A multi-pixel photomultiplier optical sensor may include an array of photomultiplier dies. Each photomultiplier die may include a front side connection pad, SPAD cells, each SPAD cell including a front side electrode, a rear side electrode, and a resistor coupled in series to the front side electrode and coupled in common with other quenching resistors to the front side connection pad. The multi-pixel photomultiplier optical sensor may include a metallization layer in contact with the rear side electrode common to SPADs of the array of photomultiplier dies and electrically conductive pads. The electrically conductive bus may be coupled to an electrically conductive pin for distributing bias current to the array of photomultiplier dies. The multi-pixel photomultiplier optical sensor may include electrically conductive bond wires coupling at least some of the electrically conductive pads to the electrically conductive bus, and distributing bias current to the array of photomultiplier dies via the electrically conductive bus.