A digital signal may be converted into a spiking analog signal. A different constant current may be applied to each of a plurality of switch circuits. Each bit of the digital signal may be applied to a corresponding one of the plurality of switch circuits. Each switch circuit may apply the corresponding constant current to a common output when the corresponding bit has a predetermined value. Each switch circuit may not apply the corresponding constant current to the common output when the corresponding bit does not have the predetermined value. A common current may be applied at the common output to a spiking neuron circuit.