Thin Film Electronics Asa

Per Sandström

Hans Gude Gudesen

Per-Erik Nordal

Mats Johansson

Geirr Ivarsson Leistad

Christer Karlsson

Göran Gustafsson

Johan Carlsson

Per Bröms

In a method for operating a passive matrix-addressable ferroelectric or electret memory device, a voltage pulse protocol based on a 1/3 voltage selection rule is used in order to keep disturb voltages at minimum, the voltage pulse protocol comprising cycles for read and write/erase bases on time sequence of voltage pulses with defined parameters. The method comprises a refresh procedure wherein cells for refresh are selected and refresh requests processed by a memory device controller, the refresh requests are monitored and processed in regard of ongoing or scheduled memory operations, and refresh voltage pulses with defined parameters are applied to the memory cells selected for refresh, while simultaneously ensuring that non-selected memory cells are subjected to zero voltage or voltages which do not affect the polarization state of these cells.

Method for operating a passive matrix-addressable ferroelectric or electret memory device

A matrix-addressable ferroelectric or electret memory device and a method of operating are explained. The method includes applying a first plurality of voltage difference across a first and a second set of electrodes in the memory when data are read, and applying a second plurality of voltage differences when data are refreshed or rewritten. The first and second plurality of voltage differences correspond to sets of potential levels comprising time sequences of voltage pulses. At least one parameter indicative of a change in a memory cell response is used for determining at least one correction factor for the voltage pulses, whereby the pulse parameter is adjusted accordingly. The memory device comprises means for determining the at least one parameter, a calibration memory connected with means for determining the correction factor, and control circuits for adjusting pulse parameters as applied to read and write operations in the memory device.

Method for operating a ferroelectric of electret memory device, and a device of this kind

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Linköping, Sweden

Per Sandström