The present invention is a Silicon PhotoMulitplier comprising a plurality of photon detection cell clusters each comprising a plurality of avalanche photodiodes connected in parallel, so that the output of each avalanche photodiode is summed together and applied to a cell cluster output. Each of the plurality of cell cluster outputs is connected to one of a plurality of cluster readout circuits, each of which includes an analog to digital converter that converts an analog representation of the total energy received by a photon detection cell cluster to a digital energy signal. A SiPM Pixel reader circuit is connected to the plurality of cluster readout circuits and configured to generate an overall pixel output by digital processing the plurality of digital energy signals received from the plurality of photon detection cell clusters by way of the plurality of cluster readout circuits. The SIPM pixel reader circuit also receives digital signals representative of timing triggers and the total energy received by a specific photon detection cell cluster and generates an overall SiPM energy signal and overall timing trigger in response to the signals received from the plurality of cluster readout circuits.