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

US7215565B2 · kind B2 · utility

Assignee

• Thin Film Electronics ASA · NO

Inventors

• Christer Karlsson · Linköping, SE
• Goran Gustafsson · Säter, SE
• Mats Johansson · Säter, SE
• Per Sandström · Säter, SE
• Per-Erik Nordal · Asker, NO
• Hans Gude Gudesen · Fredrikstad, NO
• Johan Carlsson · Cologne, DE

Key dates

• Filing date: Jan 4, 2005
• Grant date: May 8, 2007
• Expiry date: Jun 24, 2025

Classification

• Technology area (CPC G): Physics
• CPC primary: G11C11/22
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

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.