An analysis of the information efficiency of single photon avalanche diodes

In this work, we model single photon avalanche diodes (SPADs) as communication channels. We apply classical Shannon results for a Gaussian channel to typical SPAD circuits. Thus we look at the information rate and the bit energy of the circuit. By considering the noise sources for a generic SPAD sensor we develop the information rate model as a function of the excess bias voltage and perimeter gate voltage. We find that when considering only the dark count rate that there is a single optimum excess bias voltage that gives the maximum information rate. We conclude there is an excess voltage, gate voltage pair that optimizes the information rate.