SEMICONDUCTOR MEMORY DEVICE, METHOD OF OPERATING SEMICONDUCTOR MEMORY DEVICE, AND MEMORY SYSTEM

• US 20090245003A1
• Filed: 03/25/2009
• Published: 10/01/2009
• Est. Priority Date: 03/27/2008
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Fujitsu Microelectronics Limited (Fujitsu Limited)
• Inventors: ITO, Shigemasa
• Granted Patent: US 7,995,414 B2
• Time in Patent Office: Days
• US Class Current: 365/211
• CPC Class Codes: G11C 11/406 Management or control of the refreshing or charge-regeneration cycles
• CPC Class Codes: G11C 11/40626 Temperature related aspects of refresh operations
• CPC Class Codes: G11C 11/4091 Sense or sense/refresh amplifiers, or associated sense circuitry, e.g. for coupled bit-line precharging, equalising or isolating
• CPC Class Codes: G11C 2207/005 Transfer gates, i.e. gates coupling the sense amplifier output to data lines, I/O lines or global bit lines
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects
• CPC Class Codes: G11C 7/08 Control thereof

Abstract

A semiconductor memory device is provided which comprises: a sense amplifier; and a bit line, wherein the disconnection of the sense amplifier from the bit line is performed in a data read operation when temperature in the semiconductor memory device is at a first temperature, and wherein the disconnection of the sense amplifier from the bit line is not performed in the data read operation when the temperature in the semiconductor memory device is at a second temperature.

Claims

1. A semiconductor memory device comprising:

a sense amplifier; and

a bit line,

wherein disconnection of the sense amplifier from the bit line is performed during a data read operation when the temperature in the semiconductor memory device is at a first temperature, and

wherein the disconnection of the sense amplifier from the bit line is not performed in the data read operation when the temperature in the semiconductor memory device is at a second temperature.

2. The semiconductor memory device according to claim 1, wherein determining whether disconnection of the sense amplifier is performed is based on a control signal.

3. The semiconductor memory device according to claim 2, wherein the control signal is supplied from an outside source.

4. The semiconductor memory device according to claim 2, wherein the control signal is generated based on fuse breakage information.

5. The semiconductor memory device according to claim 1, wherein the first temperature is lower than the second temperature.

6. A semiconductor memory device comprising:

a disconnection circuit that disconnects a sense amplifier from a bit line in a data read operation;

a temperature sensing circuit that senses a temperature; and

a disconnection control circuit that controls disconnection by the disconnection circuit based on the temperature.

7. The semiconductor memory device according to claim 6, wherein the disconnection control circuit determines whether the disconnection is performed based on at least one of a control signal from an outside source and a control signal from a programmed circuit.

8. The semiconductor memory device according to claim 6, wherein the disconnection circuit includes a transistor that is controlled based on a disconnection control signal from the disconnection control circuit.

9. The semiconductor memory device according to claim 6, further comprising,

a disconnection prohibiting circuit that prohibits the disconnection irrespective of the temperature when a data read request conflicts with a refresh request.

10. The semiconductor memory device according to claim 6, wherein the temperature sensing circuit includes a trimming circuit that adjusts the temperature to be sensed.

11. The semiconductor memory device according to claim 10, further comprising,

a trimming control circuit that adjusts the trimming circuit based on an external control.

12. The semiconductor memory device according to claim 6, wherein the disconnection control circuit performs the disconnection when the temperature is lower than or equal to a certain temperature, and does not perform the disconnection when the temperature exceeds the certain temperature.

13. The semiconductor memory device according to claim 6, wherein the disconnection control circuit outputs a pulse signal for controlling the disconnection circuit, and changes waveform of the pulse signal based on the temperature.

14. A method of operating a semiconductor memory device, comprising:

activating a word line;

activating a disconnection control signal that disconnects a sense amplifier from a bit line when the temperature in the semiconductor memory device is a first temperature; and

prohibiting activation of the disconnection control signal that disconnects the sense amplifier from the bit line when the temperature in the semiconductor memory device is a second temperature.

15. The method according to claim 14, further comprising

detecting one of the first temperature and the second temperature.

16. The method according to claim 14, wherein the first temperature is lower than the second temperature.

17. The method according to claim 14, further comprising,

adjusting a timing of the disconnection based on one of the first temperature and the second temperature.

18. The method according to claim 14, further comprising:

prohibiting the disconnection irrespective of the temperature when an access request that requests activation of the word line conflicts with a refresh request.

19. A memory system comprising:

a CPU; and

a semiconductor memory device that disconnects a sense amplifier from a bit line in a data read operation based on an instruction from the CPU,

wherein the disconnection of the sense amplifier from the bit line is performed when the temperature in the semiconductor memory device is a first temperature, and the disconnection of the sense amplifier from the bit line is not performed when the temperature in the semiconductor memory device is a second temperature.

20. A memory system according to claim 19, wherein the semiconductor memory comprises:

a disconnection circuit that disconnects the sense amplifier from the bit line;

a temperature sensing circuit that senses the temperature; and

a disconnection control circuit that controls execution or prohibition of the disconnection by the disconnection circuit based on the temperature.