Non-volatile memory with temperature-compensated data read
AssigneeSanDisk Corporation
InventorRaul-Adrian Cernea
Life of this patent
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Abstract
A novel non-volatile memory is disclosed. The non-volatile memory includes an array of data storage cells that individually include a storage element such as a floating gate, a control gate and first and second source/drain terminals. A current source provides a current to the first source/drain terminal of the data storage element. A node is electrically connected to the second source/drain terminal of the data storage element. A bias circuit provides a bias voltage to the node. The bias voltage varies with temperature in a manner approximately inverse to the thermal variation of the threshold voltage of the data storage element. A control gate voltage circuit provides a voltage level to the control gate of the data storage cell.
Claims12
A non-volatile memory, comprising:
- a data storage cell including a storage element, a control gate and first and second source/drain terminals;
- a first current source operable to provide a first current to the first source/drain terminal;
- a node electrically connected to the second source/drain terminal;
- a bias circuit operable to provide a bias voltage to the node, the bias voltage varying with temperature, the variation of the bias voltage being approximately inverse to a thermal variation of a threshold voltage of the data storage cell;
- and
- a control gate voltage circuit operable to provide a voltage level to the control gate.
A non-volatile memory comprising:
- means for storing data, the means comprising a charge storage element, a control ate and first and second source/drain terminals;
- means for providing a first current to the first source/drain terminal of the data storage means;
- means for providing a bias voltage to the second source/drain terminal of the data storage means, the bias voltage varying with temperature, the variation of the bias voltage being approximately inverse to a thermal variation of a threshold voltage of the data storage means;
- and
- means for providing a voltage level to the control gate of the data storage element.
A method for reading stored data from a non-volatile memory, comprising:
- conducting a first current through a first source/drain terminal of an EEPROM transistor, the EEPROM transistor having a second source/drain terminal coupled to a node;
- conducting current through the node by a current source;
- providing a thermally invariant bias voltage to a gate of a transistor, the transistor having a source/drain terminal coupled to the node, the transistor conducting at least a portion of the current being passed through the node by the current source;
- providing a voltage to a control gate of the EEPROM transistor;
- and
- detecting a voltage at the first source/drain terminal of the EEPROM transistor.
A method of operating an array of non-volatile memory cells that individually have at least one storage element positioned over at least a portion of a channel between source/drain terminals and a control gate coupled with said at least one storage element, comprising:
- addressing one or more of the cells for simultaneously reading or programming data therein,
- applying a level of electrical supply to at least one of the source/drain terminals of the addressed cells that varies as a function of a temperature of the memory cell array, and
- applying a set of voltages to the control gates of the addressed cells that are independent of the temperature of the memory cell array.
Dependencies are inferred from the claim text.