1. A neural network comprising: a plurality of capacitors for storing weighted electric charges, an input terminal for receiving weighted voltages appearing in serial form, a plurality of controlled semiconductor gating elements coupling individual respective ones of said capacitors to said input terminal, a plurality of controlled semiconductor variable impedance elements having individual control terminals coupled respectively to individual ones of said capacitors, the impedance value of each of said variable impedance elements being determined by the voltage on its individually coupled capacitor, at least one summing amplifier having an input coupled to given ones of said variable impedance elements, said summing amplifier having an output coupled to an output of the neural network, a plurality of further input terminals for receiving input signals and coupled to individual ones of said variable impedance elements, and means coupled to control electrodes of said semiconductor gating elements for sequentially energizing the gating elements to refresh the weighted electric charges stored on the capacitors by means of the weighted voltages appearing at said input terminal.