar sensor integrated circuit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of a signal processing module provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a first pulse count counter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a first comparator provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of a first pulse count register provided in an embodiment of the present invention; Figure 6 This is a flowchart illustrating the operation of a long-range indirect time-of-flight lidar sensor integrated circuit provided in an embodiment of the present invention. Figure 7 This is a schematic diagram of the timing in the signal processing module provided in an embodiment of the present invention. Detailed Implementation
[0008] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.
[0009] The background of this invention is that after an indirect time-of-flight lidar emits a laser, the array of indirect time-of-flight lidar sensors receives the echo signal and further processes the echo signal.
[0010] Please see Figure 1 , Figure 1 This is a schematic diagram of a long-range indirect time-of-flight lidar sensor integrated circuit provided in an embodiment of the present invention. The long-range indirect time-of-flight lidar sensor integrated circuit provided by the present invention includes: The current generation module 10, in response to the triggering result of the analog silicon photomultiplier tube pixel array, is used to output differential current; optionally, such as Figure 1 As shown, the current output by the current generation module 10 is a differential current. and ; The current processing module 20 is electrically connected to the current generation module 10 and is used to convert differential current into voltage. The signal processing module 30, electrically connected to the current processing module 20, includes multiple counters and comparators. It is used to AND the voltage with a high-frequency clock to generate multiple voltage pulses. The counters accumulate the number of voltage pulses in two windows with opposite phases to obtain the echo count value. The comparator finds the peak value of the echo count and records its period. The peak value of the echo count is used to verify the data validity. If the data is determined to be valid, the peak value of the echo count is processed and calculated to obtain the target distance information. If the data is determined to be invalid, the laser is re-emitted to perform a new round of ranging.
[0011] In this embodiment, the signal processing module 30 converts the output voltage into counting pulses, finds the counting peak through a comparator, and then processes it to obtain distance information, which greatly expands the ranging range, further eliminates background light noise, and achieves a high signal-to-noise ratio. In other words, the signal processing module 30 converts the output voltage into counting pulses and counts them in two time windows with opposite phases through a built-in counter, which greatly expands the measurement range. Then, it finds the counting peak through a comparator and processes it to obtain distance information, discarding the voltage pulses triggered by background light, which is equivalent to eliminating background light noise and achieving a high signal-to-noise ratio.
[0012] In an optional embodiment of the present invention, please continue to refer to... Figure 1 The current processing module 20 includes a current subtractor circuit and a current comparator circuit; wherein, The current subtractor circuit is electrically connected to the current generation module 10 and is used to subtract the differential current output by the current generation module 10, i.e., the differential current. and Subtracting them gives the current difference. To eliminate common-mode interference, the current difference is compared with a current difference threshold. If the current difference is less than or equal to the current difference threshold, it is determined to be triggered by background light or noise, and the current subtractor circuit does not output the current difference. If the current difference is greater than the current difference threshold, the current subtractor circuit outputs the current difference. This effectively filters out background light noise and achieves a high signal-to-noise ratio for the circuit. The current comparator circuit is electrically connected to the current subtractor circuit to convert the current difference into an output voltage. .
[0013] Specifically, in this embodiment, the current processing module 20 adopts a differential structure, which can effectively suppress common-mode noise. Its basic structure is composed of a current mirror. By setting the current values of different branches of the current mirror and setting the current difference threshold, the suppression capability of the entire lidar sensor for background light noise can be significantly improved.
[0014] In an optional embodiment of the present invention, please refer to Figure 2 , Figure 2 This is a schematic diagram of a signal processing module 30 provided in an embodiment of the present invention. The signal processing module 30 includes a first cycle count counter, a first pulse count counter, a first comparator, a first cycle count register, a first pulse count register, a first AND gate, and a second AND gate; wherein, The first cycle counter counts the first reference clock corresponding to the first window to obtain the cycle number corresponding to the first window; the first AND gate ANDs the voltage with the high-frequency clock to obtain multiple voltage pulses; the second AND gate ANDs the voltage pulses with the first reference clock to establish a fixed relationship between the voltage pulses and the first reference clock; when the first reference clock is high, the first pulse counter counts the first counting pulses to obtain the first count value; the first comparator compares the first count value with the count value stored in the first pulse count register; if the first count value is greater than the count value stored in the first pulse count register, the count value stored in the first pulse count register is refreshed to the first count value; the first cycle register stores the cycle corresponding to the first count value, such as... Figure 2 As shown, the first comparator generates a control signal SEL1 to control switches S1 and S2 to turn on, thereby refreshing the count value stored in the first pulse count register and the period stored in the first cycle count register. If the first count value is less than the count value stored in the first pulse count register, no operation is performed until the maximum value of the first count value is obtained.
[0015] It should be noted that the first pulse count register always stores the maximum value of the first count.
[0016] In an optional embodiment of the present invention, the signal processing module 30 further includes a second cycle counter, a second pulse count counter, a second comparator, a second cycle register, a second pulse count register, and a third AND gate; wherein, The second cycle counter is used to count the second reference clock corresponding to the second window to obtain the cycle number corresponding to the second window; the third AND gate is used to AND the voltage pulse with the second reference clock to make the voltage pulse and the second reference clock have a fixed relationship; when the second reference clock is at a high level, the second pulse counter counts the second counting pulse to obtain the second count value; the second comparator compares the second count value with the count value stored in the second pulse count register. If the second count value is greater than the count value stored in the second pulse count register, the count value stored in the second pulse count register is refreshed to the second count value. The second cycle register stores the cycle corresponding to the second count value, such as... Figure 2 As shown, the second comparator generates a control signal SEL2 to turn on switches S3 and S4, thereby refreshing the count value stored in the second pulse count register and the period stored in the second cycle count register. If the second count value is less than the count value stored in the second pulse count register, no operation is performed until the maximum value of the second count value is obtained.
[0017] It should be noted that the second pulse count register always stores the maximum value of the second count.
[0018] Further, please see Figure 3 , Figure 3 This is a schematic diagram of a first pulse count counter provided in an embodiment of the present invention. The first pulse count counter includes multiple D flip-flops and counts voltage pulses within a first window. The input is the first counting pulse obtained by ANDing the voltage pulse with a first reference clock, and the output is CNT1<0:2>. As the data receiving end, This is the clock input terminal. This is the inverting output terminal. This is the positive output terminal.
[0019] It should be noted that the second pulse count counter has the same structure as the first pulse count counter, and will not be described again here.
[0020] Further, please see Figure 4 , Figure 4 This is a schematic diagram of a first comparator provided in an embodiment of the present invention. The first comparator includes multiple AND gates, OR gates and XNOR gates, used to compare the new round counting result CNT1<0:2> obtained by the first pulse count counter with the known maximum value CNT3<0:2> stored in the first pulse count register, generate a control signal SEL1 to control whether switches S1 and S2 are turned on. If they are turned on, the maximum value stored in the first pulse count register is refreshed.
[0021] It should be noted that the second comparator has the same structure as the first comparator, and will not be described again here.
[0022] Further, please see Figure 5 , Figure 5 This is a schematic diagram of a first pulse count register provided in an embodiment of the present invention. The first pulse count register includes multiple flip-flops. When the control signal SEL1 generated by the first comparator is high, that is, when the current first count value CNT1<0:2> in the first pulse count counter is greater than the data CNT3<0:2> stored in the first pulse count register, the data CNT3<0:2> in the first pulse count register is refreshed to the current count value CNT1<0:2> in the first pulse count counter, thereby realizing the retrieval of the maximum value of the first count value.
[0023] It should be noted that the structure of the second pulse count register is the same as that of the second pulse count register, and will not be described again here.
[0024] In an optional embodiment of the present invention, the first reference clock and the second reference clock are two clock signals with opposite phases.
[0025] Understandably, after the laser is emitted, the low-frequency synchronous clock and the inverting clock in the signal processing module 30 are turned on, and the high-frequency clock is split into phases to generate two time windows with phases of 0° and 180°. The 0° time window is the first time window, corresponding to the first reference clock, and the 180° time window is the second time window, corresponding to the second reference clock.
[0026] In an optional embodiment of the present invention, the signal processing module 30 further includes a data validity verification module for verifying the validity of the maximum value of the first count value and the maximum value of the second count value, so as to delete error data.
[0027] It should be noted that the verification conditions include: Is the period in which the maximum value of the first count obtained in the first window and the maximum value of the second count obtained in the second window are the same? Is the period in which the maximum value of the first count value obtained in the first window is located equal to the period in which the maximum value of the second count value obtained in the second window is increased by 1?
[0028] In an optional embodiment of the present invention, the signal processing module 30 further includes an indirect flight time information calculation module for calculating indirect flight time and target distance information.
[0029] Based on the same inventive concept, please refer to Figure 6 , Figure 6This is a flowchart illustrating the operation of a long-range indirect time-of-flight lidar sensor integrated circuit provided in an embodiment of the present invention. The present invention also provides a workflow for a long-range indirect time-of-flight lidar sensor integrated circuit to implement the long-range indirect time-of-flight lidar sensor integrated circuit provided in the above embodiments of the present invention. This workflow includes: S101, emits laser; S102. The echo signal is received through a simulated silicon photomultiplier tube pixel array, and a current is generated. S103, Convert current into voltage; S104. AND the voltage with a high-frequency clock to generate multiple voltage pulses; accumulate the number of voltage pulses in two windows with opposite phases to obtain the echo count value corresponding to the two windows with opposite phases, find the echo count peak value corresponding to the two windows with opposite phases, and obtain the period in which the echo count peak value is located; verify the validity of the echo count peak value corresponding to the two windows with opposite phases. If the data is determined to be valid, process and calculate the echo count peak value to obtain the target distance information. If the data is determined to be invalid, re-emit the laser and execute S102~S104 to perform a new round of ranging.
[0030] Specifically, in this embodiment, the indirect time-of-flight lidar emits a laser, which, after reflection from the target, is received by the indirect time-of-flight lidar sensor. This is triggered by a photoelectric avalanche diode, and a differential current is generated through a quenching and reset circuit, a pulse compression circuit, and a current generation circuit. After processing by the current processing module 20, this current is converted into an output voltage signal. The signal processing module 30 ANDs the voltage signal with a high-frequency clock signal to generate a series of voltage pulses. A built-in counter counts the voltage pulse signals within two time windows, 0° and 180°, respectively. A comparator then identifies the time window containing the maximum count. Registers store the maximum count and its corresponding period, further verifying the validity of the count data. For valid count data, target distance information is calculated. Thus, at the end of the measurement, the pulse count register stores the maximum pulse count, while the period count register stores the corresponding period count for subsequent modules to process. This process finds the peak value of the count pulses, significantly expanding the ranging range, further eliminating background light noise, and achieving a high signal-to-noise ratio.
[0031] In an optional embodiment of the present invention, please refer to Figure 7 , Figure 7 This is a schematic diagram of the timing of the signal processing module 30 provided in an embodiment of the present invention. It processes and calculates the echo count peak value to obtain target distance information, including: If the maximum value of the first count obtained in the first window and the maximum value of the second count obtained in the second window are in the same period, that is... Then obtain the indirect flight time. , is represented as: ; in, This indicates the period containing the maximum value of the first count value obtained within the first window. This indicates the period in which the maximum value of the second count value obtained within the second window is located. This indicates the maximum value of the first count obtained within the first window. This indicates the maximum value of the second count obtained within the second window; Indicates the phase clock period; According to the indirect flight time Obtain target distance information , is represented as: ; in, It represents the speed of light.
[0032] In an optional embodiment of the present invention, please continue to refer to... Figure 7 The echo count peaks are processed and calculated to obtain target distance information, including: If the period of the maximum value of the first count obtained in the first window is the period of the maximum value of the second count obtained in the second window plus 1, that is... Then obtain the indirect flight time. , is represented as: ; in, This indicates the period containing the maximum value of the first count value obtained within the first window. This indicates the period in which the maximum value of the second count value obtained within the second window is located. This indicates the maximum value of the first count obtained within the first window. This indicates the maximum value of the second count obtained within the second window; Indicates the phase clock period; Based on indirect flight time Obtain target distance information , is represented as: ; in, It represents the speed of light.
[0033] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element. Terms such as "connected" or "linked" are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect. The orientations or positional relationships indicated by terms such as "upper," "lower," "left," and "right" are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.
[0034] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.
[0035] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.
Claims
1. A long-range indirect time-of-flight lidar sensor integrated circuit, characterized in that, include: The current generation module, in response to the triggering result of the analog silicon photomultiplier tube pixel array, is used to output differential current; A current processing module, electrically connected to the current generating module, is used to convert the differential current into voltage; The signal processing module, electrically connected to the current processing module, includes multiple counters and comparators. It generates multiple voltage pulses by ANDing the voltage with a high-frequency clock. The counters accumulate the number of voltage pulses within two windows with opposite phases to obtain an echo count value. The comparator finds the peak echo count and records its period. The peak echo count is then validated for data validity. If the data is valid, the peak echo count is processed and calculated to obtain the target distance information. If the data is invalid, the laser is re-emitted for a new round of ranging.
2. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 1, characterized in that, The current processing module includes a current subtractor circuit and a current comparator circuit; wherein... The current subtractor circuit is electrically connected to the current generation module and is used to subtract the differential current output by the current generation module to obtain a current difference, thereby eliminating common-mode interference. The current difference is compared with a current difference threshold. If the current difference is less than or equal to the current difference threshold, it is determined to be triggered by background light or noise, and the current subtractor circuit does not output a current difference. If the current difference is greater than the current difference threshold, the current subtractor circuit outputs a current difference. The current comparator circuit is electrically connected to the current subtractor circuit and is used to convert the current difference into an output voltage.
3. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 1, characterized in that, The signal processing module includes a first cycle count counter, a first pulse count counter, a first comparator, a first cycle count register, a first pulse count register, a first AND gate, and a second AND gate; wherein... The first cycle counter is used to count the first reference clock corresponding to the first window to obtain the cycle number corresponding to the first window; the first AND gate is used to AND the voltage with the high-frequency clock to obtain multiple voltage pulses, and the second AND gate is used to AND the voltage pulse with the first reference clock to obtain a first counting pulse, so that the voltage pulse and the first reference clock have a fixed relationship; when the first reference clock is at a high level, the first pulse counter counts the first counting pulse to obtain a first count value; the first comparator compares the first count value with the count value stored in the first pulse count register. If the first count value is greater than the count value stored in the first pulse count register, the count value stored in the first pulse count register is refreshed to the first count value, and the first cycle register stores the cycle corresponding to the first count value. If the first count value is less than the count value stored in the first pulse count register, no operation is performed until the maximum value of the first count value is obtained.
4. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 3, characterized in that, The signal processing module further includes a second cycle counter, a second pulse count counter, a second comparator, a second cycle register, a second pulse count register, and a third AND gate; wherein, The second cycle counter is used to count the second reference clock corresponding to the second window to obtain the cycle number corresponding to the second window; the third AND gate is used to AND the voltage pulse with the second reference clock to obtain the second counting pulse, so that the voltage pulse and the second reference clock have a fixed relationship; when the second reference clock is at a high level, the second pulse counter counts the second counting pulse to obtain the second count value; the second comparator compares the second count value with the count value stored in the second pulse count register. If the second count value is greater than the count value stored in the second pulse count register, the count value stored in the second pulse count register is refreshed to the second count value, and the second cycle register stores the cycle corresponding to the second count value. If the second count value is less than the count value stored in the second pulse count register, no operation is performed until the maximum value of the second count value is obtained.
5. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 4, characterized in that, The first reference clock and the second reference clock are two clock signals with opposite phases.
6. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 4, characterized in that, The signal processing module further includes a data validity verification module, which is used to verify the validity of the maximum value of the first count value and the maximum value of the second count value in order to delete erroneous data.
7. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 4, characterized in that, The signal processing module also includes an indirect flight time information calculation module, used to calculate indirect flight time and target distance information.
8. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 1, characterized in that, The target distance information is obtained by processing and calculating the echo count peak value, including: If the maximum value of the first count obtained in the first window and the maximum value of the second count obtained in the second window are in the same period, that is... Then obtain the indirect flight time. , is represented as: ； in, This indicates the period containing the maximum value of the first count value obtained within the first window. This indicates the period in which the maximum value of the second count value obtained within the second window is located. This indicates the maximum value of the first count obtained within the first window. This indicates the maximum value of the second count obtained within the second window; Indicates the phase clock period; According to the indirect flight time Obtain target distance information , is represented as: ； in, It represents the speed of light.
9. The long-range indirect time-of-flight lidar sensor integrated circuit according to claim 1, characterized in that, The target distance information is obtained by processing and calculating the echo count peak value, including: If the period of the maximum value of the first count obtained in the first window is the period of the maximum value of the second count obtained in the second window plus 1, that is... Then obtain the indirect flight time. , is represented as: ； in, This indicates the period containing the maximum value of the first count value obtained within the first window. This indicates the period in which the maximum value of the second count value obtained within the second window is located. This indicates the maximum value of the first count obtained within the first window. This indicates the maximum value of the second count obtained within the second window; Indicates the phase clock period; According to the indirect flight time Obtain target distance information , is represented as: ； in, It represents the speed of light.