System and method for signal processing in light detection and ranging (LIDAR) systems

Abstract

The present technology relates to systems and methods for signal processing in light detection and ranging (LIDAR) systems. In an embodiment, the present technology provides an apparatus comprising: an optical module configured to receive a first optical signal; and a first circuit configured to generate a first electrical signal based on the first optical signal. The apparatus also includes a first comparator configured to generate a second electrical signal by comparing the first electrical signal to a first threshold. The apparatus further includes a first filter configured to generate a first pulse based on the second electrical signal. The first pulse includes a first point associated with a first timestamp. The timestamp data may be briefly retained in the analog domain followed by subsequent digital transformations, allowing significant power savings and reduced system bandwidth. Other embodiments are also present.

Description

Technical Field

[0001] The present technology relates to systems and methods for light detection and ranging (LIDAR) technology. Background Art

[0002] Over the past few decades, advances in remote sensing technology have pushed systems to higher levels of environmental responsiveness. These technologies have enabled systems to understand, interpret, and interact with their surroundings. Various approaches involve laser-based sensing technologies, such as light detection and ranging (LIDAR) applications, which can provide high-resolution environmental data (e.g., depth maps) to indicate the proximity of different objects to the LIDAR device. For example, LIDAR devices (which can utilize single-pixel or multi-pixel sensors) can detect depths of up to hundreds of meters, ensuring accuracy within narrow tolerances. To match such accuracy standards, LIDAR pulse durations are fine-tuned to only nanoseconds. This requires the corresponding system front-end (especially the system front-end tied to the photosensitive detector) to maintain high bandwidth. Given the large number of bandwidth constraints, effectively managing signal processing on numerous channels and achieving seamless integration of various system components remains a challenging task.

[0003] Various methods for optimizing signal processing for LIDAR applications have been explored, but have proven to be insufficient. It is important to recognize that new and improved systems and methods are needed for LIDAR applications. Summary of the invention

[0004] On the one hand, the present disclosure relates to a device, comprising: an optical module, which is configured to receive a first optical signal; a first circuit, which is coupled to the optical module, the first circuit is configured to generate a first electrical signal based on at least the first optical signal; a first comparator, which is coupled to the first circuit, the first comparator is configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter, which is coupled to the first comparator, the first filter is configured to generate a third electrical signal based on at least the second electrical signal, the third electrical signal including a first pulse, the first pulse including a first point associated with a first timestamp; a second circuit, which is coupled to the first filter, the second circuit is configured to generate a fourth electrical signal based on at least the first pulse; and a memory, which is configured to receive the fourth electrical signal and store the first timestamp.

[0005] On the other hand, the present disclosure relates to a device, comprising: an optical module, which is configured to receive a first optical signal; a first circuit, which is coupled to the optical module, and the first circuit is configured to generate a first electrical signal based on at least the first optical signal; a first comparator, which is coupled to the first circuit, and the first comparator is configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter, which is coupled to the first comparator, and the first filter is configured to generate a third electrical signal based on at least the second electrical signal, and the third electrical signal includes a first pulse, and the first pulse includes a first point associated with a first timestamp; a second circuit, which is coupled to the first filter, and the second circuit is configured to generate a fourth electrical signal based on at least the first pulse; and a memory, which is coupled to the second circuit, and the memory is configured to receive the fourth electrical signal and store the first timestamp.

[0006] On the other hand, the present disclosure relates to a device, comprising: an optical module, which is configured to receive a first optical signal; a first circuit, which is coupled to the optical module, and the first circuit is configured to generate a first electrical signal based on at least the first optical signal; a first comparator, which is coupled to the first circuit, and the first comparator is configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter, which is coupled to the first comparator, and the first filter is configured to generate a third electrical signal based on at least the second electrical signal, and the third electrical signal includes a first pulse, the first pulse includes a first point and a second point, the first point is associated with a first timestamp, and the second point is associated with a second timestamp; a second circuit, which is coupled to the first filter, and the second circuit is configured to generate a fourth electrical signal based on at least the first pulse; and a memory, which is configured to receive the fourth electrical signal and store a third timestamp based on at least the first timestamp and the second timestamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A further understanding of the nature and advantages of particular embodiments may be achieved by reference to the remainder of the specification and the accompanying drawings, in which the same reference element symbols are used to refer to similar components. In some instances, a sub-label is associated with a reference element symbol to represent one of multiple similar components. When reference is made to a reference element symbol without detailing the existing sub-label, it is intended to refer to all such multiple similar components.

[0008] Figure 1 is a simplified diagram illustrating a LIDAR system in accordance with an embodiment of the present technology.

[0009] Figure 2 is a simplified diagram illustrating a signal processing scheme for a LIDAR system in accordance with an embodiment of the present technology.

[0010] Figure 3 is a simplified diagram illustrating a signal processing scheme for a LIDAR system in accordance with an embodiment of the present technology.

[0011] Figure 4 is a simplified diagram illustrating a simulated implementation of a signal processing scheme for a LIDAR system in accordance with an embodiment of the present technology.

[0012] Figure 5 is a simplified diagram illustrating a simulated implementation of a signal processing scheme for a LIDAR system in accordance with an embodiment of the present technology.

[0013] Figure 6 is a simplified diagram illustrating filters for a LIDAR system in accordance with an embodiment of the present technology. DETAILED DESCRIPTION

[0014] The present technology relates to light detection and ranging (LIDAR) systems and methods. In an embodiment, the present technology provides a device comprising: an optical module configured to receive a first optical signal; and a first circuit configured to generate a first electrical signal based on the first optical signal. The device also includes a first comparator configured to generate a second electrical signal by comparing the first electrical signal with a first threshold. The device further includes a first filter configured to generate a first pulse based on the second electrical signal. The first pulse includes a first point associated with a first timestamp. The timestamp data can be briefly maintained in the analog domain, followed by subsequent digital conversion, thereby allowing significant power savings and reducing system bandwidth. Other embodiments exist.

[0015] As is well known, a time-of-flight (ToF) LIDAR system operates by transmitting a light beam to a target object and then waiting to receive a reflected portion of the emitted light after being reflected by the target object. The elapsed time between the transmission and reception of the light beam is used to calculate the distance between the LIDAR system and the target object. Such systems utilize what is commonly known as direct ToF calculations because they rely directly on the time of flight to determine the distance. Direct ToF LIDAR systems typically focus on discerning the arrival time of signal echoes, which requires distinguishing these echoes from other noise. The term "signal echo" or "echo signal" may refer to the reflection of a transmitted optical signal that bounces back to the sensor after hitting an object. For example, a LIDAR system may adapt its associated analog / digital converter (ADC) in a manner that values ​​efficient detection of these echo signals. This is to ensure accuracy in distance measurement and facilitate high-resolution imaging. However, due to the presence of noise, it may be challenging to balance efficiency and accuracy. The term "noise" may encompass all forms of irrelevant signals, which may originate from various sources such as background light, detector interference, dark counts, and / or amplifier interruptions.

[0016] Due to the complexity of signal processing, where multiple signal returns are evaluated within a limited time frame, time constraints become an important aspect of LIDAR design. These time-sensitive limitations can determine how well the LIDAR system can distinguish closely spaced objects. In addition, the consideration becomes more complicated in view of the amplitude variation of the received return signal. For example, some objects may produce weaker reflections than other objects, thereby introducing amplitude variations in the return signal, which can complicate the signal discrimination process.

[0017] In various embodiments, the present technology provides a LIDAR system that effectively addresses the challenge of closely spaced object discrimination without compromising signal fidelity or detection efficiency. This is achieved by introducing a series of adaptive thresholds in the ADC, which span a wide amplitude range to ensure high fidelity detection of echoes from near and far objects. With this adaptability of threshold settings, the LIDAR system can be designed to be more versatile and able to operate in a variety of environments, from dense urban environments to open areas. Through the adaptive selection of these thresholds, the LIDAR system can achieve shorter processing times, thereby improving both signal quality and data acquisition rate. In addition, the results of the echo signal evaluation can be temporarily stored in the analog domain using analog storage elements such as capacitors or inductors. This transient analog retention can then lead to delayed digitization, thereby alleviating the strict performance requirements for data interconnection and ADC. Embodiments of the present technology provide a LIDAR system with improved operating efficiency marked by faster response times and lower energy requirements.

[0018] The following description is presented to enable one of ordinary skill in the art to make and use the present disclosure and incorporate it into a specific application context. One of ordinary skill in the art will readily appreciate the various modifications and various uses in different applications, and the general principles defined herein can be applied to a variety of embodiments. Therefore, the present technology is not intended to be limited to the embodiments presented, but should be given the widest scope consistent with the principles and novel features disclosed herein.

[0019] In the following detailed description, many specific details are set forth in order to provide a more thorough understanding of the present technology. However, it should be understood by those skilled in the art that the present technology can be practiced without being limited to these specific details. In other examples, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring the present technology.

[0020] The reader's attention is directed to all papers and documents filed with this specification and open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. Unless expressly stated otherwise, all features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose. Therefore, unless expressly stated otherwise, each feature disclosed is only one example of a series of generic equivalent or similar features.

[0021] Furthermore, any element in a claim that does not explicitly state a “means” for performing a specific function or a “step” for performing a specific function should not be interpreted as a “means” or “step” clause as provided in 35 USC § 112, paragraph 6. In particular, the use of “the step of” or “the action of” in the claims herein is not intended to invoke the provisions of 35 USC § 112, paragraph 6.

[0022] When an element is referred to herein as being "connected" or "coupled" to another element, it is understood that the element may be directly connected to the other element or have an intervening element present between the elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, it is understood that there are no intervening elements in the "direct" connection between the elements. However, the presence of a direct connection does not exclude other connections in which intervening elements may be present.

[0023] When an element is referred to herein as being "disposed" in some manner relative to another element (e.g., disposed on another element, disposed between additional elements, disposed below another element, disposed adjacent to another element, or disposed in some other relative manner), it is understood that the element may be disposed directly relative to another element (e.g., disposed directly on another element) or have intervening elements present between the elements. In contrast, when an element is referred to as being "directly disposed" relative to another element, it is understood that in the "direct" instance there are no intervening elements. However, the presence of a direct disposition does not exclude other instances in which intervening elements may be present.

[0024] Similarly, when an element is referred to herein as being "joined" to another element, it is understood that the element may be directly joined to the other element (without any intervening elements) or have an intervening element present between the joined elements. In contrast, when an element is referred to as being "directly joined" to another element, it is understood that there are no intervening elements in the "direct" joining between the elements. However, the presence of direct joining does not exclude other forms of joining in which intervening elements may be present.

[0025] Likewise, when an element is referred to herein as a "layer," it is understood that the layer may be a single layer or may include multiple layers. For example, a conductive layer may include a plurality of different conductive materials or multiple layers of different conductive materials, and a dielectric layer may include a plurality of dielectric materials or multiple layers of dielectric materials. When a layer is described as being coupled or connected to another layer, it is understood that the coupled or connected layer may include an intervening element that is present between the coupled or connected layers. In contrast, when an element is referred to as being "directly" connected or coupled to another layer, it is understood that there are no intervening elements between the layers. However, the presence of a directly coupled or connected layer does not exclude other connections in which intervening elements may be present.

[0026] In addition, the terms left, right, front, back, top, bottom, forward, reverse, clockwise and counterclockwise are used only for explanation purposes and are not limited to any fixed direction or orientation. Instead, they are only used to indicate the relative position and / or direction between the various parts of an object and / or component.

[0027] In addition, for ease of description, the methods and processes described herein may be described in a particular order. However, it should be understood that unless the context otherwise requires, the intermediary processes may occur before and / or after any portion of the described processes, and further various procedures may be reordered, added, and / or omitted according to various embodiments.

[0028] Unless otherwise indicated, all numbers used herein to express quantities, sizes, etc. should be understood to be modified by the term "about" in all instances. In this application, unless otherwise specifically stated, the use of the singular includes the plural, and unless otherwise indicated, the use of the terms "and" and "or" means "and / or". In addition, the use of the terms "including" and "having" and other forms (such as "includes / included", "has / have / had") should be considered non-exclusive. Moreover, unless otherwise specifically stated, terms such as "element" or "component" cover both elements and components including one unit and elements and components including more than one unit.

[0029] As used herein, the phrase "at least one of..." following a list of items (where the terms "and" or "or" are used to separate any of the items) modifies the entire list rather than each member of the list (i.e., each item). The phrase "at least one of..." does not require selection of at least one of each listed item; rather, the phrase allows for a meaning that includes at least one of any of the items and / or at least one of any combination of the items. For example, the phrase "at least one of A, B, and C" or "at least one of A, B, or C" each refers to only A, only B, or only C and / or any combination of A, B, and C. In instances where the desired selection is "at least one of each of A, B, and C," or alternatively, "at least one of A, at least one of B, and at least one of C," it is expressly described as such.

[0030] One general aspect includes a device comprising an optical module configured to receive a first optical signal. The device further comprises a first circuit coupled to the optical module; the first circuit is configured to generate a first electrical signal based at least on the first optical signal. The device further comprises a first comparator coupled to the first circuit, the first comparator being configured to generate a second electrical signal by comparing the first electrical signal to a first threshold. The device further comprises a first filter coupled to the first comparator, the first filter being configured to generate a third electrical signal based at least on the second electrical signal. The third electrical signal comprises a first pulse, the first pulse comprising a first point associated with a first timestamp. The device further comprises a second circuit coupled to the first filter, the second circuit being configured to generate a fourth electrical signal based at least on the first pulse. The device further comprises a memory configured to receive the fourth electrical signal and store the first timestamp.

[0031] The implementation may include one or more of the following features. The device further includes a second comparator coupled to the first circuit, the second comparator being configured to compare the first electrical signal with a second threshold. The device further includes a second filter coupled to the second comparator. The memory includes a capacitor or an inductor. The device further includes a third circuit coupled to the memory, the third circuit being configured to read the first timestamp and send a first signal to the second circuit to reset the memory. The first pulse includes a rising pulse in response to the first electrical signal being above the first threshold. The first pulse includes a falling pulse in response to the first electrical signal being below the first threshold. The first filter is configured to determine the width of the first pulse. The device further includes a fourth circuit coupled to the first comparator, the fourth circuit being configured to adjust the first threshold. The fourth electrical signal includes an analog signal.

[0032] According to another embodiment, the present technology provides a device comprising an optical module configured to receive a first optical signal. The device further comprises a first circuit coupled to the optical module, the first circuit being configured to generate a first electrical signal based at least on the first optical signal. The device further comprises a first comparator coupled to the first circuit, the first comparator being configured to generate a second electrical signal by comparing the first electrical signal with a first threshold. The device further comprises a first filter coupled to the first comparator, the first filter being configured to generate a third electrical signal based at least on the second electrical signal, the third electrical signal comprising a first pulse, the first pulse comprising a first point associated with a first timestamp. The device further comprises a second circuit coupled to the first filter, the second circuit being configured to generate a fourth electrical signal based at least on the first pulse. The device further comprises a memory coupled to the second circuit, the memory being configured to receive the fourth electrical signal and store the first timestamp.

[0033] The implementation may include one or more of the following features. The device further includes a second comparator coupled to the first circuit, the second comparator being configured to generate a fifth electrical signal by comparing the first electrical signal with a second threshold. The device further includes a second filter coupled to the second comparator, the second filter being configured to generate a sixth electrical signal based at least on the fifth electrical signal, the sixth electrical signal including a second pulse, the second pulse including a second point associated with a second timestamp. The device further includes a fourth circuit coupled to the second filter, the fourth circuit being configured to generate a seventh electrical signal based at least on the second pulse. A memory is coupled to the fourth circuit, and the memory is configured to receive the seventh electrical signal and store the second timestamp. The device further includes a fifth circuit coupled to the first comparator, the fifth circuit being configured to adjust the first threshold.

[0034] According to yet another embodiment, the present technology provides a device comprising an optical module configured to receive a first optical signal. The device further comprises a first circuit coupled to the optical module, the first circuit being configured to generate a first electrical signal based at least on the first optical signal. The device further comprises a first comparator coupled to the first circuit, the first comparator being configured to generate a second electrical signal by comparing the first electrical signal with a first threshold. The device further comprises a first filter coupled to the first comparator, the first filter being configured to generate a third electrical signal based at least on the second electrical signal, the third electrical signal comprising a first pulse, the first pulse comprising a first point and a second point, the first point being associated with a first timestamp, and the second point being associated with a second timestamp. The device further comprises a second circuit coupled to the first filter, the second circuit being configured to generate a fourth electrical signal based at least on the first pulse. The device further comprises a memory configured to receive the fourth electrical signal and store a third timestamp based at least on the first timestamp and the second timestamp.

[0035] Implementations may include one or more of the following features. The first pulse further includes a third point located between the first point and the second point, the third point being associated with a third timestamp. The memory includes a capacitor or an inductor. The device further includes a third circuit coupled to the memory, the third circuit being configured to read the third timestamp. The fourth electrical signal includes an analog signal.

[0036] Figure 1 1 is a simplified diagram illustrating a LIDAR system 100 according to an embodiment of the present technology. This diagram provides an example only, which should not unduly limit the scope of the claims. A person of ordinary skill in the art will recognize many variations, substitutions, and modifications.

[0037] As shown, the LIDAR system 100 may include at least one of a light source 104, a driver 102, a transmitter module 106, a receiver module 110, a detector 112, a front end 114, and a control module 124. In operation, the light source 104 emits a light beam 130 through the transmitter module 106. The light source 104 may include any device capable of generating light of a specific wavelength in the infrared, visible, or ultraviolet portion of the electromagnetic spectrum. For example, the light source 104 includes, but is not limited to, an edge emitting laser (EEL), a quantum well laser, a distributed Bragg reflector (DBR) laser, a distributed feedback (DFB) laser, a vertical cavity surface emitting laser (VCSEL), a pulsed solid-state laser, a pulsed fiber laser, and / or the like. Depending on the implementation, the light beam 130 may be continuous wave, pulsed, or modulated. For example, the light source 104 includes a pulsed laser or a pulsed light emitting diode (LED) configured to emit light pulses having a specific pulse duration (e.g., less than 20 nanoseconds). Transmitter module 106 may include one or more optical or electrical elements (such as lenses, bandpass filters, interference filters, beam splitters, polarizers, modulators, or amplifiers) to ensure that light beam 130 is properly shaped, focused, and directed to maximize the range and accuracy of LIDAR system 100.

[0038] In some embodiments, driver 102 is coupled to light source 104 and is configured to supply and modulate current or voltage to drive light source 104. Driver 102 can control various properties of light beam 130, such as its width, shape, frequency, and amplitude. In some cases, this modulation is managed by control module 124 and adapted to meet specific implementation requirements of LIDAR system 100 (e.g., power, distance, and resolution).

[0039] In some embodiments, the light beam 130 reflects after reaching the target 108. The target 108 may be located at a distance from the LIDAR system 100, perhaps up to hundreds of meters. The target 108 may reflect at least a portion of the light from the light beam 130, and some of the reflected light may return to the LIDAR system 100. For example, the reflected light represented by the optical signal 132 (e.g., the first optical signal described in claim 1) may be received by the receiver module 110 (e.g., the optical module described in claim 1). The term "optical signal" may refer to a light beam emitted by a light source of the LIDAR system and reflected to the system by a target object. The optical signal in the LIDAR system is characterized by its wavelength, pulse width, power, and polarization. The optical signal can be used to determine the distance between the LIDAR system and the target object and the physical properties of the object, such as its shape and texture.

[0040] In various implementations, the receiver module 110 may include one or more optical or electrical elements (e.g., lenses, bandpass filters) to effectively capture and direct the reflected optical signal 132 onto the detector 112. The detector 112 (e.g., the first circuit described in claim 1) may include electronic components configured to receive the optical signal 132 and generate a corresponding electrical signal. For example, the detector 112 includes (but is not limited to) an indirect bandgap-based detector, such as an avalanche photodiode (APD), a single-photon avalanche diode (SPAD), a PN photodiode, a PIN photodiode, a silicon photomultiplier (SiPM), and / or the like. Alternatively, a direct bandgap-based detector, such as InGaAs or the like, may also be used. As an example, the detector 112 is configured to generate a first electrical signal (e.g., a photodiode) based at least on the optical signal 132. Figure 1 The term "electrical signal" may refer to an electrical representation of the optical signal 132. The electrical signal is generated when the detector converts the photon flux of the optical signal into an electric current. The electric current may be sensed by the first stage of the front end 114 and converted into a voltage representation. The electrical signal may include a voltage of varying amplitude and frequency depending on the characteristics of the optical signal. The electrical signal may include an analog representation of a continuous-time signal that preserves the complex changes in amplitude and time properties observed in the optical signal 132, thereby providing a rich data source for subsequent processing and analysis.

[0041] In various embodiments, the detector 112 may be coupled to a front end 114 that includes electrical components configured to perform one or more signal pre-processing steps (e.g., signal amplification, sampling, filtering, signal conditioning) to prepare the raw electrical signal for later processing and analysis. For example, the front end 114 includes an amplifier that is configured to amplify the received optical signal 132 and provide the amplified signal for subsequent processing.

[0042] According to some embodiments, the control module 124 (e.g., the third circuit described in claim 5) manages the operation and various aspects of the LIDAR system 100. As shown, the control module 124 is coupled to the driver 102 and is configured to send control signals (e.g., electrical pulses or modulated waveforms) to the driver 102 and control the emission cycle of the light source 104. For example, the control module 124 can send a control signal to trigger the light source 104 to emit the light beam 130. The control module 124 allows dynamic modulation of the beam properties, such as frequency, period, duration, pulse energy, peak power, average power, and wavelength. Depending on the implementation, the control module 124 can be implemented using one or more microprocessors. In addition to providing control signals to the driver 102, the control module 124 can also send one or more signals to activate and manage other components of the LIDAR system 100 to process received optical signals (e.g., optical signal 132).

[0043] As an example, the LIDAR system 100 includes a comparator 116 (e.g., the first comparator described in claim 1) coupled to the detector 112 or the front end 114. The term "comparator" may refer to a device that compares two electrical signals and determines their relationship (e.g., equality, inequality, or difference in magnitude). For example, the comparator 116 includes (but is not limited to) a voltage comparator, a current comparator, or others. In various examples, the comparator 116 is configured to receive a first electrical signal and generate a second electrical signal by comparing the first electrical signal to a first threshold. For example, the comparator 116 receives a first input threshold signal Xthres,0 (characterized by a first threshold) and compares the first electrical signal SigRx to the first threshold. In some cases, the second electrical signal generated by the comparator 116 may include a positive signal indicating when a comparison criterion is met (e.g., when the first electrical signal crosses the first threshold).

[0044] Depending on the application, the LIDAR system 100 may include multiple comparators, each of which is characterized by a threshold. For example, a comparator 126 (e.g., the second comparator described in claim 2) may be coupled to the detector 112 or the front end 114. The comparator 126 may receive a second input threshold signal Xthres,1 (characterized by a second threshold) and compare the first electrical signal SigRx to the second threshold. Depending on the application, the threshold associated with each comparator may be dynamically adjusted or statically set. For example, the established threshold may be configured to span the expected amplitude variation of the received optical signal 132. By employing multiple comparators with different thresholds, the LIDAR system 100 enhances signal detection across a wide amplitude range, thereby allowing for improved sensitivity and reliability in different operating environments.

[0045] In various implementations, the second electrical signal generated by the comparator 116 may be output to a filter 118 (e.g., the first filter described in claim 1). The term "filter" or "event filter" may refer to an electronic component designed to distinguish and discern a specific event from a continuous or quasi-continuous input signal (e.g., the second electrical signal). In some embodiments, the event detected by the filter 118 involves distinguishing a specific feature or characteristic of the signal, such as identifying when the signal crosses a certain threshold in a specific direction. For example, the filter 118 is configured to identify a rising event, which may refer to an instance in which the second electrical signal rises above an associated threshold (e.g., the first threshold) in a positive or upward direction (e.g., from a lower value to a threshold). The filter 118 is also configured to identify a falling event, which may refer to an instance in which the second electrical signal falls below the same threshold in a negative or downward direction (e.g., from a higher value to a threshold). In some cases, the LIDAR system 100 further includes a filter 128 (e.g., the second filter described in claim 3) coupled to the comparator 126.

[0046] After identifying a particular condition (e.g., a rising event or a falling event), the filter 118 is configured to generate a third electrical signal based at least on the second electrical signal. The third electrical signal may include a first pulse indicating the detected condition. For example, if it is a rising event, the filter 118 may generate a first pulse including a rising pulse in response to the first electrical signal being above a first threshold. The term "rising pulse" may refer to the edge of an electrical signal with increased intensity. If it is a falling event, the filter 118 may generate a first pulse including a falling pulse in response to the first electrical signal being below a first threshold. The term "falling pulse" may refer to the edge of an electrical signal with reduced intensity. The first pulse captures both amplitude and time information about the event, thereby providing a rich data set for subsequent signal processing and ToF calculations. In various examples, the filter 118 is configured to determine the width of the first pulse. The term "width" or "width of a pulse" may refer to the time range or duration of a pulse. For example, the width characterizes the time it takes for the first pulse to transition from a low or zero state to its peak value and back to a low or zero state. The width is critical to capturing temporal information about the event that triggered the first pulse, such as the arrival of an optical signal or a specific change in an electrical signal.

[0047] In some embodiments, the LIDAR system 100 further includes a circuit 120 (e.g., the second circuit described in claim 1) coupled to the filter 118. The fourth electrical signal may include an analog signal. The term "analog signal" may refer to a continuous time electrical signal that is used as a representation of the optical signal received by the LIDAR system. The circuit 120 may be configured to generate the fourth electrical signal based on at least the first pulse. For example, the circuit 120 may be coupled to a memory 122 and may capture the time value contained in the first pulse and store it in the analog domain at the memory 122. In an example, the first pulse includes a first point associated with a first timestamp, which may be temporarily stored in the analog domain at the memory 122. The term "timestamp" may refer to a set of data or a time mark indicating the precise time occurrence of an event (e.g., the rise or fall of the first pulse). For example, the timestamp may be in the form of a charge or voltage level representing a discrete time point. It should be understood that storing the timestamp "in the analog domain" means that the time information representing the precise time occurrence of the event remains in its continuous, unquantized form. This raw representation preserves the complex amplitude variations and temporal nuances observed in the original signal, thus capturing a rich data set that is critical to accurate signal interpretation.

[0048] In various implementations, memory 122 may include one or more analog storage elements, such as capacitors or inductors. The term "analog storage element" refers to a device capable of temporarily holding an analog signal, which is a continuous time signal that can take any value within a defined range. The term "capacitor" refers to an electrical component that can store energy in the form of an electric field. It consists of two conductive plates separated by a dielectric material. When a voltage is applied to a capacitor, it charges by storing electrons on one plate and creating an electron deficit on the other plate. The term "inductor" refers to an electrical component that can store energy in the form of a magnetic field. It consists of a coil of wire. When current flows through the inductor, it creates a magnetic field around the coil. Both capacitors and inductors can be used to store timestamps in the analog domain. For example, a capacitor or inductor is used to create a circuit designed to delay a signal for a specific amount of time. The timestamp is then stored by measuring the delay time.

[0049] Depending on the implementation, the timestamps saved in the memory 122 may be further evaluated or processed in the analog domain or may remain stored for subsequent digitization. In some cases, at the beginning of each cycle (when the beam is activated), the control module 124 may generate a start signal to reset the stored timestamps at the memory 122. By temporarily storing the timestamp information in the analog domain, the system alleviates the time-sensitive constraints typically associated with immediate digital conversion. This approach effectively eliminates the need for high-bandwidth data links and alleviates operational intensity, thereby reducing overall power consumption and system latency.

[0050] According to various embodiments, the control module 124 (e.g., the third circuit described in claim 5) may be coupled to the memory 122 and configured to read the stored timestamp from the memory 122. As an example, the term "read" or "readout" may refer to a function or capability to access, retrieve, or interpret a stored time (e.g., a first timestamp). For example, the control module 124 may include a readout integrated circuit (ROIC) designed to read / process signals from the memory 122. The readout mechanism may involve utilizing specific semiconductor components (e.g., metal oxide semiconductor field effect transistors (MOSFETs)) together with a bias current source. For example, a MOSFET may be actuated to implement a control current, thereby allowing accurate and efficient retrieval of a stored analog time value, which may then be converted into a digital format for further processing.

[0051] Figure 2 is a simplified diagram illustrating a signal processing scheme for a LIDAR system according to an embodiment of the present technology. This diagram provides an example only, which should not unduly limit the scope of the claims. A person of ordinary skill in the art will recognize many variations, substitutions, and modifications. As previously mentioned, a LIDAR system may employ multiple thresholds for a single interpretation. For example, a LIDAR system may include multiple comparators (e.g., Figure 1 Each of the comparators 116 is associated with a threshold value. Figure 2 As shown in FIG. 1 , the signal SigRx represents a received optical signal that is detected due to the interaction between the transmitted light beam and the target. The amplitude of SigRx is compared to four thresholds denoted as thres0, thres1, thres2, and thres3. The timestamps denoted as t0, t1, ..., t12 indicate the time (on the x-axis) when the signal SigRx crosses one of the thresholds in the rising or falling direction. For example, the signal SigRX passes through the threshold thres0 in the rising direction at time t0, passes through the threshold thres1 in the rising direction at time t1, passes through the threshold thres2 in the falling direction at time t2, and so on. By recording these events, the LIDAR system can generate an electrical signal denoted as Sigrec (e.g., using Figure 1 The filter 118 may include a first pulse. The amplitude or envelope of the first pulse may be determined by plotting various thresholds at various time stamps.

[0052] Depending on the implementation, each timestamp may be temporarily stored in the analog domain using analog storage elements (e.g., capacitors, inductors). Figure 2As shown in , for example, a LIDAR system may include a total of 13 analog storage elements to maintain these timestamps (e.g., from t0 to t12). It should be appreciated that the number of analog storage elements and the specific values ​​of the associated thresholds may be determined based on the characteristics of the received signal and the operating requirements of the system. The goal is to minimize the data traffic required for subsequent digital conversion while ensuring high-fidelity time information for accurate distance measurement. Depending on the specific application and operating requirements, the actual number of storage elements may be more or less than 13.

[0053] It will be appreciated that the utilization of multiple thresholds enhances the ability of the LIDAR system to interpret complex signal patterns, thereby increasing both the sensitivity and adaptability of the system. This approach enables the LIDAR system to capture complex details about the received optical signal, such as its shape, width, peak and center, and / or the like. In certain embodiments, the LIDAR system may determine the distance to the target object based on the round-trip time it takes for the optical signal to return and the known speed of light in a relevant medium, such as air. For example, such a ToF calculation may determine the pulse width of the received optical signal using a timestamp associated with a first threshold crossing on a rising edge, such as t0, and a timestamp associated with a second threshold crossing on a falling edge, such as t2.

[0054] Figure 3 308 is a simplified diagram illustrating a signal processing scheme of a LIDAR system 300 according to an embodiment of the present technology. This diagram provides an example only, which should not unduly limit the scope of the claims. A person of ordinary skill in the art will recognize many variations, substitutions, and modifications. The LIDAR system 300 may include one or more comparators with adjustable thresholds. In some embodiments, the LIDAR system 300 includes a comparator 302 and a comparator 308. The comparator 302 may be associated with a first threshold and the comparator 308 may be associated with a second threshold. The comparator 302 may be configured to receive a first electrical signal represented as SigRx and generate a second electrical signal by comparing the first electrical signal with the first threshold. The comparator 308 may be configured to receive a first electrical signal and generate a third electrical signal by comparing the first electrical signal with the second threshold.

[0055] Depending on the application, the first and second thresholds (respectively denoted as X th,高 and X th，低 ) can be adjusted dynamically. For example, the LIDAR system 300 further includes a circuit 312 (such as the fourth circuit described in claim 9) configured to adjust the first threshold and / or the second threshold. In an example, the first threshold is greater than the second threshold. Figure 3 As shown in FIG. 1 , the first threshold is denoted as X th，高 , and the second threshold is represented by X th，低In operation, the circuit 312 is configured to increase the first threshold when the first electrical signal SigRx crosses the first threshold in the rising direction and to decrease the second threshold when the first electrical signal SigRx crosses the second threshold in the falling direction. The dynamic adjustment of the threshold effectively broadens the range of detectable signal changes without the need for additional comparators, thereby enhancing performance while minimizing system complexity.

[0056] As with LIDAR system 100, system 300 may further include a filter 304 coupled to comparator 302 and a filter 310 coupled to comparator 308. For example, filter 304 is configured to generate a fourth electrical signal based on at least the second electrical signal. Filter 310 is configured to generate a fifth electrical signal based on at least the third electrical signal. Filter 304 and filter 310 may identify an event in which the input signal crosses a certain threshold (e.g., first and second thresholds) in a particular direction (e.g., an ascending or descending direction) and generate an output based on this determination. In some embodiments, the fourth and fifth electrical signals contain time information associated with the detected event. For example, the fourth electrical signal includes a first pulse that includes a first point associated with a first timestamp. The fifth electrical signal includes a second pulse that includes a second point associated with a second timestamp.

[0057] In various implementations, system 300 further includes circuit 306 coupled to filter 304 and circuit 314 coupled to filter 310. For example, circuit 306 is configured to generate a sixth electrical signal based at least on the first pulse. Circuit 314 is configured to generate a seventh electrical signal based at least on the second pulse. Memory 316 may be coupled to circuit 306 and circuit 314 and receive the sixth electrical signal and the seventh electrical signal. For example, memory 316 may include one or more analog storage elements (e.g., capacitors or inductors) and be configured to store the first and second timestamps in the analog domain.

[0058] Depending on the implementation, the timestamps saved in the memory 316 may be further evaluated or processed in the analog domain or may remain stored for subsequent digitization. In some cases, at the beginning of each cycle (when the beam is activated), the control module 318 may generate a start signal to reset the stored timestamps at the memory 316. In various examples, the timestamps stored at the memory 316 may be read by the control module 318 and processed by the signal processing unit 320 for further processing and analysis (e.g., digital conversion, ToF calculation, etc.). For example, the signal processing unit 320 includes an analog-to-digital converter (ADC) that is configured to generate a digital representation of the received signal.

[0059] Figure 44 is a simplified diagram illustrating a simulated implementation of a signal processing scheme for a LIDAR system 400 according to an embodiment of the present technology. This diagram provides an example only, which should not unduly limit the scope of the claims. Those of ordinary skill in the art will recognize many variations, substitutions, and modifications.

[0060] In various embodiments, the LIDAR system 400 includes a comparator 402 configured to receive a first electrical signal Vsig and generate a second electrical signal by comparing the first electrical signal Vcmp with a first threshold value Vref. The comparator 402 may be coupled to a filter 404 and output the second electrical signal to the filter 404. The filter 404 may be configured to distinguish the received signal from the noise to ensure that only true signal pulses contribute to the timestamp process for ToF calculation. For example, the filter 404 is configured to determine the minimum duration on the input signal (e.g., the second electrical signal Vsig) to filter out transient pulses (e.g., caused by noise interference). The filter 404 may also identify an event in which the input signal crosses a certain threshold value (e.g., a first threshold value) in a specific direction (e.g., a rising or falling direction) and generate a third electrical signal based on this determination. For example, the third electrical signal includes a falling pulse in response to the first electrical signal being lower than the first threshold value and / or a rising pulse in response to the first electrical signal being higher than the first threshold value. In some cases, the third electrical signal may contain time information (e.g., a timestamp) associated with the detected event.

[0061] In various implementations, filter 404 is coupled to circuit 406 configured to receive the third electrical signal. Circuit 406 may further include one or more analog storage elements (e.g., capacitors) configured to store time information in the analog domain. For example, circuit 406 includes a plurality of capacitors (denoted as C0 to C1). N ), which is configured to store time information. These capacitors are connected by a constant current I C The voltage output from these capacitors (denoted as V Cx ) is proportional to the timestamp according to the following equation:

[0062]

[0063] where t x The capacitor is represented by the current I C The duration of charging.

[0064] In some embodiments, circuit 406 further includes a plurality of cascaded RS flip-flops (e.g., RS flip-flops 408a, 408b, 408c) configured to ensure that different stages of circuit 406 respond to rising and falling pulses in a sequential manner. This sequencing is achieved by deactivating the individual current sources after the transition of each stage, thereby producing a controlled sequential response. Each operation cycle is initiated by a reset signal labeled "res", which discharges the capacitor through its corresponding metal oxide semiconductor field effect transistor (MOSFET) denoted as Mr and resets the RS flip-flop chain. After the light beam is emitted or any other initiation event, the "res" signal is released. Thereafter, the capacitor begins to accumulate with a constant current I C After detecting the first pulse, the RS flip-flop at stage 0 changes its state, causing the charging current M C deactivates. Thus, the voltage across capacitor C0 becomes proportional to the time elapsed between the falling edge of "res" and the occurrence of the "rising" of the first pulse. The output of this first RS flip-flop further deactivates the subsequent stage, allowing it to respond to the next detected pulse, and so on. This sequence allows the acquisition and storage of timestamps for up to N events in a sequential manner. The number of such storage elements, denoted N, can vary according to the requirements of a particular application. In various embodiments, the storage elements may be stored via a plurality of storage elements, denoted M. O and M S The combination of a MOSFET and a bias current source is used to perform the readout of the stored timestamp.

[0065] Figure 5 5 is a simplified diagram of a simulated implementation of a signal processing scheme for a LIDAR system 500 according to an embodiment of the present technology. This diagram provides an example only, which should not unduly limit the scope of the claims. A person of ordinary skill in the art will recognize many variations, substitutions, and modifications.

[0066] In various embodiments, the reception of optical signals in a LIDAR system, particularly when the timestamps are based on singular threshold crossing points, can produce a time output that is susceptible to variations in the slew rate or bandwidth of the received optical signal. This is particularly relevant when the threshold level used to capture the timestamps remains static, which can lead to systematic errors caused by different external factors (e.g., target reflectivity) or weather conditions (e.g., rain or fog). To address this challenge, the LIDAR system 500 implements a mechanism that is capable of capturing a timestamp associated with the peak of a pulse to compensate for the errors caused by the aforementioned slew rate variations.

[0067] In some embodiments, circuit 502 receives a signal from a filter (eg, Figure 4The filter 404 of the circuit 502 receives an input electrical signal. The input electrical signal may include a first pulse, which includes a first point associated with a first timestamp and a second point associated with a second timestamp. For example, the first timestamp indicates when the first pulse crosses a threshold in an ascending direction, and the second timestamp indicates when the first pulse crosses the threshold in a descending direction. The circuit 502 may be configured to calculate a third timestamp associated with a third point of the first pulse. The third point may be located between the first point and the second point. In some cases, the third point is a peak point of the first pulse.

[0068] In operation, a control signal denoted as AVG may be activated to close an associated switch (eg, switches 504, 506, etc.), which activates a plurality of capacitors C0 to C N . For example, activation of control signal AVG may be controlled by a control module (not shown). When equal-sized capacitors are employed, charge redistribution results in an average voltage representing a timestamp (e.g., the third timestamp) associated with the peak point of the first pulse, thereby allowing the circuit to effectively "look back" in time. By evaluating the average of two time measurements (e.g., the first and second timestamps), the LIDAR system 500 effectively captures a more accurate and environmentally adaptive set of timestamps, thereby improving the robustness and accuracy of the system under various operating conditions.

[0069] Figure 6 6 is a simplified diagram illustrating a filter of a LIDAR system 600 according to an embodiment of the present technology. This diagram is provided merely as an example, which should not unduly limit the scope of the claims. One of ordinary skill in the art will recognize many variations, substitutions, and modifications. In various implementations, the LIDAR system 600 may employ a comparator system configured to provide a filter based on the slew rate characteristic of the input signal (denoted as V SIG ) for selective event detection. The term "slew rate" may refer to the maximum rate of change of signal amplitude over time. As an example, LIDAR system 600 includes a first comparator 602 and a second comparator 604. The first comparator 602 may be connected to a second comparator 604 represented by X th,arming The second comparator 604 may be associated with a first threshold value represented by X th，事件 is associated with a second threshold value of .

[0070] In operation, the second threshold value can be configured to be lower than the first threshold value, which ensures that when the input electrical signal V SIG The second comparator responds first when . Therefore, the first output signal (denoted as EV) generated by the second comparator 604 can be output to the circuit 606. The circuit 606 is configured to determine the minimum duration τ on the input signal 事件 According to an embodiment, the minimum duration τ 事件The first comparator 602 is configured to compare the input signal V SIG The second output signal may be output to circuit 608, which may include a D-type flip-flop. Circuit 608 may be output from the output of circuit 606 (denoted as EV dτ ) timing. This arrangement ensures that the output of circuit 608 will only be displayed when the slew rate of the input signal is within the specified time frame τ 事件 The voltage difference (X th,arming -X th,事件 ). Although this document describes a two-point architecture for ease of understanding and simplicity, it should be understood that the design of the system advantageously supports slew rate detection at multiple points beyond the two points illustrated, thereby providing a more comprehensive analysis of signal characteristics. The LIDAR system 600 provides an effective mechanism for dynamically selecting signals based on their slew rate. This effectively filters input signals by allowing only input signals that meet specific slew rate conditions to pass, thereby improving the accuracy and reliability of the LIDAR system 600 under different environmental conditions.

[0071] While the above is a complete description of specific embodiments, various modifications, alternative constructions, and equivalents may be used. Therefore, the above description and illustrations should not be taken as limiting the scope of the present technology, which is defined by the appended claims.

Claims

1. A device comprising: an optical module configured to receive a first optical signal; a first circuit coupled to the optical module, the first circuit configured to generate a first electrical signal based at least on the first optical signal; a first comparator coupled to the first circuit, the first comparator configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter coupled to the first comparator, the first filter configured to generate a signal based on at least the the second electrical signal produces a third electrical signal, the third electrical signal comprising a first pulse, the first pulse comprising a first point associated with a first timestamp; a second circuit coupled to the first filter, the second circuit configured to generate a fourth electrical signal based at least on the first pulse; and A memory is configured to receive the fourth electrical signal and store the first timestamp. 2 . The device of claim 1 , further comprising a second comparator coupled to the first circuit, the second comparator configured to compare the first electrical signal with a second threshold.

3. The device of claim 2, further comprising a second filter coupled to the second comparator. The device of claim 1 , wherein the memory comprises a capacitor or an inductor.

5. The device of claim 1, further comprising a third circuit coupled to the memory, the third circuit configured to read the first timestamp and send a first signal to the second circuit to reset the memory. The apparatus of claim 1 , wherein the first pulse comprises a rising pulse in response to the first electrical signal being higher than the first threshold. 7 . The device of claim 1 , wherein the first pulse comprises a falling pulse in response to the first electrical signal being lower than the first threshold.

8. The device of claim 1, wherein the first filter is configured to determine a width of the first pulse.

9. The device of claim 1, further comprising a fourth circuit coupled to the first comparator, the fourth circuit configured to adjust the first threshold.

10. The device of claim 1, wherein the fourth electrical signal comprises an analog signal.

11. An apparatus comprising: an optical module configured to receive a first optical signal; a first circuit coupled to the optical module, the first circuit configured to generate a first electrical signal based at least on the first optical signal; a first comparator coupled to the first circuit, the first comparator configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter coupled to the first comparator, the first filter configured to generate a signal based on at least the the second electrical signal produces a third electrical signal, the third electrical signal comprising a first pulse, the first pulse comprising a first point associated with a first timestamp; a second circuit coupled to the first filter, the second circuit configured to generate a fourth electrical signal based at least on the first pulse; and A memory coupled to the second circuit is configured to receive the fourth electrical signal and store the first timestamp.

12. The device according to claim 11, further comprising: a second comparator coupled to the first circuit, the second comparator being configured to generate a fifth electrical signal by comparing the first electrical signal with a second threshold; and A second filter is coupled to the second comparator, the second filter being configured to generate a sixth electrical signal based at least on the fifth electrical signal, the sixth electrical signal comprising a second pulse, the second pulse comprising a second point associated with a second timestamp.

13. The device of claim 12, further comprising a fourth circuit coupled to the second filter, the fourth circuit configured to generate a seventh electrical signal based at least on the second pulse.

14. The device of claim 13, wherein the memory is coupled to the fourth circuit, and the memory is configured to receive the seventh electrical signal and store the second timestamp.

15. The device of claim 11, further comprising a fifth circuit coupled to the first comparator, the fifth circuit configured to adjust the first threshold.

16. An apparatus comprising: an optical module configured to receive a first optical signal; a first circuit coupled to the optical module, the first circuit configured to generate a first electrical signal based at least on the first optical signal; a first comparator coupled to the first circuit, the first comparator configured to generate a second electrical signal by comparing the first electrical signal with a first threshold; a first filter coupled to the first comparator, the first filter configured to generate a signal based on at least the The second electrical signal generates a third electrical signal, the third electrical signal includes a first pulse, the first pulse includes a first point and a second point, the first point is associated with a first timestamp, and the second point is associated with a second timestamp; a second circuit coupled to the first filter, the second circuit configured to generate a fourth electrical signal based at least on the first pulse; and A memory is configured to receive the fourth electrical signal and store a third timestamp based on at least the first timestamp and the second timestamp.

17. The apparatus of claim 16, wherein the first pulse further comprises a third point located between the first point and the second point, the third point being associated with the third timestamp.

18. The apparatus of claim 16, wherein the memory comprises a capacitor or an inductor.

19. The device of claim 16, further comprising a third circuit coupled to the memory, the third circuit configured to read the third timestamp.

20. The apparatus of claim 16, wherein the fourth electrical signal comprises an analog signal.

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