Proximity sensor and method of operating a photodetector based proximity sensor

A method for detecting pile-up within circuitry associated with photodetectors, the method comprising:

• receiving a plurality of photodetector outputs;
• combining the photodetector outputs;
• counting the combining of the photodetector outputs;
• comparing the counting of the combining to a determined threshold value;
• and
• generating an indicator based on the comparing, wherein the indicator indicates pile-up within the circuitry associated with photodetectors when the counting of the combining is greater than or equal to the determined threshold value.

An apparatus for detecting pile-up within circuitry associated with photodetectors, the apparatus comprising:

• means for receiving a plurality of photodetector outputs;
• means for combining the photodetector outputs;
• means for counting the combining of the photodetector outputs;
• means for comparing the counting to a determined threshold value;
• and
• means for generating an indicator based on the comparing, wherein the indicator indicates pile-up within the circuitry associated with photodetectors when the counting is greater than or equal to the determined threshold value.

An apparatus comprising:

• a plurality of avalanche diode comparators configured to output signals from an associated plurality of avalanche diodes;
• a plurality of pulse shapers, each pulse shaper having an input coupled to an output of an associated avalanche diode comparator;
• a main OR-tree having a plurality of inputs, each input of the main OR-tree being coupled to an output of an associated one of the pulse shapers;
• a fast time to digital converter (TDC) having an input coupled to an output of the main OR-tree;
• a pile-up OR-tree having a plurality of inputs, each input of the pile-up OR-tree being coupled to an output of an associated avalanche diode comparator;
• a counter having an input coupled to an output of the pile-up OR-tree;
• and
• a comparator having a first input coupled to an output of the counter and a second input coupled to a threshold signal node.