Linear regulation of SPAD shutoff voltage
AssigneeSTMicroelectronics (Research & Development) Limited
InventorJohn Kevin Moore
Life of this patent
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Abstract
Described herein is an electronic device, including a pixel and a turn-off circuit. The pixel includes a single photon avalanche diode (SPAD) having a cathode coupled to a high voltage node and an anode selectively coupled to ground through an enable circuit, and a clamp diode having an anode coupled to the anode of the SPAD and a cathode coupled to a turn-off voltage node. The turn-off circuit includes a sense circuit coupled between the turn-off voltage node and ground and configured to generate a feedback voltage, and a regulation circuit configured to sink current from the turn-off voltage node to ground based upon the feedback voltage such that a voltage at the turn-off voltage node maintains generally constant.
Claims16
An electronic device, comprising:
- a pixel comprising:
- a single photon avalanche diode (SPAD) having a cathode coupled to a high voltage node, and an anode selectively coupled to ground through an enable circuit;
- and
- a clamp diode having an anode coupled to the anode of the SPAD and a cathode coupled to a turn-off voltage node;
- and
- a turn-off circuit comprising:
- a sense circuit coupled between the turn-off voltage node and ground and configured to generate a feedback voltage;
- and
- a regulation circuit configured to sink current from the turn-off voltage node to ground based upon the feedback voltage such that a voltage at the turn-off voltage node maintains generally constant.
A turn-off circuit for a single photon avalanche diode (SPAD) pixel, comprising:
- a turn-off voltage node receiving a photocurrent from the SPAD pixel when the SPAD pixel is in a non-avalanche mode of usage;
- and
- a regulation circuit configured to sink a current from the turn-off voltage node that is proportional to the photocurrent such that a voltage at the turn-off voltage node remains generally constant regardless of a value of the photocurrent.
A method, comprising:
- causing a single photon avalanche diode (SPAD) to generate a photocurrent while not avalanching;
- and
- maintaining an anode of the SPAD at a turn-off voltage sufficient to keep the SPAD from being in an avalanchable condition by:
- flowing a constant current through a resistive divider to provide the turn-off voltage;
- permitting the photocurrent to flow through the resistive divider;
- and
- reducing the constant current proportionally to a value of the photocurrent such that the turn-off voltage stays substantially constant regardless of the value of the photocurrent.
Dependencies are inferred from the claim text.