Memory device and method of operating same
AssigneeSilicon Storage Technology, Inc.
InventorBomy Chen
Life of this patent
Estimating the term…
Abstract
An array of phase changing memory cells that includes a current source, a voltage sensor, a plurality of conductive bit lines electrically connected to the current source, a plurality of conductive word lines each electrically connected to a ground plane via a first resistor and to the voltage sensor, and a plurality of memory cells. Each memory cell is connected between one of the bit lines and one of the word lines and includes phase change memory material. One of the memory cells is selected by turning on switches just on the bit line and word line connected thereto, or by turning a switch connected in series between the corresponding bit and word lines, where the read current flows through the selected memory cell and the voltage sensor measures a voltage drop across the selected memory cell.
Claims26
An array of phase change memory cells, comprising:
- a current source for supplying a read electrical current;
- a voltage sensor;
- a plurality of conductive bit lines each electrically connected to the current source via a first on/off switch;
- a plurality of conductive word lines each electrically connected to a voltage source via a second on/off switch and a first resistor, and to the voltage sensor;
- a plurality of memory cells, each including:
- a first electrode directly electrically connected to one of the bit lines,
- a second electrode directly electrically connected to one of the word lines, and
- phase change memory material disposed in electrical contact with the first and second electrodes;
- and
- a reference voltage source connected to the voltage sensor.
An array of phase change memory cells, comprising:
- a current source for supplying a read electrical current;
- a voltage sensor;
- a plurality of conductive bit lines each electrically connected to the current source;
- a plurality of conductive word lines each electrically connected to a voltage source via a first resistor, and to the voltage sensor;
- a plurality of memory cells, each including:
- a first electrode directly electrically connected to one of the bit lines,
- a second electrode directly electrically connected to one of the word lines,
- phase change memory material disposed in electrical contact with the first and second electrodes, and
- a first on/off switch included in the direct electrical connection between the first electrode and the one bit line or the direct electrical connection between the second electrode and the one word line;
- and
- a reference voltage source connected to the voltage sensor.
A method of operating a memory cell array having a current source for supplying electrical current, a voltage sensor, a plurality of conductive bit lines each electrically connected to the current source via a first on/off switch, a plurality of conductive word lines each electrically connected to a voltage source via a second on/off switch and a first resistor and to the voltage sensor, a reference voltage source, and a plurality of memory cells, wherein each of the memory cells includes a first electrode directly electrically connected to one of the bit lines, a second electrode directly electrically connected to one of the word lines, and a phase change memory material disposed in electrical contact with the first and second electrodes, the method comprising:
- selecting one of the memory cells by turning on the first and second on/off switches for the bit and word lines directly electrically connected thereto;
- supplying a read electrical current from the current source to the bit line directly electrically connected to the selected memory cell, wherein the read electrical current flows through the selected memory cell and produces a first voltage on the word line directly electrically connected thereto;
- supplying a reference voltage from the reference voltage source;
- and
- measuring and comparing the first voltage and the reference voltage using the voltage sensor.
A method of operating a memory cell array having a current source for supplying electrical current, a voltage sensor, a plurality of conductive bit lines each electrically connected to the current source, a plurality of conductive word lines each electrically connected to a voltage source via a first resistor and to the voltage sensor, a reference voltage source, and a plurality of memory cells, wherein each of the memory cells includes a first electrode directly electrically connected to one of the bit lines, a second electrode directly electrically connected to one of the word lines, a phase change memory material disposed in electrical contact with the first and second electrodes, and a first on/off switch included in the direct electrical connection between the first electrode and the one bit line or the direct electrical connection between the second electrode and the one word line, the method comprising:
- selecting one of the memory cells by turning on the first on/off switch for the selected memory cell;
- supplying a read electrical current from the current source to the bit line directly electrically connected to the selected memory cell, wherein the read electrical current flows through the selected memory cell and produces a first voltage on the word line directly electrically connected thereto;
- supplying a reference voltage from the reference voltage source;
- and
- measuring and comparing the first voltage and the reference voltage using the voltage sensor.
Dependencies are inferred from the claim text.