Abstract: A method for analog-to-digital conversion with reconfigurable function mapping for acceleration of calculating an activation function of a neural network system includes determining, by a shared circuit, a set of voltage intervals using digital bits in a look-up table to define a shape of the activation function being mapped. The shared circuit determines a set of most significant bits (MSBs) for each voltage interval by storing additional bits in the look-up table corresponding to each voltage interval entry. Further, each of several per-neuron circuits determines whether its accumulated input voltage is in a received voltage interval, and if so, causing the set of MSBs to be stored. Each of the per-neuron circuits determines a set of least significant bits (LSBs) by performing a linear interpolation over the voltage interval. The set of MSBs and the set of LSBs are output as a result of the activation function with analog-to-digital conversion.