KR-102964240-B1 - ELECTRONIC DEVICE MONITORING DISCHARGE STATE OF PHOTO DIODE AND METHOD OF CONTROLLING FOR THE SAME

Abstract

The electronic device includes: a photodiode in which the anode is connected to an internal node to which a negative voltage is applied and the cathode is connected to an output terminal; a transistor in which one end is connected to the internal node; a discharge control circuit that controls the discharge of a negative charge from the internal node to the other end of the transistor based on a discharge control signal in a power-off sequence; and a discharge monitoring circuit that includes a discharge resistor connected to the other end of the transistor and detects the voltage to the other end of the transistor to output a feedback signal regarding whether the power-off sequence is completed.

Inventors

• 김남형
• 이승용

Assignees

• 현대모비스 주식회사

Dates

Publication Date

20260512

Application Date

20220914

Claims (20)

1. A photodiode in which the anode is connected to an internal node to which a negative voltage is applied, and the cathode is connected to an output terminal; A transistor connected to the above internal node; A discharge control circuit that controls the negative charge of the internal node to be discharged to the other end of the transistor based on a discharge control signal in a power-off sequence; and An electronic device comprising a discharge monitoring circuit that includes a discharge resistor connected to the other end of the transistor and detects a voltage to the other end of the transistor to output a feedback signal regarding whether the power-off sequence is completed.
2. In Article 1, The above photodiode is, An electronic device implemented with a SPAD (Single-Photon Avalanche Diode).
3. In Article 2, The potential difference between the anode and the cathode is, An electronic device that is set higher than the breakdown voltage for the photodiode so that avalanche multiplication occurs with single photon reception during the power-on period.
4. In Article 1, The above discharge monitoring circuit is, An electronic device that converts the voltage to the other end of the transistor into a positive voltage to generate a monitoring voltage, and determines whether to activate the feedback signal according to the monitoring voltage.
5. In Paragraph 4, The above discharge monitoring circuit is, An electronic device further comprising an inverting amplifier that inverts and amplifies the voltage for the other end of the transistor to output the monitoring voltage.
6. In Article 5, The above inversion amplifier is, An electronic device that receives the above negative voltage through a negative power terminal.
7. In Paragraph 4, The above discharge monitoring circuit is, An electronic device further comprising a Schmitt trigger circuit that activates a feedback signal indicating that the power-off sequence is completed when the monitoring voltage is lower than a threshold voltage to which hysteresis is applied.
8. In Article 1, The above emission resistance is, An electronic device connected between the other end and the ground end of the above transistor.
9. In Article 1, The above transistor is, It is implemented with an NMOS transistor, but, One end of the above transistor corresponds to the source terminal, and An electronic device in which the other end of the above transistor corresponds to the drain end.
10. In Article 1, The voltage for the other end of the above transistor is, An electronic device that increases in the positive (+) direction as the above power-off sequence progresses.
11. In Article 1, The operating region of the above transistor is, An electronic device that transitions from a saturation region to a linear region as the power-off sequence proceeds.
12. In Article 1, The above discharge control signal is, An electronic device having a level greater than the threshold voltage of the transistor when the power-off sequence for the above photodiode proceeds.
13. In Article 1, The above discharge control circuit is, An electronic device that receives the above negative voltage as a negative power supply voltage through a negative power supply terminal, generates a driving voltage by adding the above negative voltage to the voltage of a discharge control signal based on the above negative power supply voltage, and controls the negative charge of the internal node to be discharged to the other end of the transistor by applying the above driving voltage to the gate terminal of the transistor.
14. A step of controlling, based on a discharge control signal in a power-off sequence, for the negative charge of an internal node connected to the anode of a photodiode and one end of a transistor to be discharged through a discharge resistor connected to the other end of the transistor; and A method for controlling an electronic device, comprising the step of detecting a voltage at the other end of the transistor and outputting a feedback signal regarding whether the power-off sequence is completed.
15. In Article 14, The step of outputting the above feedback signal is, A step of converting the voltage for the other end of the transistor into a positive voltage to generate a monitoring voltage; and A method for controlling an electronic device, comprising the step of determining whether to activate the feedback signal according to the monitoring voltage.
16. In Article 15, The step of generating the above monitoring voltage is, A method for controlling an electronic device, comprising the step of inverting and amplifying the voltage to the other end of the transistor through an inverting amplifier to output the monitoring voltage.
17. In Article 15, The step of determining whether the above feedback signal is activated is: A step of determining whether the monitoring voltage is lower than a hysteresis-applied threshold voltage through a Schmitt trigger circuit; and A method for controlling an electronic device, comprising the step of activating a feedback signal indicating that the power-off sequence is completed when the monitoring voltage is lower than the threshold voltage.
18. In Article 14, The above emission resistance is, A method for controlling an electronic device connected between the other end and the ground end of the above transistor.
19. In Article 14, The above transistor is, It is implemented with an NMOS transistor, but, One end of the above transistor corresponds to the source terminal, and A method for controlling an electronic device, wherein the other end of the above transistor corresponds to the drain end.
20. In Article 14, The above discharge control signal is, A method for controlling an electronic device having a level greater than the threshold voltage of the transistor when the power-off sequence for the above photodiode is performed.

Description

Electronic device monitoring the discharge state of a photodiode and method of controlling the same The present invention relates to an electronic device for monitoring the discharge state of a photodiode in a power-off sequence and a method for controlling the same. Light Detection and Ranging (LiDAR) systems are applied in various fields such as aerospace, geology, 3D mapping, automobiles, robots, and drones, and recently, Time of Flight (ToF) methods using Single-Photon Avalanche Diodes (SPADs) are being developed. A SPAD operates by applying a reverse bias, in which a negative voltage and a positive voltage are applied to the anode and cathode, respectively, just like a general photodiode (PD). At this time, the reverse bias can be applied from a negative voltage generating circuit that provides a voltage greater than the breakdown voltage of the SPAD. Since SPADs have a high breakdown voltage, they can have a high charge during the power-on period. Accordingly, the LiDAR system may be equipped with a discharge circuit that rapidly discharges the SPAD to mitigate damage to the SPAD during the power-off sequence. The discharge circuit may enter the operation of discharging the SPAD as the power-off sequence proceeds, but if the sequence following the power-off sequence proceeds before the operation of discharging the SPAD is completed, damage to the SPAD may occur. The matters described above as background technology are intended only to enhance understanding of the background of the present invention and should not be construed as an acknowledgment that they constitute prior art already known to those skilled in the art. FIG. 1 is a block diagram showing the configuration of an electronic device according to an example of the present invention. Figure 2 is a circuit diagram according to an example of a discharge monitoring circuit illustrated in Figure 1. Figure 3 is a graph illustrating the drain current change of the transistor shown in Figure 1. FIG. 4 is a flowchart for explaining a method of controlling an electronic device according to an example of the present invention. Hereinafter, embodiments disclosed in this specification will be described in detail with reference to the attached drawings. Identical or similar components regardless of drawing symbols are given the same reference number, and redundant descriptions thereof will be omitted. In describing the embodiments disclosed in this specification, if it is determined that a detailed description of related prior art may obscure the essence of the embodiments disclosed in this specification, such detailed description is omitted. Furthermore, the attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that they include all modifications, equivalents, and substitutions that fall within the spirit and technical scope of the present invention. Terms such as "first" and "second," used to distinguish various components, are not limited by the components. For example, the first component may be named the second component, and conversely, the second component may be named the first component. When it is stated that one component is "connected" or "connected" to another component, it should be understood that they are connected directly or through an intermediate component. On the other hand, the descriptions "directly connected" and "directly connected" should be understood as meaning that one component is directly connected to another component without any intermediary component. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. FIG. 1 is a block diagram showing the configuration of an electronic device according to an example of the present invention. As illustrated in FIG. 1, the electronic device may include a photodiode (10), a current source (20), a transistor (30), a discharge control circuit (40), and a discharge monitoring circuit (100). The electronic device according to the present embodiment may be applied to a LiDAR system, but is not necessarily limited thereto. The photodiode (10) can have its anode connected to an internal node (nd_INT) to which a negative voltage (Vn) is applied, and its cathode connected to an output terminal (OUT). In this case, the photodiode (10) can be implemented as a single-photon avalanche diode (SPAD). Accordingly, the potential difference between the anode and the cathode can be set higher