Hybrid leakage-compensation scheme for improved correction range

Abstract

A dark current compensation circuit comprises a first comparator having inputs for a detection signal and a first voltage, and a second comparator having inputs for the detection signal and a second voltage. The dark current compensation circuit also comprises a controller coupled to the first and second comparators, which has an input for an event signal. An adjustable current source is coupled to the controller and configured to generate a compensation current. The controller adjusts a value of the compensation current based on the first and second comparator outputs and maintains a constant value in response to the event signal indicating photons incident on a photon detector. In some implementations, the dark current compensation circuit further comprises an analog sub-circuit coupled to the adjustable current source and configured to receive the detection signal. The analog sub-circuit generates an analog compensation current in response to the detection signal.

What is claimed is: 
     
         1 . A method, comprising:
 receiving a detection signal;   comparing the detection signal to an upper voltage threshold and a lower voltage threshold;   generating a compensation signal based on the comparison; and   maintaining a constant compensation signal based on an event signal.   
     
     
         2 . The method of  claim 1 , wherein the detection signal represents photons from a photon sensor. 
     
     
         3 . The method of  claim 1 , wherein the event signal is indicative of photons incident on a photon detector, wherein the compensation signal is generated based on the comparison until the event signal indicates photons incident on a photon detector, and wherein the constant compensation signal is maintained in response to the event signal indicating photons incident on a photon detector. 
     
     
         4 . The method of  claim 1 , wherein a processing unit maintains a constant output without adjustment in response to the event detection signal indicating photons incident on a photon detector. 
     
     
         5 . The method of  claim 1 , wherein an analog sub-circuit is configured to generate an analog compensation current based on the detection signal.