Differential correlator filter for efficient ToF peak finding

A differential correlator filter comprising:

• a pre-pulse region, wherein first filter coefficients in the pre-pulse region have negative values;
• a pulse region comprising a rising edge region, a falling edge region, and an accumulation region in between, wherein second filter coefficients in the rising edge region, third filter coefficients in the accumulation region, and fourth filter coefficients in the falling edge region have positive values;
• and
• a post-pulse region, wherein the pulse region is between the pre-pulse region and the post-pulse region, wherein fifth filter coefficients in the post-pulse region have negative values.

A method of operating a time-of-flight (ToF) imager, the method comprising:

• sending out a light signal using a light source of the ToF imager;
• generating, by a single-photon avalanche diode (SPAD) of the ToF imager, a histogram based on a reflected light signal;
• and
• filtering the histogram using a differential correlator filter (DCF), wherein the DCF comprises:
• a pre-pulse region, wherein first filter coefficients in the pre-pulse region have negative values;
• a pulse region comprising:
• a rising edge region, wherein second filter coefficients in the rising edge region have positive values;
• an accumulation region, wherein third filter coefficients in the accumulation region have positive values;
• and
• a falling edge region, wherein fourth filter coefficients in the falling edge region have positive values, wherein the accumulation region is between the rising edge region and the falling edge region;
• and
• a post-pulse region, wherein the pulse region is between the pre-pulse region and the post-pulse region, wherein fifth filter coefficients in the post-pulse region have negative values.