Stmicroelectronics S.r.l.

Giampiero Sberno

Nicolas Demange

Salvatore Torrisi

Antonino Conte

Enrico Castaldo

Gianbattista Lo Giudice

Mario Micciche

Mario Micciche'

Alberto Jose Di Martino

A generator circuit generates a reference voltage on an output terminal connected to a matrix of non-volatile memory cells and includes a comparator positioned between a common node and the output terminal. The comparator has first and second input terminals and an output terminal suitable for supplying a compared voltage given by comparing first and second voltage values present on the first and second input terminals. The circuit includes a reference cell inserted between the common node and a first voltage reference. Advantageously, the reference cell comprises a floating gate with a contact terminal coupled to a biasing block, having an input terminal connected to the output terminal of the generator circuit and being suitable for periodically biasing the floating gate contact terminal at a biasing voltage of a second voltage reference.

Circuit and method for generating a reference voltage in memory devices having a non-volatile cell matrix

A non-volatile memory device is proposed. The memory device includes a plurality of blocks of memory cells, each block having a common biasing node for all the memory cells of the block, biasing means for providing a biasing voltage, and selection means for selectively applying the biasing voltage to the biasing node of a selected block, for each block the selection means including first switching means and second switching means connected in series, the first switching means being connected with the biasing node and the second switching means being connected with the biasing means, wherein the second switching means of all the blocks are connected in parallel, the selection means including means for closing the first switching means of the selected block and the second switching means of all the blocks, and for opening the second switching means of each unselected block.

Discharge circuit for a word-erasable flash memory device

A circuit for sensing a ferroelectric non-volatile information storage unit comprises a pre-charge circuit for applying a prescribed pre-charge voltage to a storage capacitor of the information storage unit. The pre-charge voltage causes a variation in a polarization charge of the storage capacitor, depending on an initial polarization state of the storage capacitor. A charge integration circuit integrates an electric charge proportional to the variation in polarization charge experienced by the storage capacitor. The charge integration circuit thus provides an output voltage depending on the polarization state of the storage capacitor. The charge integration circuit may comprises an integration capacitor and current mirror circuit, with a first mirror branch coupled to the pre-charge circuit and a second mirror branch coupled to the integration capacitor, for mirroring into the second mirror branch an electric charge supplied to the information storage unit to compensate for the variation in the polarization charge experienced by the storage capacitor.

Sensing circuit for ferroelectric non-volatile memories

A ferroelectric semiconductor memory includes an arrangement of memory units comprising at least one row of memory units. The memory units of the at least one row are associated with a respective word line of the arrangement. The arrangement of memory unit includes a plurality of local word lines branching off from the word line associated with the at least one row, each local word line being connected to a respective group of memory units of the line. Selective connection means allow to selectively connect one of the local word lines to the respective word line. The arrangement of memory units further includes a plurality of local plate biasing lines, each one associated with the memory units of a respective group of memory units, for selectively driving the memory units of the respective groups.

FeRAM semiconductor memory

A method and circuit for accessing a memory location comprising at least one respective ferroelectric storage unit of a matrix of ferroelectric storage units, the memory location is selected by connecting a first terminal of a ferroelectric storage element of the at least one respective storage unit to a respective access line to the memory location; at least another memory location to which is not intended to be accessed is also selected. A second terminal of the ferroelectric storage element is biased to a prescribed access electric potential, and an electric potential on the access line is sensed; the second terminal of the ferroelectric storage elements of the other memory location is also biased to the access potential.

Method and related circuit for accessing locations of a ferroelectric memory

A method of sensing a ferroelectric non-volatile information storage unit comprising two ferroelectric storage capacitors in mutually opposite polarization states, and a sensing circuit for actuating the method. The method comprises the steps of: making a voltage applied across the two storage capacitors substantially zero; starting from this condition, progressively increasing the voltage applied thereacross by supplying a prescribed current, until a first one of the two storage capacitors approaches a condition of polarization state reversal, thereby the voltage applied across said first storage capacitor starts to decrease with respect to the voltage applied across the second storage capacitor; and amplifying a voltage difference between the voltages applied across the two storage capacitors by making the voltage applied across the first storage capacitor substantially zero and the voltage applied across the second storage capacitor substantially equal to a non-zero voltage corresponding to a logic state opposite to a logic state corresponding to the zero voltage.

Low fatigue sensing method and circuit for ferroelectric non-volatile storage units

A method of reading and restoring data stored in a ferroelectric memory cell is disclosed. The cell includes a first transistor and first ferroelectric capacitor connected, in series with each other, between a first bitline and an auxiliary line, a second transistor and second ferroelectric capacitor connected, in series with each other, between a second bitline and the auxiliary line, the first and second transistors having respective control terminals connected to a common wordline. The reading method includes precharging the first and second capacitors, applying a read pulse to the cell such that the state of the first capacitor is changed, reading the cell by a sensing means, and restoring the first capacitor to an initial state. Advantageously, the reading method further includes changing the state of the second capacitor during the step of restoring the first capacitor, and further restoring the second capacitor to an initial state, such that the voltages being applied to the transistors during any of the steps are lower than a voltage reference of the cell. Also disclosed is a method of writing and restoring data stored in a ferroelectric memory cell.

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Catania, Italy

Giampiero Sberno