Single photon avalanche diode (SPAD) with variable quench resistor

An integrated circuit, comprising:

• a semiconductor substrate that is relatively lightly doped with a first conductivity type dopant;
• an insulating wall that delimits, within the semiconductor substrate, a first semiconductor region, a second semiconductor region and a third semiconductor region, wherein the first, second and third semiconductor regions are insulated from each other by said insulating wall;
• a first well within the first semiconductor region that is doped with a second conductivity type dopant and configured to form a first photosensitive diode;
• a second well at an upper surface of the semiconductor substrate within the second semiconductor region that is relatively heavily doped with the first conductivity type dopant to form a first terminal;
• a third well at an upper surface of the semiconductor substrate within the second semiconductor region that is relatively heavily doped with the first conductivity type dopant to form a second terminal;
• wherein the third well is separated from the second well by a portion of the second semiconductor region to form a first quench resistor that is electrically connected to the first photosensitive diode through one of the first and second terminals;
• and
• a fourth well at an upper surface of the semiconductor substrate within the third semiconductor region that is relatively heavily doped with the first conductivity type dopant to form a first gate terminal configured to modulate a resistance of the first quench resistor.

An integrated circuit, comprising:

• a photosensitive diode having an anode terminal and a cathode terminal;
• and
• a passive quench resistance circuit having a variable resistance controlled by a control signal;
• wherein said passive quench resistance circuit comprises:
• a first semiconductor region of a semiconductor substrate that is doped with a first conductivity type dopant at a first concentration level and including a first resistor terminal and a second resistor terminal, the first and second resistor terminals separated from each other by a portion of the first semiconductor region forming a resistor;
• wherein one of the first and second resistor terminals is electrically connected to the cathode terminal of the photosensitive diode;
• and
• a second semiconductor region of the semiconductor substrate that is doped with the first conductivity type dopant at a second concentration level higher than the first concentration level, said second semiconductor region insulated from the first semiconductor region and extending parallel to the first semiconductor region to form a control gate configured to receive said control signal with a voltage that controls said variable resistance.

An integrated circuit, comprising:

• a photosensitive diode having an anode terminal and a cathode terminal;
• and
• a passive quench resistance circuit having a variable resistance controlled by a control signal;
• wherein said passive quench resistance circuit comprises:
• a semiconductor region of a semiconductor substrate that is doped with a first conductivity type dopant at a first concentration level and including a first resistor terminal and a second resistor terminal, the first and second resistor terminals separated from each other by a portion of the first semiconductor region forming a resistor;
• wherein one of the first and second resistor terminals is electrically connected to the cathode terminal of the photosensitive diode;
• and
• a conductive deep trench isolation structure insulated from the first semiconductor region and extending parallel to the first semiconductor region to form a control gate configured to receive said control signal with a voltage that controls said variable resistance.