Patent ID: 6937500

Claim:
A method for operating a ferroelectric or electret memory device, wherein the memory device comprises memory cells in the form of a ferroelectric or electret thin-film polarizable material exhibiting hysteresis, particularly a ferroelectric or electret polymer thin film, and a first and a second set of respective parallel electrodes, wherein the electrodes of the first set are provided in substantially orthogonal relationship to the electrodes of the second set, wherein the electrodes of said first and second set are provided in direct or indirect contact with the thin-film material of the memory cells, whereby a polarization state in individual memory cells can be read, refreshed, erased or written by applying appropriate voltages to the individual electrodes of respectively said first and second set of electrodes, wherein the method implements a voltage pulse protocol comprising a read and write/refresh cycle respectively with time sequences of voltage pulses of predefined amplitudes and lengths, wherein a read cycle comprises applying a set of voltage differences to electrodes of respectively said first and second set of electrodes in case data are read out from the memory cells, wherein the write/refresh cycle of the voltage pulse protocol comprises applying another set of voltage differences to electrodes of respectively said first and second set of electrodes in case data are written/refreshed to said memory cells, said sets of voltage differences corresponding to a predefined set of potential levels such that the predefined set of potential levels has at least three separate values, the method comprising: a) determining at least one parameter indicative of a change in a memory cell response to the applied voltage differences; b) determining at least one correction factor for the voltage pulses as given by the voltage pulse protocol on the basis of said at least one parameter indicative of the change in a memory cell response to the applied voltage differences; c) selecting for an adaptation of the voltage pulse protocol at least one of the following pulse protocol parameters, viz. pulse amplitudes, pulse lengths and pulse intervals; and d) adjusting one or more parameter values of at least one of said selected pulse protocol parameters in accordance with said at least one correction factor, whereby one or more pulse amplitudes, one or more pulse lengths, and one or more pulse intervals are adjusted either separately or in combination in accordance with a detected change in the memory cell response.