Harris Corporation

Ronald G Neale

Grady M Wood

The Write/Erase lifetime of amorphous memory devices are extended by applying an erase pulse sequence having a first plurality of reset voltage pulses having a maximum amplitude less than the maximum threshold of the device to produce first amplitude current pulses and a second plurality of reset voltage pulses having a maximum amplitude greater than the maximum threshold to produce second amplitude current pulses having an amplitude substantially less than said current pulses. Constant current sources apply the two current pulses when the device threshold is below the maximum voltage amplitude of the first reset voltage pulses and only the second amplitude current pulses when the device threshold exceeds the maximum voltage amplitude of the first reset voltage pulses.

Multilevel sequence of erase pulses for amorphous memory devices

The Write/Erase lifetimes of amorphous memory devices are extended by applying a multilevel erase pulse wherein the first stage has a current amplitude sufficient to heat the crystal filament to the phase change temperature but not to provide the energy for the phase change and erasure of the crystal structure and the second stage has a current amplitude sufficient to heat the filament to remove the crystal structure. Preferably the first stage current is equal to the write current and the second stage is equal to the write current times the ratio of the electrical conductivity of the amorphous conducting state to the apparent conductivity of the crystalline state.

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Carshalton Beeches, United Kingdom

Ronald G Neale