Process voltage and time invariant compensation loop for high precision propagation delay in multi-channel LIDAR applications

Abstract

The invention relates to a process voltage and time invariant compensation loop for high precision propagation delay in multi-channel LIDAR applications. Electronic systems and methods for generating pulsating lighting signals in multi-channel LIDAR applications are provided. An example electronic system includes a pulse signal generator, a pulse transmission circuit, and an illumination source. The pulsation signal generator includes a main switch, a selection switch that controls a flow of current to the illumination source, and a switch control circuit. The switch control circuit is configured to receive an illumination source enable signal indicative of a difference between a duration of the illumination source enable signal and a target duration of the illumination source enable signal. The switch control circuit is configured to receive the duration target code and determine a main switch enable signal configured to activate the main switch and a select switch enable signal configured to activate the select switch based at least in part on the duration target code and the target overlap.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to a propagation loop that performs high-precision timing in multi-channel light detection and ranging (LIDAR) applications, and more particularly to a process voltage and time (PVT) invariant propagation loop for high-precision, multi-channel LIDAR applications. Background Art

[0002] Various example embodiments address technical problems associated with generating electronic pulse signals to power laser diodes, particularly in multi-channel LIDAR applications. In general, multi-channel LIDAR applications include multiple laser diodes for generating very short (approximately 1 nanosecond), high current (up to 40 amps each) pulses. These pulses are directed by an optical system that typically includes two micro-electromechanical (MEMS) mirrors for scanning horizontally and vertically toward a target environment. The system also includes a receiver (e.g., a single photon avalanche diode) positioned to receive the pulses when they are reflected from various obstacles in the environment. Receipt of the pulses enables the system to measure the time of flight (ToF) of the pulses and determine the obstacle distance, thereby enabling the system to reconstruct a 3D image of the target environment.

[0003] Applicants have discovered many technical challenges and difficulties associated with generating pulsed lighting signals.Through hard work, ingenuity and innovation, Applicants have solved the problems associated with generating high precision and PVT invariant pulsed lighting signals, which are described in detail below. Summary of the invention

[0004] Embodiments are directed to example systems and methods for generating pulsed illumination signals in multi-channel LIDAR applications. According to some embodiments of the present disclosure, an example electronic system is provided. In some embodiments, the example electronic system may include a pulse emission circuit electrically connected to an illumination source. The example electronic system may also include a pulse signal generator. In some embodiments, the pulse signal generator may include a main switch electrically connected to the pulse emission circuit, a selection switch electrically connected to the main switch, and a switch control circuit. In some embodiments, the selection switch controls the flow of current to the illumination source. In some embodiments, the switch control circuit may include a first control circuit, wherein the first control circuit receives an illumination source enable signal indicating a state of the illumination source, and wherein the first control circuit generates a duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration of the illumination source enable signal. In addition, in some embodiments, the switch control circuit may include a second control circuit, wherein the second control circuit receives a duration target code, and wherein the second control circuit determines a main switch enable signal configured to activate the main switch and a selection switch enable signal configured to activate the selection switch based at least in part on the duration target code and the target overlap.

[0005] In some embodiments, the first control circuit of the switch control circuit may further include a first time-to-digital converter (TDC), wherein the first TDC is configured to determine an illumination signal offset between a duration of the illumination source enable signal and a target duration of the illumination source enable signal.

[0006] In some embodiments, the first control circuit may further include a first proportional-integral-derivative controller configured to generate a duration target code based on the illumination signal offset.

[0007] In some embodiments, the second control circuit further comprises a second time-to-digital converter (TDC) configured to determine a select signal offset, wherein the select signal offset represents a time difference between a target overlap and an overlap of the select switch state signal and the main switch state signal. In some embodiments, the select switch state signal may be based at least in part on the select switch enable signal. In some embodiments, the main switch state signal is based at least in part on the main switch enable signal.

[0008] In some embodiments, the second control circuit may further include a second proportional-integral-derivative controller configured to generate an overlapping target code based on the selection signal offset.

[0009] In some embodiments, the second control circuit may further include an illumination signal off programmable delay line configured to generate an illumination off signal based on the overlap target code and the target overlap.

[0010] In some embodiments, the second control circuit may de-assert the select switch enable signal based on the lighting off signal.

[0011] In some embodiments, the electronic system may further include a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch.

[0012] In some embodiments, the second control circuit may be a cascade of the first control circuit such that adjustments to the duration target code do not affect the overlap target code, and adjustments to the overlap target code do not affect the duration target code.

[0013] An example method for generating a pulsating illumination signal is also provided. In some embodiments, the example method may include receiving a pulsating electronic signal at a pulsating signal generator, and receiving an illumination source enable signal at the pulsating signal generator from an illumination source indicating a state of the illumination source. The method may also include generating a duration target code at a first control circuit based at least in part on the illumination source enable signal, the duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration of the illumination source enable signal. The method may also include receiving the duration target code at a second control circuit. In some embodiments, the method may include determining at the second control circuit a main switch enable signal configured to activate a main switch, and determining at the second control circuit a select switch enable signal based at least in part on the duration target code and a target overlap with the main switch enable signal. In some embodiments, the select switch enable signal may be configured to activate a select switch, and the select switch may cause current to flow to the illumination source. In some embodiments, the method may include generating the pulsating illumination signal based at least in part on the select switch enable signal.

[0014] In some embodiments, the method may further include determining, at a first time-to-digital converter (TDC) of the first control circuit, an illumination signal offset between a duration of the illumination source enable signal and a target duration of the illumination source enable signal.

[0015] In some embodiments, the method may further include receiving, at the first proportional-integral-derivative controller, an illumination signal offset; and generating a duration target code based on the illumination signal offset.

[0016] In some embodiments, the method may further include receiving a select switch state signal and a main switch state signal at a second time-to-digital converter of a second control circuit, wherein the select switch state signal is based at least in part on the select switch enable signal, and wherein the main switch state signal is based at least in part on the main switch enable signal. In some embodiments, the method may further include determining a select signal offset based at least in part on a time difference between a target overlap and an overlap of the select switch state signal and the main switch state signal.

[0017] In some embodiments, the method may further include receiving a select signal offset at a second proportional-integral-derivative controller of the second control circuit, and generating an overlapping target code based at least in part on the select signal offset.

[0018] In some embodiments, the method may further include receiving an overlap target code and a target overlap at an illumination signal off programmable delay line of the second control circuit, and generating an illumination off signal based at least in part on the overlap target code and the target overlap.

[0019] In some embodiments, the method may further include de-asserting a select switch enable signal based at least in part on the lighting off signal.

[0020] In some embodiments, the pulsation signal generator may further include a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch.

[0021] In some embodiments, the second control circuit may be a cascade of the first control circuit such that adjustments to the duration target code do not affect the overlap target code, and adjustments to the overlap target code do not affect the duration target code.

[0022] An example light detection and ranging (LIDAR) system is also provided. In some embodiments, the example LIDAR system may include a controller, a pulse emission circuit electrically connected to the controller, and an illumination source, wherein the illumination source is configured to generate a light output based at least in part on an illumination source enable signal. In some embodiments, the example LIDAR system may include a pulsating signal generator. The pulsating signal generator may include a main switch electrically connected to the pulse emission circuit, a selector switch electrically connected to the main switch, and a switch control circuit. In some embodiments, the selector switch may control the flow of current to the illumination source. In some embodiments, the switch control circuit may include a first control circuit and a second control circuit. In some embodiments, the first control circuit may receive an illumination source enable signal indicating a state of the illumination source, and generate a duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration of the illumination source enable signal. In some embodiments, the switch control circuit may include a second control circuit, wherein the second control circuit may receive the duration target code, and determine a main switch enable signal configured to activate the main switch and a selector switch enable signal configured to activate the selector switch based at least in part on the duration target code and the target overlap. In some embodiments, the example LIDAR system may further include a transmit pulse receiver electrically connected to the controller and configured to receive reflections of the light output from the object. In some embodiments, the controller may be configured to determine the distance of the object based on the reflections of the light output.

[0023] In some embodiments, the pulsation signal generator may further include a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Reference will now be made to the drawings. The components shown in the drawings may or may not be present in certain embodiments described herein. According to example embodiments of the present disclosure, some embodiments may include fewer (or more) components than shown in the drawings.

[0025] Figure 1 A block diagram of an example electronic system including a pulsating signal generator is illustrated according to one or more embodiments of the present disclosure.

[0026] Figure 2 Depicted are example currents flowing through an example four-channel pulsed lighting generator circuit according to example embodiments of the present disclosure.

[0027] Figure 3 Illustrated are circuit level diagrams of example pulse emission circuits, main switch circuitry, select switch circuitry, and illumination source circuitry according to example embodiments of the present disclosure.

[0028] Figure 4Depicted is a block diagram of an example switch control circuit according to an example embodiment of the present disclosure.

[0029] Figure 5 A circuit level diagram of an example first control circuit of an example switch control circuit according to an example embodiment of the present disclosure is illustrated.

[0030] Figure 6 A circuit level diagram of an example second control circuit of an example switch control circuit according to an example embodiment of the present disclosure is illustrated.

[0031] Figure 7 Depicted is a circuit-level diagram of an example electronic system including a pulsating signal generator for multi-channel LIDAR applications, according to one or more embodiments of the present disclosure.

[0032] Figure 8 Depicted is an example signal diagram of an example pulsating signal generator for a multi-channel LIDAR application in accordance with one or more embodiments of the present disclosure.

[0033] Fig. 9 An example flow chart of a method for generating a pulsed lighting signal according to one or more embodiments of the present disclosure is depicted.

[0034] Fig.10 Depicted is an example block diagram of an example LIDAR application including a pulsation signal generator in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0035] Example embodiments will be described more fully below with reference to the accompanying drawings, which show some, but not all, embodiments of the invention of the present disclosure. Indeed, the embodiments of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure satisfies applicable legal requirements. Throughout the text, like reference numerals represent like elements.

[0036] As used herein, the term "high" when referring to a voltage indicates that the identified voltage is above a certain minimum voltage threshold of the electronic device, typically between 1.8 volts and 3.6 volts. Similarly, the term "low" when referring to a voltage indicates that the identified voltage is below a certain voltage threshold of the electronic device, typically at or near 0 volts.

[0037] Each example embodiment solves technical problems associated with generating electronic pulse signals to power laser diodes configured to generate pulsed illumination signals, particularly in multi-channel LIDAR applications. In general, multi-channel LIDAR applications include multiple laser diodes for generating very short (approximately 1 nanosecond), high current (up to 40 amps each) pulses. These pulses are directed by an optical system, which typically includes two micro-electromechanical (MEMS) mirrors for horizontal and vertical scanning toward a target environment. The system also includes a receiver (e.g., a single photon avalanche diode) positioned to receive the pulses when they are reflected from various obstacles in the environment. Receipt of the pulses enables the system to measure the time of flight (ToF) of the pulses and determine the obstacle distance, thereby enabling the system to reconstruct a 3D image of the target environment.

[0038] In some embodiments, in order to reduce the required resonant peak current generated by the pulse emission circuit (e.g., LC circuit), each laser diode generates pulses in sequence rather than simultaneously. The sequential activation of multiple laser diodes can be achieved through a series of selection switches. In some embodiments, the main switch can control the activation and deactivation of the resonant cycle of the signal generated by the pulse emission circuit. Once the resonant cycle begins and the current through the switching mechanism ramps up, the main switch "transfers" current from the main switch to each selection switch during the peak resonant current of the signal generated by the pulse emission circuit. Between the activation of each selection circuit, the current is switched back to the main switch. Typically, gallium nitride (GaN) switches are used to drive each of these laser diodes because GaN switches can be turned on and off quickly, thereby supporting higher frequency, higher precision switching.

[0039] In order to guarantee a continuous path for the resonant current, a certain amount of overlap time must be guaranteed between when the main switch is activated and when each select switch is deactivated. However, the overlapping pulses at the end of the select switch pulses must be reduced to a minimum to speed up the laser shutoff. The faster the laser is turned off, the more precise the pulsed illumination signal is, and the more accurate the mapping of the target environment based on the received reflections is. In order to precisely control the amount of overlap, the system must account for response delays. For example, the delay between the time the switch driver sends a command to open or close the main switch or select switch and the time the switch actually closes. In addition, delays can occur between the moment the switch is turned on / off and the moment the laser pulse is enabled / disabled. To complicate matters, delays within the system can be temperature dependent.

[0040] One method for controlling gate delays at different operating temperatures is to compensate for timing variations by inserting a programmable delay chain on the path that provides signals to the illumination source circuitry. In such an embodiment, each device is calibrated at different temperatures. The results for each temperature can then be stored in non-volatile memory, and the delay chain can be programmed for each temperature during operation based on a table stored in the non-volatile memory. Disadvantages of this solution include an increase in the total calibration time and cost of testing each system at each temperature. In addition, the calibration table may need to be updated over time due to aging of the system and system components.

[0041] The example embodiments described herein utilize various techniques to provide high-precision and PVT-invariant synchronization between a main switch and multiple select switches in a multi-channel LIDAR application.

[0042] For example, in some embodiments, in order to control the synchronization of the main switch with each select switch, two digital control circuits are implemented within the switch control circuit of the pulse signal generator: a laser pulse duration digital control circuit and a select switch activation digital control circuit.

[0043] Generally speaking, the laser pulse duration digital control circuit compares the pulse width of the pulsed illumination signal of the connected laser diode and determines any adjustments that can be made to align the pulse width duration of the pulsed illumination signal with a target pulse width duration. The laser pulse duration digital control circuit can detect the time difference between the time when the laser diode is turned off and the expected time when the laser diode is turned off based on the target pulse width duration. The laser diode off signal can then be adjusted to align the time when the laser is turned off with the expected time when the laser is turned off. The result of the laser pulse duration digital control circuit is a duration target code that indicates the delay required to obtain the target pulse width of the pulsed illumination signal.

[0044] The select switch activation digital control circuit can monitor the gate voltages of the main switch and the select switch, for example, to detect and adjust for the time difference between the moment when the main switch is enabled and the moment when the select switch is disabled. In practice, the smaller the overlap between deactivating the select switch and activating the main switch, the faster the laser diode connected to the select switch can be turned off. In addition, the faster the laser diode can be turned off, the more accurate the measurement based on the reflection of the pulsed illumination signal.

[0045] Furthermore, because a PVT-invariant reference clock is used in determining the duration target code and each of the main switch and select switch enable and disable signals, the pulsating signal generator can be PVT-invariant. This alleviates the need for complex calibration to determine the operation of circuit components at different temperatures and process voltages.

[0046] Through the example embodiments described herein and in some examples, the effectiveness and accuracy of the pulsation signal generator on the multi-channel LIDAR system can be greatly improved. In addition, due to the PVT invariance of the pulsation signal generator, the initialization of the circuit can be greatly simplified.

[0047] Reference now Figure 1 , provides an example block diagram of an example pulsating lighting generator circuit 100. Figure 1 As depicted in FIG. 1 , the example pulsed illumination generator circuit 100 includes a pulse emission circuit 102 electrically connected in series to a pulse signal generator 124 and an illumination source circuit system 108. Figure 1 As further depicted in FIG. 1 , the pulsation signal generator 124 includes a main switch circuit system 104 electrically connected in parallel with a selection switch circuit system 106. The pulsation signal generator 124 also includes a switch control circuit 110 configured to receive a status signal (e.g., a main switch status signal 112) from the electrically connected main switch circuit system 104 and a status signal (e.g., a lighting source enable signal 116) from the electrically connected lighting source circuit system 108. Figure 1 , the switch control circuit 110 is also configured to generate a main switch enable signal 118 that is transmitted to the main switch circuit system 104, and a select switch enable signal 120 that is transmitted to the select switch circuit system 106. Upon receiving the select switch enable signal 120, the select switch circuit system 106 may transmit a pulsed illumination signal 122 to the illumination source circuit system 108, thereby causing the illumination source circuit system 108 to generate a pulsed illumination output 126. The select switch circuit system 106 may also provide a select switch state signal 114 that indicates the state of the select switch circuit system 106.

[0048] like Figure 1 As depicted in , the example pulsed illumination generator circuit 100 includes a pulse emission circuit 102. The pulse emission circuit 102 can be any resonant circuit configured to generate an oscillating current at a specific resonant frequency, including hardware, software, firmware, or a combination thereof. In some embodiments, the pulse emission circuit 102 can include an LC circuit or a tank circuit. In some embodiments, such as multi-channel LIDAR applications, the current generated by the pulse emission circuit 102 can be used to drive one or more illumination sources, for example, a laser diode included in the example illumination source circuit system 108.

[0049] like Figure 1As further depicted in FIG. 1 , the pulsed illumination generator circuit 100 includes a pulsed signal generator 124 connected in series with the pulse emission circuit 102 and the illumination source circuit system 108. The depicted pulsed signal generator 124 includes a main switch circuit system 104 electrically connected in parallel with the selection switch circuit system 106. As depicted, the main switch circuit system 104 may include hardware, firmware, software, or any combination thereof configured to switch the current provided by the pulse emission circuit 102 through the main switch circuit system 104. For example, in some embodiments, the main switch circuit system 104 may include a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), or another transistor / switch device and accompanying circuit system. In some embodiments, the main switch circuit system 104 may include a gallium nitride (GaN) switch, thereby enabling faster switching speeds, higher operating frequencies, and high power applications.

[0050] The depicted pulsation signal generator 124 also includes a selection switch circuit system 106 electrically connected in parallel with the main switch circuit system 104. The selection switch circuit system 106 may include hardware, firmware, software, or any combination thereof configured to switch the current provided by the pulse transmission circuit 102 through the selection switch circuit system 106. For example, in some embodiments, the selection switch circuit system 106 may include a MOSFET, a bipolar junction transistor BJT, or another transistor / switch device and accompanying circuit system. In some embodiments, the selection switch circuit system 106 may include a GaN switch, thereby enabling faster switching speeds, higher operating frequencies, and high power applications.

[0051] Generally speaking, the main switch circuit system 104 and the select switch circuit system 106 cooperate to control the flow of current generated by the pulse transmission circuit 102 through the pulse signal generator 124. Now referring to Figure 2 , graph 200 depicts an example current flow through an example four-channel pulsed lighting generator circuit 100 including a pulse signal generator 124. Figure 2 , the pulse transmission circuit 102 generates an oscillating current 212 having a voltage 214. To obtain an accurate distance measurement, the pulsed illumination generator circuit 100 may wait until the oscillating current 212 reaches a certain threshold current before generating the pulsed illumination output 126.

[0052] like Figure 2, in the case where the main switch circuit system 104 is enabled (as depicted by the main switch enable 202), current flows through the main switch circuit system 104. Therefore, the main switch enable 202 remains high until the oscillating current 212 reaches a certain minimum threshold current. In the case where the oscillating current 212 reaches a certain minimum threshold current, the main switch enable 202 is disabled and the select switch 1 enable 204 is enabled, thereby allowing current to flow through the select switch circuit system 106 (e.g., switch 1 current 216) and the illumination source circuit system 108, thereby generating the pulsating illumination output 126.

[0053] like Figure 2 As shown in , in a multi-channel LIDAR application, multiple channels can be sequentially enabled by switching the oscillating current 212 from the main switch circuit system 104 (e.g., the main switch enable 202 is enabled) to the selection switch circuit system 106 (e.g., the selection switch 1 enable 204 is enabled) and the associated illumination source, then switching back to the main switch circuit system 104, then switching to the next selection switch in the selection switch circuit system 106 (e.g., the selection switch 2 enable 206 is enabled) and the associated illumination source, and so on. Therefore, the selection switch 1 enable 204, the selection switch 2 enable 206, the selection switch 3 enable 208, and the selection switch 4 enable 210 are all asserted in a single oscillation of the oscillating current 212, thereby enabling current to flow through each selection switch in the selection switch circuit system 106, as evidenced by the switch 1 current 216, the switch 2 current 218, the switch 3 current 220, and the switch 4 current 222, thereby generating a pulsating illumination output 126 from the illumination source associated with each switch.

[0054] In some multi-channel LIDAR applications, the pulsating illumination generator circuit can support a variable number of channels. For example, given a particular hardware configuration, the pulsating illumination generator circuit can support a maximum number of channels (e.g., four transmission channels). However, during operation, the multi-channel LIDAR application can change the number of enabled transmission channels. For example, when an object is detected at a close distance, one transmission channel can be enabled, while when an object is detected at a long distance, all four transmission channels can be enabled. Even different numbers of transmission channels can be enabled depending on the position in the scene. In this case, the number of transmission channels enabled during a single oscillation of the oscillating current 212 can vary during operation. In this case, the timing can be updated to support a variable number of transmission channels.

[0055] Now return to Figure 1, the example pulsed illumination generator circuit 100 also includes an illumination source circuit system 108. The illumination source circuit system 108 may include an illumination source and associated circuit systems configured to generate a pulsed illumination output 126 upon receiving the pulsed illumination signal 122. The illumination source may include any light source, such as a laser diode, a light emitting diode, or other similar source configured to output light. In some embodiments, the illumination source may include a semiconductor laser diode, for example, a vertical cavity surface emitting laser (VCSEL) and / or an edge emitting laser diode. In general, the illumination source may output a coherent light beam upon receiving an electric current (such as an oscillating current generated by the pulse emission circuit 102). In LIDAR applications, the illumination source may be provided by generating a pulsed illumination output 126, receiving reflected pulsed illumination (e.g., such as Fig.10 The distance of objects in the environment is measured by using the reflected pulsed illumination 1006 shown in FIG. 1 and determining the time of flight of the pulsed illumination output 126.

[0056] like Figure 1 As further depicted in FIG. 1 , the example pulsating signal generator 124 includes a switch control circuit 110 configured to receive electrical data from the main switch circuit system 104 (e.g., the main switch state signal 112), the electrical data of the selection switch circuit system 106 (e.g., the selection switch state signal 114), and the electrical data of the lighting source circuit system 108 (e.g., the lighting source enable signal 116) to generate a main switch enable signal 118 and a selection switch enable signal 120. The pulsating signal generator 124 can be any hardware, firmware, software, or combination thereof configured to determine a switching sequence of one or more switches of the main switch circuit system 104 and the selection switch circuit system 106 including the pulsating lighting generator circuit 100, and as shown in FIG. Figure 3-Figure 8 Further described in .

[0057] like Figure 1As further depicted in , the example switch control circuit 110 can exchange electrical signals with the main switch circuit system 104. In some embodiments, the main switch circuit system 104 can generate and transmit a main switch state signal 112. The main switch state signal 112 can be any signal indicating the state of the main switch circuit system 104. For example, the main switch state signal 112 can indicate: whether the main switch within the main switch circuit system 104 is open, thereby preventing current from passing through the main switch circuit system 104; or closed, thereby allowing current to pass through the main switch circuit system 104. In some embodiments, the main switch state signal 112 can be generated at least in part based on the voltage between the gate and the source of the switching device (e.g., MOSFET, BJT) that includes the main switch circuit system 104. For example, the main switch state signal 112 can be generated by a comparator that monitors the gate-source voltage of the switching device. Similarly, a switch state signal can be generated and transmitted for each switching device in the selection switch circuit system 106.

[0058] like Figure 1 As further depicted in FIG. 1 , the switch control circuit may generate a main switch enable signal 118 and transmit the main switch enable signal 118 to the main switch circuit system 104. The main switch enable signal 118 may be any signal or series of signals that changes the state of the main switch circuit system 104. For example, in some embodiments, the main switch enable signal 118 may cause a voltage to be supplied to a gate of a switching device of the main switch circuit system 104. In some embodiments, when the main switch enable signal 118 is high, the switching device of the main switch circuit system 104 may be enabled, thereby allowing current to flow through the main switch circuit system 104, and when the main switch enable signal 118 is low, the switching device of the main switch circuit system 104 may be disabled, thereby preventing current from flowing through the main switch circuit system 104.

[0059] like Figure 1As further depicted in , the example switch control circuit 110 can receive a selection switch state signal 114 from the selection switch circuit system 106. The selection switch state signal 114 can be any signal indicating the state of the selection switch circuit system 106. For example, the selection switch state signal 114 can indicate whether the selection switch within the selection switch circuit system 106 is open, thereby preventing current from passing through a particular switch; or closed, thereby allowing current to pass through a particular switch and a corresponding lighting source. In some embodiments, the selection switch state signal 114 can be generated based at least in part on the voltage between the gate and source of a switching device (e.g., a MOSFET, a BJT) that includes the selection switch circuit system 106. For example, the selection switch state signal 114 can be generated by a comparator that monitors the gate-source voltage of the switching device. Similarly, a switch state signal can be generated and transmitted for each switching device in the selection switch circuit system 106.

[0060] like Figure 1 As further depicted in FIG. 1 , the example switch control circuit 110 may receive an illumination source enable signal 116. The illumination source enable signal 116 may be any signal that indicates a state of one or more illumination sources of the illumination source circuit system 108. For example, the illumination source enable signal 116 may indicate whether an illumination source within the illumination source circuit system 108 is turned on, thereby generating a pulsating illumination output 126, or is turned off and does not generate any pulsating illumination output 126. In some embodiments, the illumination source enable signal 116 may be generated based at least in part on a voltage at an anode of an optical illumination source (e.g., a laser diode). For example, the illumination source enable signal 116 may be generated by a comparator that monitors the anode voltage of the laser diode.

[0061] like Figure 1 As further depicted in FIG. 1 , the switch control circuit 110 may generate and transmit one or more select switch enable signals 120 to the select switch circuit system 106. The select switch enable signal 120 may be any signal or series of signals that changes the state of one or more of the select switches comprising the select switch circuit system 106. For example, in some embodiments, the select switch enable signal 120 may cause a voltage to be supplied to the gate of a switch device associated with a channel in the select switch circuit system 106. In some embodiments, when the select switch enable signal 120 is high for a particular channel switch device, the switch device may be enabled, thereby allowing current to flow through the channel of the select switch circuit (e.g., Figure 2 ) and causes the associated lighting source to generate a pulsating lighting output 126. In the event that the select switch enable signal 120 is low for a particular channel switch device, the switch device can be disabled, thereby preventing current from flowing through the channel of the select switch circuit, preventing the lighting source from generating a pulsating lighting output 126.

[0062] Reference now Figure 3 , an example embodiment of a pulsed lighting generator circuit 300 is provided. Figure 3 As depicted in FIG. 3 , the example pulsed lighting generator circuit 300 includes a pulse emission circuit 102 configured to output an oscillating current. The depicted pulse emission circuit 102 includes an LC circuit or a tank circuit, thereby utilizing a capacitor 304 and an inductor 302 to generate the oscillating current.

[0063] Figure 3 The pulse emission circuit 102 is electrically connected to the input of the pulse signal generator 124, which is then electrically connected to the illumination source circuit system 108 at one output before returning to the pulse emission circuit 102, and is directly electrically connected back to the pulse emission circuit 102 at another output.

[0064] like Figure 3 As further depicted in FIG. 1 , the pulsating signal generator 124 includes a main switch circuit system 104 and a selection switch circuit system 106. The main switch circuit system 104 of the example pulsating lighting generator circuit 300 further includes a main switch switching device 306, which is configured to receive the main switch enable signal 118 to control the flow of current through the main switch circuit system 104. Figure 3 is depicted as a MOSFET, but as Figure 1 As described, the main switch switching device 306 can be any MOSFET, bipolar junction transistor BJT, or other transistor / switch device configured to control the flow of current through the main switch circuitry 104 and back to the pulse emission circuit 102 based at least in part on the main switch enable signal 118.

[0065] like Figure 3 As further depicted in FIG. 1 , the selector switch circuit system 106 of the example pulsating lighting generator circuit 300 includes the selector switch circuit system 106, which further includes a selector switch switching device 308. Figure 3 is depicted as a MOSFET, but as Figure 1 As described, the select switch switching device 308 can be any MOSFET, bipolar junction transistor BJT, or other transistor / switch device configured to control the flow of current through the select switch circuitry 106 and the associated illumination source circuitry 108 based at least in part on the select switch enable signal 120 .

[0066] like Figure 3As further depicted in FIG. 1 , the example illumination source circuit system 108 includes a laser diode 310 configured to receive the pulsed illumination signal 122 from the selector switch device 308 and generate a pulsed illumination output 126. The laser diode 310 may be any semiconductor device configured to generate coherent light. Figure 3 As depicted in , when the associated selector switch device 308 causes current to flow through the illumination source circuit system 108, the laser diode 310 can be energized and illuminated, thereby generating a pulsed illumination output 126 including a coherent laser beam. Figure 2 As depicted, in some embodiments, an oscillating current from the pulse emission circuit 102 can be transferred between the main switch circuitry 104 and the selection switch circuitry 106 and the associated illumination source circuitry 108 to generate a high precision, short and high current pulsed illumination output 126 .

[0067] Although in Figure 3 300, but the example pulsed illumination generator circuit 300 may include multiple channels, including multiple selector switch devices 308 and associated laser diodes 310, such as Figure 7 As depicted in .

[0068] Reference now Figure 4 , provides an example switch control circuit 110 of a pulsating signal generator in a pulsating lighting generator circuit. Figure 4 , the example switch control circuit 110 includes a laser pulse duration digital control circuit 402 electrically connected to a select switch activation digital control circuit 404. The example laser pulse duration digital control circuit 402 is configured to receive the illumination source enable signal 116 and generate a duration target code 406. The select switch activation digital control circuit 404 is configured to receive the duration target code 406, the main switch state signal 112, and the select switch state signal 114 from the laser pulse duration digital control circuit 402, and generate a main switch enable signal 118 and a select switch enable signal 120.

[0069] like Figure 4 As depicted in , the example switch control circuit 110 includes a laser pulse duration digital control circuit 402 (e.g., a first control circuit). The laser pulse duration digital control circuit 402 may be any hardware, firmware, software, or combination thereof configured to receive the illumination source enable signal 116 and output a duration object code 406 indicating a pulse width of a pulsed illumination output (e.g., the pulsed illumination output 126). The laser pulse duration digital control circuit may be combined with Figure 5Detailed description is given below. In some embodiments, a target pulse width may be indicated. The target pulse width may be indicated by an external user, may be determined based on calibration, may be determined based on the number of channels and oscillation frequency of the pulse transmission circuit 102, or may be determined by other similar means. In some embodiments, the target pulse width may be variable during operation and may be updated based on operating parameters of the system, the surrounding environment, and / or other factors. In some embodiments, the target pulse width may be fixed at startup based on input or configuration parameters.

[0070] The target pulse width (e.g., target duration) may be any data structure or variable configured to indicate the duration of the generated pulsed illumination output 126. In some applications, including LIDAR applications, the accuracy of the measurement may depend on the duration of the generated pulsed illumination output 126. For example, the measured distance and other information about the surrounding environment may be affected by changes and / or variations in the pulse width of the generated pulsed illumination output 126. The laser pulse duration digital control circuit 402 may receive the illumination source enable signal 116 and compare the pulse width of the illumination source (e.g., laser diode 310) to the target pulse width. The duration target code 406 may be updated based on the comparison.

[0071] like Figure 4 As further depicted in FIG. 4 , the laser pulse duration digital control circuit 402 may generate a duration target code 406. The duration target code 406 may be any data structure, number, sequence of numbers, or the like that indicates the duration of the pulse width of the pulsed illumination output 126. For example, in some embodiments, the duration target code 406 may represent a pulse duration (e.g., the duration of the illumination source enable signal 116) measured from the target duration (e.g., the duration of the illumination source enable signal 116). Figure 5 The correction code is derived from the difference between the target pulse width 518 described further below. If the two are equal, then no modification is required to the duration target code 406, otherwise the duration target code 406 is updated accordingly. In such an embodiment, time may be measured in seconds, nanoseconds, clock cycles, or any other similar measurement device.

[0072] like Figure 4 As further depicted in , the example switch control circuit 110 includes a select switch activation digital control circuit 404 (e.g., a second control circuit). The select switch activation digital control circuit 404 can be any hardware, firmware, software, or combination thereof configured to generate the main switch enable signal 118 and the select switch enable signal 120 so that synchronization of the main switch switching device (e.g., the main switch switching device 306) and the select switch switching device (e.g., the select switch switching device 308) is synchronized.

[0073] In order to ensure a continuous path for the oscillating current generated by the pulse emission circuit 102, a certain amount of overlap time must be ensured between the activation of the main switch switching device and each of the selective switch switching devices. In particular, the overlap at the end of the pulse must be minimized to increase the speed at which the lighting device is turned off. Increasing the speed at which the lighting device is turned off can improve the accuracy of measurements based on the generated pulsating lighting output. Therefore, the selective switch activation digital control circuit 404 can generate the main switch enable signal 118 and the one or more selective switch enable signals 120 so that the target overlap is obtained.

[0074] The target overlap may be any data structure or variable configured to indicate a time period for which the select switch device remains enabled once the main switch device is enabled. For example, in the case where the illumination source is enabled by the select switch device, the main switch device may be enabled for a period of time before the select switch device is disabled. Such a period of time is referred to as overlap. The target overlap is the desired amount of time that the main switch device may be enabled before the select switch device is disabled. The desired amount of time may be indicated in seconds, microseconds, nanoseconds, clock cycles, or any other similar measurement device. For example, the target overlap may be 1 nanosecond, or as another example, four clock cycles. The target overlap may be indicated by an external user, may be determined based on calibration, may be determined based on the number of channels and oscillation frequency of the pulse emission circuit 102, or may be determined by other similar means. In some embodiments, the target overlap may be variable during operation and may be updated based on operating parameters of the employing system, the surrounding environment, and / or other factors. In some embodiments, the target overlap may be fixed at startup based on input or configuration parameters.

[0075] Reference now Figure 5 , an example embodiment of the laser pulse duration digital control circuit 402 is provided. Figure 5 As depicted in , the laser pulse duration digital control circuit 402 includes a pulse duration operational amplifier 502 configured to receive the illumination source enable signal 116 and output an amplified illumination source enable signal 510. The depicted laser pulse duration digital control circuit 402 also includes a pulse width time to digital converter (TDC) 514 electrically connected to the pulse duration operational amplifier 502 and configured to receive the amplified illumination source enable signal 510 and a target pulse width 518 and determine an illumination signal offset 516. A pulse width proportional-integral-derivative (PID) is electrically connected to the pulse width TDC 514 and configured to receive the illumination signal offset 516 and generate a duration target code 406 based at least in part on the illumination signal offset 516. As shown in FIG. Figure 5As further depicted in FIG, the pulse width TDC 514 includes a pulse width programmable delay line 504 configured to receive a target pulse width 518 and compare the amplified illumination source enable signal 510 with the inverse of an illumination target off signal 512 generated by the pulse width programmable delay line 504 at a pulse width phase detector 506 to generate an illumination signal offset 516.

[0076] like Figure 5 As depicted in , the example laser pulse duration digital control circuit 402 includes a pulse duration operational amplifier 502. The pulse duration operational amplifier 502 may be any electronic component configured to receive an input voltage and generate an amplified output voltage proportional to the received input voltage. Figure 5 As shown in , the pulse duration operational amplifier 502 receives the illumination source enable signal 116 and generates an amplified illumination source enable signal 510. The amplified illumination source enable signal 510 is transmitted to the pulse width TDC 514 for further analysis as described herein. In some embodiments, the pulse duration operational amplifier 502 may include a comparator that may be configured to generate the amplified illumination source enable signal 510 based on the voltage level of the illumination source enable signal 116 signal (e.g., above a first threshold and below a second threshold).

[0077] like Figure 5 As further depicted in , the laser pulse duration digital control circuit 402 includes a pulse width TDC 514. The pulse width TDC 514 can be any hardware, firmware, software, or combination thereof configured to receive a signal having a defined pulse width and a target pulse width 518 and determine a difference between the target pulse width 518 and the defined pulse width. In some embodiments, the pulse width TDC 514 can include a process voltage and temperature (PVT) invariant component, such as a PVT invariant pulse width programmable delay line 504. The pulse width TDC 514 including the PVT invariant component can be robust to changes in temperature and process voltage when determining the duration target code 406. As shown in FIG. Figure 5 The TDC implementation depicted in represents one specific embodiment, however, any TDC implementation that relies on a PVT-invariant delay line may be used to generate the illumination signal offset 516 .

[0078] like Figure 5 As further depicted in FIG. 5 , the example pulse width TDC 514 includes a pulse width phase detector 506. The pulse width phase detector 506 may be any electronic device configured to measure the phase difference between two input signals and generate an output proportional to the phase difference between the two signals. Figure 5 As shown in , the first input of the pulse width phase detector 506 can be the amplified illumination source enable signal 510. The second input of the pulse width phase detector is the inversion of the illumination target off signal 512. In some embodiments, the amplified illumination source enable signal 510 is used in two polarities: one polarity is used to capture the laser on and then delayed to generate the illumination target off signal 512; one polarity is used to capture the laser off and is provided to the phase detector 506. The polarities of the amplified illumination source enable signal 510 and the illumination target off signal 512 at the input of the phase detector 506 can then be selected in such a way that the phase detector 506 can quantify the difference between the actual pulse duration (information included in the amplified illumination source enable signal 510) and the expected pulse duration (information included in the illumination target off signal 512). In such embodiments, the amplified illumination source enable signal 510 can be inverted at the pulse width phase detector 506, and the illumination target off signal 512 can be compared without inversion.

[0079] like Figure 5 As further depicted in FIG. 5 , the illumination target off signal 512 is generated by transmitting the amplified illumination source enable signal 510 via a pulse width programmable delay line 504 (e.g., a first programmable delay line). The pulse width programmable delay line 504 may be any hardware, firmware, software, or any combination thereof configured to receive a signal (e.g., the amplified illumination source enable signal 510) and a delay (e.g., a target pulse width 518) and delay the signal by the delay. Thus, the illumination target off signal 512 may include the amplified illumination source enable signal 510 delayed by the target pulse width 518. Thus, when the amplified illumination source enable signal 510 is de-asserted, the illumination target off signal 512 may be asserted. By inverting the illumination target off signal 512 at the pulse width phase detector 506, the difference between the pulse width of the amplified illumination source enable signal 510 and the target pulse width 518 may be measured. The illumination signal offset 516 may represent the difference between the pulse width of the amplified illumination source enable signal 510 and the target pulse width 518.

[0080] like Figure 5 As further depicted in FIG. 4 , the example laser pulse duration digital control circuit 402 includes a pulse width PID 508. The pulse width PID 508 may be any device configured to generate a signal based on an error between an expected signal and an actual measured value, including hardware, firmware, software, or any combination thereof. Figure 5As shown in , the pulse width PID 508 may generate the duration target code 406 based on an illumination signal offset 516 that represents a difference between a pulse width duration of the illumination source enable signal 116 and a target pulse width 518 .

[0081] Reference now Figure 6 , an example selector switch activation digital control circuit 404 is provided. Figure 6 As shown in FIG. 1 , the example select switch activation digital control circuit 404 receives the duration target code 406 from the laser pulse duration digital control circuit 402 and generates two input signals: a select switch OFF signal 630 and a select switch ON signal 632, wherein the select switch ON signal 632 corresponds to the select switch enable signal 120, and the select switch OFF signal 630 is determined based on applying a delay based on the duration target code 406 to the select switch ON signal 632. Two intermediate signals are generated from the select switch OFF signal 630: a select switch OFF configurable delay signal 636 and a select switch OFF fixed delay signal 638. In addition, a select switch ON fixed delay signal 640 is generated from the select switch ON signal 632.

[0082] like Figure 6 , the select switch closure fixed delay signal 638 is generated by transmitting the select switch closure signal 630 via the fixed delay line 604, which is configured to add a delay to the select switch closure configurable delay signal 636 and the select switch closure fixed delay signal 638 to enable adjustment when necessary. For example, the fixed delay line 604 can be inserted to compensate for the maximum difference between the propagation delay of the main switch driver (e.g., the delay between the assertion of the main switch enable signal 118 and the actual opening of the main switch switching device) and the propagation delay of the select switch driver (e.g., the delay between the de-assertion of the select switch enable signal 120 and the actual closing of the select switch switching device 308). In other words, the fixed delay line 604 enables the select switch activation digital control circuit 404 to adjust the value in the select switch closure programmable delay line 602 to generate the select switch closure configurable delay signal 636, which can anticipate the select switch closure fixed delay signal 638 when necessary. Thus, in situations where the pulsed lighting generator circuit experiences large propagation delays on the electrical path to the select switch circuitry 106 , the select switch activation digital control circuit 404 can predict the select switch closure configurable delay signal 636 relative to the select switch closure fixed delay signal 638 .

[0083] The select switch off configurable delay signal 636 is similarly generated by transmitting the select switch off signal 630 through the select switch off programmable delay line 602. In the case where the propagation delay for the select switch driver is equal to the propagation delay for the main switch driver, the select switch activation digital control circuit 404 can program the select switch off programmable delay line 602 to be equal to the fixed delay line 604. Only the target overlap 652, which is programmed into the select switch overlap programmable delay line 624, is actually delayed. In the case where the propagation delay for the select switch driver is not equal to the propagation delay for the main switch driver, the programmed propagation delays in the select switch off programmable delay line 602 and the fixed delay line 604 will not be equal. Therefore, the select switch activation digital control circuit 404 can increase or decrease the programmed delay of the select switch off programmable delay line 602 to compensate for this mismatch.

[0084] By utilizing the select switch close signal 630 , the fixed internal delay, and the overlay target code 650 to generate the select switch close configurable delay signal 636 , the select switch close configurable delay signal 636 may indicate the precise time at which the select switch enable command 644 may be de-asserted.

[0085] like Figure 6 As further depicted in FIG. 6 , the select switch on fixed delay signal 640 is generated by transmitting the select switch on signal 632 via the select switch on fixed delay line 606, corresponding to an internal delay associated with the time between the arrival of the change in the enable signal and the signal transition due to the activation of the switch mechanism. In some embodiments, the programmed delay of the select switch on fixed delay line 606 can be equal to the programmed delay of the fixed delay line 604.

[0086] like Figure 6 As further depicted in , in instances where there are multiple channels and each channel has a select switch enable signal, a select switch select multiplexer 608 may be utilized to generate a select multiplexer enable signal 634 that indicates assertion of any select switch enable signal from the multiple channels.

[0087] like Figure 6As further depicted in FIG. 4 , the select switch activation digital control circuit 404 includes a select switch phase generation module 612 configured to receive at least a select switch closure configurable delay signal 636, a select switch closure fixed delay signal 638, a select switch closure fixed delay signal 640, and a select multiplexer enable signal 634. The select switch phase generation module 612 is further configured to generate a select switch enable command 644 and a main switch enable command 642a. The select switch phase generation module 612 can be any hardware, software, firmware, or combination thereof configured to receive one or more input signals and generate a plurality of output signals based on the phases of the one or more input signals. Figure 6 , the input signals of the selection switch phase generation module 612 may include at least a selection switch closure configurable delay signal 636, a selection switch closure fixed delay signal 638, and a selection switch on fixed delay signal 640. In some embodiments, the assertion of the selection switch enable command 644 may be determined based on the assertion of the selection multiplexer on signal 634, and the de-assertion of the selection switch enable command 644 may be determined based on the assertion of the selection switch closure configurable delay signal 636. Additionally, in some embodiments, the de-assertion of the main switch enable command 642a may correspond to the selection switch on fixed delay signal 640, and the assertion of the main switch enable command 642a prior to the de-assertion of the selection switch enable command 644 may correspond to the selection switch closure fixed delay signal 638.

[0088] like Figure 6 As further depicted in FIG. 1 , the select switch enable command 644 is transmitted to the select switch enable driver 618, which amplifies the select switch enable command 644 for transmission as the select switch enable signal 120 to the select switch device (e.g., the select switch device 308) for the particular channel. Figure 6 As further depicted in FIG. 1 , the master switch enable command 642a is transmitted to an OR logic gate 614. In some embodiments, in a multi-channel application, an OR logic gate 614 may be included to receive the master switch enable commands 642a-642d for each channel. Thus, a combined master switch enable command 615 is generated based on a logical combination of each master switch enable command 642a-642d from each channel. The combined master switch enable command 615 is transmitted to a master switch enable driver 616, which amplifies the combined master switch enable command 615 and transmits it to a master switch switching device (e.g., the master switch switching device 306) as a main switch enable signal 118.

[0089] like Figure 6As further depicted in FIG. 1 , the main switch state signal 112 and the select switch state signal 114 are used to generate an overlapping target code 650 for the next resonant cycle. Figure 6 As depicted in , the example select switch activation digital control circuit 404 also includes a select switch overlap TDC 660 (e.g., a second time to digital converter). The select switch overlap TDC 660 can be any hardware, firmware, software, or combination thereof configured to receive two input signals, determine the difference between events in the signals, and output one or more signals representing the difference. In some embodiments, the select switch overlap TDC 660 can include process voltage and temperature (PVT) invariant components, such as a PVT invariant select switch overlap programmable delay line 624. The select switch overlap TDC 660 including the PVT invariant components can be robust to changes in temperature and process voltage when determining the select signal overlap offset 662 to the select switch overlap PID 628.

[0090] like Figure 6 As depicted in , the select switch overlap TDC 660 is configured to generate an output (e.g., select signal overlap offset 662) that represents the difference between the offset between the turn-on of the main switch state signal 112 and the corresponding turn-off of the select switch state signal 114 and the target overlap. In some embodiments, the inverse of the select switch state signal 114 and the main switch state signal 112 may be transmitted to the first and second inputs of the select switch overlap TDC 660. Figure 6 As shown in , in some embodiments, the state of the selection switch switching device and the main switch switching device can be determined by a comparator (e.g., the selection switch enable comparator 620, the main switch enable comparator 622), which is configured to compare the gate voltage of the switching device with the source voltage and determine whether the switching device is enabled or disabled.

[0091] like Figure 6As further depicted in FIG. 6 , the select switch overlap TDC 660 includes a select switch overlap phase detector 626 configured to receive a select switch enable inverted signal 646 and a main switch enable delayed signal 648. The select switch enable inverted signal 646 can be transmitted directly from the input of the select switch overlap TDC 660 to the select switch overlap phase detector 626. However, the main switch enable signal 118 is transmitted through a select switch overlap programmable delay line 624 (e.g., a second programmable delay line) configured to delay the main switch state signal 112 by a target overlap 652. As described herein, the target overlap 652 can be a desired amount of time that the main switch switching device is enabled before the select switch switching device is disabled. By comparing the main switch state signal 112 delayed by the target overlap 652 with the inverted phase of the select switch state signal 114, the select switch overlap phase detector 626 can determine the offset of the disablement of the select switch switching device from the target overlap 652.

[0092] like Figure 6 As further depicted in FIG. 6 , the select signal overlap offset 662 output by the select switch overlap TDC 660 is transmitted to the select switch overlap PID 628. The select switch overlap PID 628 may be any device configured to generate a signal based on the error between the expected signal and the actual measured value, including hardware, firmware, software, or any combination thereof. Figure 6 As shown in , the select switch overlap PID 628 can generate an overlap target code 650 based on a select signal overlap offset 662 that represents the difference between the select switch enable inverted signal 646 and the main switch enable delayed signal 648 delayed by a target overlap 652 .

[0093] like Figure 6 As further depicted in , the overlap target code 650 generated based on the offset of the select switch state signal 114 and the main switch state signal 112 from the target overlap 652 can be used to update the delay of the select switch closing programmable delay line 602, thereby adjusting the overlap of the select switch and the main switch.

[0094] Reference now Figure 7 , an example pulsating lighting generator circuit 700 including four channels is provided. Figure 7 As depicted in FIG. 7 , the example pulsed illumination generator circuit 700 includes a pulse emission circuit 102. The pulse emission circuit 102 is electrically connected to an input of a pulse signal generator 124, which is then electrically connected to the illumination source circuit system 108, then returned to the pulse emission circuit 102, and directly electrically connected back to the pulse emission circuit 102 at another output. Figure 7As depicted in , the pulse signal generator 124 also includes a main switch circuit system 104 and a selection switch circuit system 106 connected in parallel, and the input end of each switch circuit system is electrically connected to the pulse emission circuit 102. The output end of the main switch circuit system 104 is electrically connected back to the pulse emission circuit 102, and the output end of the selection switch circuit system 106 is electrically connected in series to the input end of the illumination source circuit system 108, and the output end of the illumination source circuit system 108 is then electrically connected to the pulse emission circuit 102. Figure 7 As further depicted in , the pulse signal generator 124 includes a switch control circuit 110 electrically connected to send and receive electronic data from the main switch circuit system 104, the selection switch circuit system 106 and the illumination source circuit system 108.

[0095] like Figure 7 As depicted in FIG. 1 , the example pulsed illumination generator circuit 700 includes four channels, including four laser diodes 702a-702d and four switch devices 704a-704d. Each of the four switch devices 704a-704d is configured to receive a selection switch enable signal 706a-706d from the switch control circuit 110. In addition, each of the laser diodes 702a-702d is configured to generate an illumination source enable signal 708a-708d. However, since there is only one main switch device 710, only a single and Figure 1-Figure 6 The main switch enable signal 712 described in the related description. In order to generate such a signal, a laser pulse duration digital control circuit (such as the one described in the related description) can be implemented for each of the transmission channels (CH1, CH2, CH3, CH4). Figure 4-Figure 5 described) and the selector switch activates the digital control circuit (as described with respect to Figure 5 , Figure 6 The switch control circuit 110 supporting multiple channels may generate a selection switch enable command (e.g., the selection switch enable command 644) and a combined main switch enable command (e.g., the main switch enable command 615) for each channel to instruct the behavior of the main switch device 710 according to all channels. Figure 7 Although depicted as four channels, the pulsed illumination generator circuit 700 can support one or more transmission channels.

[0096] Reference now Figure 8 , an example signal diagram 800 of an example four-channel pulsating signal generator (e.g., pulsating signal generator 724) is provided. Figure 8As depicted in FIG. 8 , in a four-channel pulse signal generator, current (802, 806, 810, 814, 818) is switched sequentially between the main switch and each transmission channel. For example, current flows through the main switch, as indicated by the main switch current 802, then flows through the select switch 1, as indicated by the select switch 1 current 806, then returns to the main switch, then flows through the select switch 2, as indicated by the select switch 2 current 810, then returns to the main switch, then flows through the select switch 3, as indicated by the select switch 3 current 814, then returns to the main switch, then flows through the select switch 4, as indicated by the select switch 4 current 818, and then finally returns to the main switch. Alternating current between the main switch and each of the four transmission channels enables control of the duration of each pulsed illumination output and enables control of the speed at which the laser diode turns on and off. Main switch VGS 804, select switch 1 VGS 808, select switch 2 VGS 812, select switch 3 VGS 816, and select switch 4 VGS 820 depict the corresponding gate-source voltages of the select switch switching devices at each circuit, corresponding to the select switch enable signal (e.g., select switch enable signals 120, 706a-706d) for each transmission channel.

[0097] like Figure 8 As further depicted in FIG. 1 , target pulse width 1, target pulse width 2, target pulse width 3, and target pulse width 4 correspond to the pulse width of the pulsed illumination output of each channel, corresponding to the select switch enable signal (e.g., illumination source enable signal 116, 708a-708d) and the duration target code. Additionally, labels overlap 1, overlap 2, overlap 3, and overlap 4 indicate the overlap between the enablement of the main switch switching device and the disablement of the select switch switching device.

[0098] Reference now Fig. 9 , a flow chart depicting an example process 900 for generating a pulsed lighting signal (e.g., the pulsed lighting signal 122) according to one or more embodiments of the present disclosure is provided. At block 902, a pulsed signal generator (e.g., the pulsed signal generator 124, the pulsed signal generator 724) receives a pulsed electronic signal. As described herein, the pulsed electronic signal may be generated by a pulse transmission circuit (e.g., the pulse transmission circuit 102). The pulse transmission circuit may generate the pulsed electronic signal at a specific resonant frequency. In some embodiments, the pulsed signal generator may be configured to enable multiple transmission channels during a single resonant cycle of the pulsed electronic signal.

[0099] At block 904, the pulsating signal generator receives an illumination source enable signal (e.g., illumination source enable signal 116, 708a-708d) from the illumination source indicating a state of the illumination source. As described herein, in some embodiments, the illumination source enable signal may be generated based at least in part on a voltage at an anode of a laser diode or other illumination source. The illumination source enable signal may indicate whether the illumination source is on or off.

[0100] At block 906, the pulsating signal generator generates a duration target code (e.g., duration target code 406) at the first control circuit based at least in part on the lighting enable signal, the duration target code indicating a comparison between the duration of the lighting enable signal and a target duration of the lighting enable signal. As described herein, in some embodiments, the pulsating signal generator may include a first control circuit configured to determine the duration target code based on a desired target duration. The desired target duration may indicate a desired pulse width of the pulsating lighting output, and the duration target code indicates an adjustment to the select switch enable signal necessary to obtain the desired target duration.

[0101] In some embodiments, the pulsating signal generator may also generate a lighting target off signal (e.g., lighting target off signal 512) by delaying the lighting source enable signal by the target duration at a first time-to-digital converter (TDC) (e.g., pulse width TDC 514) of the first control circuit. Additionally, the pulsating signal generator may determine a lighting signal offset (e.g., lighting signal offset 516) between the lighting source enable signal and the inverse phase of the lighting target off signal at a first phase detector (e.g., pulse width phase detector 506) of the first control circuit. Additionally, the pulsating signal generator may receive the lighting signal offset at a first proportional-integral-derivative controller (e.g., pulse width PID 508) and generate a duration target code based on the lighting signal offset.

[0102] At block 908, the ripple signal generator receives the duration target code at a second control circuit (e.g., the selector switch activation digital control circuit 404). In some embodiments, the second control circuit is designed as a cascade of the first control circuit. Therefore, a change in the duration target code does not affect the overlap target code, and vice versa.

[0103] At block 910, the pulsating signal generator determines at the second control circuit a main switch enable signal (e.g., main switch enable signal 118) configured to activate a main switch (e.g., main switch switching device 306, main switch device 710). In some embodiments, the main switch enable signal can activate and deactivate the main switch switching device in the pulsating signal generator, thereby allowing current to flow through the main switch circuit system. The main switch enable signal can be synchronized with a select switch enable signal (e.g., select switch enable signal 120) to control the on and off speed of the pulsed lighting output.

[0104] At block 912, the pulsating signal generator determines a select switch enable signal at the second control circuit based at least in part on the duration target code and the target overlap with the main switch enable signal, wherein the select switch enable signal is configured to activate the select switch (e.g., the select switch switch device 308, the select switch switch device 704a-704d), and wherein the select switch enables current to flow to the illumination source (e.g., the laser diode 310, 702a-702d). As described herein, the select switch enable signal can be synchronized with the main switch enable signal to control the pulsating illumination output. For example, the brief overlap in time that the main switch and the select switch are enabled can increase the speed at which the illumination source is turned off, thereby enabling improved measurement of the received reflection.

[0105] In some embodiments, blocks 910 and 912 may further include receiving a select switch state signal (e.g., select switch state signal 114) and a main switch state signal at a second time-to-digital converter (e.g., select switch overlap TDC 660) of a second control circuit, wherein the select switch state signal is based at least in part on the select switch enable signal (e.g., select switch enable signal 120), and wherein the main switch state signal (e.g., main switch state signal 112) is based at least in part on the main switch enable signal (e.g., main switch enable signal 118), and determining the select signal offset based at least in part on a time difference between the target overlap and an overlap of the select switch state signal and the main switch state signal.

[0106] Additionally, the ripple signal generator may receive a select signal offset at a second proportional-integral-derivative controller (e.g., select switch overlap PID 628) of a second control circuit and generate an overlap target code (e.g., overlap target code 650) based at least in part on the select signal offset.

[0107] In some embodiments, the pulsation signal generator can receive the overlap target code and the target overlap at the illumination signal off programmable delay line (e.g., the selection switch off programmable delay line 602) of the second control circuit, and generate an illumination off signal (e.g., the selection switch off configurable delay signal 636) based at least in part on the overlap target code and the target overlap.

[0108] Reference now Fig.10 , an example LIDAR system 1000 is provided. Fig.10 As shown in , the example LIDAR system 1000 includes a controller 1002 configured to control a pulse transmission circuit 102 electrically connected to a pulse signal generator 124, and an illumination source circuit system 108 configured to generate a pulsed illumination output 126 upon receiving a pulsed illumination signal 122 from a switch control circuit (e.g., switch control circuit 110). The controller 1002 is also configured to receive reflected pulsed illumination 1006 via a transmit pulse receiver 1004.

[0109] like Fig.10 As depicted in , the example LIDAR system 1000 includes a controller 1002. In an example embodiment, the controller 1002 is configured to execute instructions stored in a data storage medium or otherwise accessible to the controller 1002. Alternatively or additionally, in some embodiments, the controller 1002 is configured to execute hard-coded functionality. Therefore, whether configured by hardware or software methods, or by a combination of both, the controller 1002 represents an entity (e.g., physically implemented in a circuit system) that is capable of performing operations in accordance with embodiments of the present disclosure when configured accordingly. Alternatively or additionally, as another example in some example embodiments, when the controller 1002 is implemented as an executor of software instructions, the instructions specifically configure the controller 1002 to perform algorithms implemented in specific operations described herein when executing such instructions.

[0110] For example, in some embodiments, the controller 1002 may be configured to perform various operations associated with configuring the pulse transmission circuit 102 and the pulsation signal generator 124. The operations may include, but are not limited to, configuring the resonance period of the pulse transmission circuit 102, configuring the target pulse width and target overlap in the pulsation signal generator 124, and the like.

[0111] like Fig.10As depicted in , the illumination source circuitry 108 can be configured to control the pulsed illumination output 126 from one or more laser diodes (e.g., laser diode 310, laser diodes 702a-702d). As described herein, the pulsed illumination output 126 of the one or more laser diodes can be determined by a switch control circuit (e.g., switch control circuit 110) configured to generate one or more illumination source enable signals (e.g., illumination source enable signal 116, illumination source enable signal 510, illumination source enable signals 708a-708d) and one or more selection switch enable signals (e.g., selection switch enable signal 120, selection switch enable signals 706a-706d).

[0112] Additionally, the controller 1002 may be configured to receive an electrical signal based on the reflected pulsed illumination 1006 received by the transmit pulse receiver 1004 and perform signal processing operations to determine certain characteristics of the received signal. The controller 1002 may further determine a time-of-flight measurement based on a comparison of the reflected pulsed illumination 1006 to the pulsed illumination output 126. The time-of-flight measurement may enable the controller 1002 to determine the distance of an object in the surrounding environment.

[0113] like Fig.10 As further depicted in FIG. 1 , the example LIDAR system 1000 may include a transmit pulse receiver 1004 configured to receive reflected pulsed illumination 1006 and transmit a corresponding electrical signal to the controller 1002. The transmit pulse receiver 1004 may be any electronic sensor or device configured to detect reflected light and convert the light into electrical energy. In some embodiments, the transmit pulse receiver 1004 may include a photodiode, an avalanche photodiode, a silicon photomultiplier tube, a PIN photodiode, or other similar detector.

[0114] Although this detailed description has set forth some embodiments of the invention, the appended claims cover other embodiments of the invention that differ from the described embodiments according to various modifications and improvements. For example, those skilled in the art will recognize that such principles can be applied to any electronic device that employs pulsating electronic signals that require high precision. For example, various LIDAR systems, time-of-flight cameras, ultrasonic distance sensors, and other similar devices.

[0115] In the following claims, unless the specific terms "means for" or "step for" are used in a given claim, it is not intended that the claim be interpreted under 35 USC 112, paragraph 6.

[0116] The use of broader terms such as "comprising," "including," and "having" should be understood to support narrower terms such as "consisting of," "consisting essentially of," and "consisting substantially of." The use of the terms "optional," "may," "perhaps," "might," and the like with respect to any element of an embodiment means that the element is not required, or, alternatively, the element is required, both options are within the scope of the embodiment(s). Moreover, references to examples are provided for illustrative purposes only and are not intended to be exclusive.

Claims

1. An electronic system comprising: a pulse transmitting circuit electrically connected to the illumination source; as well as Pulse signal generator, including: a main switch electrically connected to the pulse transmitting circuit; Selector switch, electrically connected to the main switch, wherein the selector switch controls the flow of current to the lighting source; and A switch control circuit, comprising: The first control circuit, wherein the first control circuit receives an illumination source enable signal indicating a state of the illumination source, and wherein the first control circuit generates a duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration of the illumination source enable signal; and The second control circuit, wherein the second control circuit receives the duration target code, and Wherein the second control circuit determines a main switch enable signal configured to activate the main switch and a select switch enable signal configured to activate the select switch based at least in part on the duration target code and the target overlap.

2. The electronic system as claimed in claim 1, wherein the first control circuit of the switch control circuit further comprises a first time-to-digital converter TDC, The first TDC is configured to determine an illumination signal offset between a duration of the illumination source enable signal and a target duration of the illumination source enable signal.

3. The electronic system of claim 2, wherein the first control circuit further comprises a first proportional-integral-derivative controller configured to generate a duration target code based on the illumination signal offset.

4. The electronic system of claim 1 , wherein the second control circuit further comprises a second time-to-digital converter (TDC) configured to determine the selection signal offset, The selection signal offset represents the time difference between the target overlap and the overlap of the selection switch state signal and the main switch state signal. wherein the select switch state signal is based at least in part on the select switch enable signal, and The main switch state signal is at least partially based on the main switch enable signal.

5. The electronic system of claim 4, wherein the second control circuit further comprises a second proportional-integral-derivative controller configured to generate the overlapping target code based on the selection signal offset. 6 . The electronic system of claim 5 , wherein the second control circuit further comprises an illumination signal off programmable delay line configured to generate the illumination off signal based on the overlap target code and the target overlap. 7 . The electronic system of claim 6 , wherein the second control circuit de-asserts the selection switch enable signal based on the lighting off signal.

8. The electronic system of claim 1, further comprising a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch.

9. The electronic system of claim 5, wherein the second control circuit is a cascade of the first control circuit so that adjustments to the duration target code do not affect the overlap target code, and adjustments to the overlap target code do not affect the duration target code.

10. A method for generating a pulsating lighting signal, the method comprising: receiving a pulsating electronic signal at a pulsating signal generator; receiving, at the pulsating signal generator, a lighting source enable signal from the lighting source indicating a state of the lighting source; generating, at the first control circuit, a duration target code based at least in part on the illumination source enable signal, the duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration for the illumination source enable signal; receiving a duration target code at a second control circuit; determining, at the second control circuit, a main switch enable signal configured to activate the main switch; determining, at the second control circuit, a select switch enable signal based at least in part on the duration target code and a target overlap with the main switch enable signal, wherein the select switch enable signal is configured to activate the select switch, and wherein the switch is selected to enable current to flow to the illumination source; and A pulsed illumination signal is generated based at least in part on the select switch enable signal.

11. The method of claim 10, further comprising: An illumination signal offset between a duration of the illumination source enable signal and a target duration of the illumination source enable signal is determined at a first time-to-digital converter TDC of the first control circuit.

12. The method of claim 11, further comprising: receiving a lighting signal offset at a first proportional-integral-derivative controller; as well as A duration target code is generated based on the illumination signal offset.

13. The method of claim 10, further comprising: receiving the select switch state signal and the main switch state signal at a second time-to-digital converter of a second control circuit, wherein the select switch state signal is based at least in part on the select switch enable signal, and wherein the main switch state signal is based at least in part on the main switch enable signal; and The select signal offset is determined based at least in part on a time difference between the target overlap and the overlap of the select switch state signal and the main switch state signal.

14. The method of claim 13, further comprising: receiving a select signal offset at a second proportional-integral-derivative controller of a second control circuit; as well as An overlapping target code is generated based at least in part on the selection signal offset.

15. The method of claim 14, further comprising: receiving an overlap target code and a target overlap at an illumination signal deactivation programmable delay line of a second control circuit; as well as An illumination shutoff signal is generated based at least in part on the overlapping target code and the target overlap.

16. The method of claim 15, further comprising: The select switch enable signal is de-asserted based at least in part on the lighting off signal.

17. The method of claim 10, wherein the pulsating signal generator further comprises a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch.

18. The method of claim 14, wherein the second control circuit is a cascade of the first control circuit so that adjustments to the duration target code do not affect the overlap target code, and adjustments to the overlap target code do not affect the duration target code.

19. A light detection and ranging LIDAR system comprising: Controller; a pulse emission circuit and an illumination source electrically connected to the controller, wherein the illumination source is configured to generate a light output based at least in part on the illumination source enable signal; Pulse signal generator, including: a main switch electrically connected to the pulse transmitting circuit; Selector switch, electrically connected to the main switch, wherein the selector switch controls the flow of current to the lighting source; and A switch control circuit, comprising: The first control circuit, wherein the first control circuit receives an illumination source enable signal indicating a state of the illumination source, and wherein the first control circuit generates a duration target code indicating a comparison between a duration of the illumination source enable signal and a target duration of the illumination source enable signal; and The second control circuit, wherein the second control circuit receives the duration target code, and wherein the second control circuit determines a main switch enable signal configured to activate the main switch and a select switch enable signal configured to activate the select switch based at least in part on the duration target code and the target overlap; and a transmit pulse receiver electrically connected to the controller and configured to receive a reflection of the light output from the object; Wherein the controller is configured to determine a distance of the object based on reflection of the light output.

20. The light detection and ranging (LIDAR) system of claim 19, wherein the pulse signal generator further comprises a plurality of selection switches and a plurality of switch control circuits, each switch control circuit being associated with one selection switch.

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