An analog to digital converter comprises an input for receiving an analog input signal; a plurality of outputs for outputting parallel bits of a digital signal that represents said analog input signal; and a neural network layer providing connections between each of said outputs respectively, each connection having an adjustable weighting. The synapses of the neural networks may be memristors and training may use online gradient descent.

An analog to digital converter comprises an input for receiving an analog input signal; a plurality of outputs for outputting parallel bits of a digital signal that represents said analog input signal; and a neural network layer providing connections between each of said outputs respectively, each connection having an adjustable weighting. The synapses of the neural networks may be memristors and training may use online gradient descent.