Search

US-12618948-B2 - Photodetection device

US12618948B2US 12618948 B2US12618948 B2US 12618948B2US-12618948-B2

Abstract

A first terminal is connected to a first electrode of an APD. First and second circuit units and are connected in parallel with each other to a second electrode of the APD. A second terminal is connected to the second electrode via the first circuit unit. A third terminal is connected to the second electrode via the second circuit unit. A first switch, a resistor, the second electrode, and the second terminal are connected in series with each other. A second switch and a capacitor are connected in parallel with each other to the second electrode. The second switch, the second electrode, and a third terminal are connected in series with each other. A TIA is connected in series with the capacitor and is connected to the second electrode via the capacitor.

Inventors

  • Masanori Muramatsu

Assignees

  • HAMAMATSU PHOTONICS K.K.

Dates

Publication Date
20260505
Application Date
20210714
Priority Date
20200722

Claims (13)

  1. 1 . A photodetection device comprising a plurality of photodetection units each having a light reception region, wherein: each of the photodetection unit includes: an avalanche photodiode including first and second electrodes and forming the light reception region; a first terminal connected to the first electrode and to which a first potential is applied; first and second circuit units connected in parallel with each other to the second electrode; a second terminal connected to the second electrode via the first circuit unit and to which a second potential is applied; and a third terminal connected to the second electrode via the second circuit unit and to which a third potential is applied, and in each of the photodetection units: the first circuit unit includes a resistor and a first switch for switching a connection state between the second electrode and the second terminal; the first switch, the resistor, the second electrode, and the second terminal are connected in series with each other; the second circuit unit includes a second switch for switching a connection state between the second electrode and the third terminal, a capacitor, and a reading circuit including a transimpedance amplifier; the second switch and the capacitor are connected in parallel with each other to the second electrode; the second switch, the second electrode, and the third terminal are connected in series with each other; the transimpedance amplifier is connected in series with the capacitor and is connected to the second electrode via the capacitor; and an absolute value of a potential difference between the first potential and the third potential is smaller than an absolute value of a potential difference between the first potential and the second potential.
  2. 2 . The photodetection device according to claim 1 , wherein, in each of the photodetection units, the first switch is connected to the second electrode via the resistor.
  3. 3 . The photodetection device according to claim 1 , further comprising a switch control unit configured to control the connection states by the first and second switches according to timing of photodetection in each of the photodetection units.
  4. 4 . The photodetection device according to claim 3 , wherein the switch control unit causes the second switch to connect the second electrode and the third terminal to each other in a state in which the first switch disconnects the second electrode and the second terminal from each other.
  5. 5 . The photodetection device according to claim 3 , wherein the switch control unit causes the second switch to disconnect the second electrode and the third terminal from each other in a state in which the first switch connects the second electrode and the second terminal to each other.
  6. 6 . The photodetection device according to claim 3 , further comprising an irradiation unit configured to apply light, wherein the switch control unit controls an energized state of each of the first and second switches according to timing when the light is applied from the irradiation unit.
  7. 7 . A photodetection device comprising a plurality of photodetection units each having a light reception region, wherein: each of the photodetection unit includes: an avalanche photodiode including first and second electrodes and forming the light reception region; a first terminal connected to the first electrode and to which a first potential is applied; first and second circuit units connected in parallel with each other to the second electrode; a second terminal connected to the second electrode via the first circuit unit and to which a second potential is applied; and a third terminal connected to the second electrode via the second circuit unit and to which a third potential is applied, and in each of the photodetection units: the first circuit unit includes a resistor and a switch for switching a connection state between the second electrode and the second terminal; the switch, the resistor, the second electrode, and the second terminal are connected in series with each other; the second circuit unit includes a diode, a capacitor, and a reading circuit including a transimpedance amplifier; the diode and the capacitor are connected in parallel with each other to the second electrode; the diode includes a third electrode having the same polarity as the first electrode of the avalanche photodiode and a fourth electrode having the same polarity as the second electrode of the avalanche photodiode; the third electrode of the diode is connected to the third terminal; the fourth electrode of the diode is connected to the second electrode; the transimpedance amplifier is connected in series with the capacitor and is connected to the second electrode via the capacitor; and an absolute value of a potential difference between the first potential and the third potential is smaller than an absolute value of a potential difference between the first potential and the second potential.
  8. 8 . The photodetection device according to claim 7 , wherein, in each of the photodetection units, the switch is connected to the second electrode via the resistor.
  9. 9 . The photodetection device according to claim 1 , wherein the transimpedance amplifier is included in a CMOS logic integrated circuit.
  10. 10 . The photodetection device according to claim 1 , wherein the resistor has impedance greater than input impedance of the second circuit unit.
  11. 11 . The photodetection device according to claim 1 , wherein the potential difference between the first potential and the second potential and the potential difference between the first potential and the third potential are included in a range of an operating voltage of the transimpedance amplifier.
  12. 12 . A photodetection device comprising: an avalanche photodiode including first and second electrodes; a first terminal connected to the first electrode; first and second circuit units connected in parallel with each other to the second electrode; a second terminal connected to the second electrode via the first circuit unit; and a plurality of photodetection units each including a third terminal connected to the second electrode via the second circuit unit, wherein, in each of the photodetection units: the first circuit unit includes a resistor and a first switch for switching a connection state between the second electrode and the second terminal; the first switch, the resistor, the second electrode, and the second terminal are connected in series with each other; the second circuit unit includes a second switch for switching a connection state between the second electrode and the third terminal, a capacitor, and a reading circuit including a transimpedance amplifier; the second switch and the capacitor are connected in parallel with each other to the second electrode; the second switch, the second electrode, and the third terminal are connected in series with each other; and the transimpedance amplifier is connected in series with the capacitor and is connected to the second electrode via the capacitor.
  13. 13 . A photodetection device comprising: an avalanche photodiode including first and second electrodes; a first terminal connected to the first electrode; first and second circuit units connected in parallel with each other to the second electrode; a second terminal connected to the second electrode via the first circuit unit; and a plurality of photodetection units each including a third terminal connected to the second electrode via the second circuit unit, wherein, in each of the photodetection units: the first circuit unit includes a resistor and a switch for switching a connection state between the second electrode and the second terminal; the switch, the resistor, the second electrode, and the second terminal are connected in series with each other; the second circuit unit includes a diode, a capacitor, and a reading circuit including a transimpedance amplifier; the diode and the capacitor are connected in parallel with each other to the second electrode; the diode includes a third electrode having the same polarity as the first electrode of the avalanche photodiode and a fourth electrode having the same polarity as the second electrode of the avalanche photodiode; the third electrode of the diode is connected to the third terminal; the fourth electrode of the diode is connected to the second electrode; and the transimpedance amplifier is connected in series with the capacitor and is connected to the second electrode via the capacitor.

Description

TECHNICAL FIELD The present invention relates to a photodetection device. BACKGROUND ART A photodetection device including a plurality of light reception regions has been known (for example, Patent Literature 1). In Patent Literature 1, a field effect transistor is connected in series with a photodiode that forms a light reception region. An energized state of the photodiode is switched by a switch using this field effect transistor. As a result, the photodiode to be used is selected. CITATION LIST Patent Literature Patent Literature 1: Japanese Unexamined Patent Publication No. 2018-44923 SUMMARY OF INVENTION Technical Problem When an avalanche photodiode is used as a photodiode forming a light reception region, a bias voltage is applied to the avalanche photodiode. When light enters the avalanche photodiode while the bias voltage is being applied, the avalanche photodiode multiplies and outputs electrons generated in response to the incident light. At this time, the avalanche photodiode generates heat. As the bias voltage increases, the amount of heat generated by the avalanche photodiode increases. As the number of avalanche photodiodes in a photodetection device increases, the amount of heat generated in the photodetection device increases. In a photodetection device that uses a plurality of avalanche diodes, there is a risk that detection accuracy will decrease due to heat generation in each avalanche photodiode. Depending on the number of avalanche photodiodes in the photodetection device, the value of the bias voltage, and the amount of incident light, the photodetection device may be damaged by the heat generation. Even when light to be measured is not incident, the avalanche photodiode can generate heat due to incidence of environmental light such as sunlight. Therefore, it is conceivable to suppress the heat generation by stopping application of the bias voltage to an avalanche photodiode which the light to be measured does not enter. For example, in the photodetection device disclosed in Patent Literature 1, application of the bias voltage to the photodiode is stopped by breaking electrical connection to the photodiode that forms the light reception region. Specifically, a switch connected in series with the photodiode is switched between a conductive state and a cutoff state. In the conductive state, in which the switch is conducting, the bias voltage is applied to the avalanche photodiode. In the cutoff state, in which the switch is cut off, no bias voltage is applied to the avalanche photodiode. In this photodetection device, a voltage corresponding to the bias voltage applied to the avalanche photodiode is applied to a reading circuit for reading a signal from the avalanche photodiode. Therefore, even when the heat generation is suppressed, the reading circuit in the photodetection device may be damaged due to fluctuation in a potential applied to the reading circuit in response to switching between the conductive state and the cutoff state by the switch. An object of each aspect of the invention is to provide a photodetection device capable of suppressing heat generation of an avalanche photodiode due to incident light and damage to a reading circuit due to voltage fluctuation. Solution to Problem A photodetection device in one aspect of the invention includes a plurality of photodetection units each having a light reception region. Each of the photodetection unit includes an avalanche photodiode, a first terminal, first and second circuit units, a second terminal, and a third terminal. The avalanche photodiode includes first and second electrodes and forms the light reception region. The first terminal is connected to the first electrode. A first potential is applied to the first terminal. The first circuit unit and the second circuit unit are connected in parallel with each other to the second electrode. The second terminal is connected to the second electrode via the first circuit unit. A second potential is applied to the second terminal. The third terminal is connected to the second electrode via the second circuit unit. A third potential is applied to the third terminal. In each of the photodetection units, the first circuit unit includes a first switch and a resistor, and the second circuit unit includes a second switch, a capacitor, and a reading circuit. The first switch switches a connection state between the second electrode and the second terminal. The first switch, the resistor, the second electrode, and the second terminal are connected in series with each other. The second switch switches a connection state between the second electrode and the third terminal. The reading circuit includes a transimpedance amplifier. The second switch and the capacitor are connected in parallel with each other to the second electrode. The second switch, the second electrode, and the third terminal are connected in series with each other. The transimpedance amplifier is connected in series with t