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Semiconductor memory

A memory and semiconductor technology, applied in static memory, digital memory information, information storage, etc., can solve problems such as power consumption and battery consumption

Inactive Publication Date: 2009-01-14
SOCIONEXT INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, a handheld terminal using DRAM as its work memory consumes power just to hold data even when it is not in use, so that the battery is consumed

Method used

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  • Semiconductor memory
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Experimental program
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Embodiment Construction

[0070] Embodiments of the present invention will be described below using the drawings. In the drawings, each signal line shown by a thick line indicates that it is composed of a plurality of lines, and each block connected by a signal line of a thick line is composed of a plurality of circuits. Each signal ending with a "Z" represents positive logic, and each signal beginning with a " / " or ending with an "X" represents negative logic. Double circles in the drawings represent external terminals. The signal lines are designated by the same reference symbols as those designating the names of signals transmitted therethrough. In the following description, signal names are sometimes abbreviated, for example, "clock signal CLK" is written as "CLK signal", and "chip enable signal CE" is written as "CE signal".

[0071] FIG. 1 shows a first embodiment of the semiconductor memory of the present invention. Using CMOS technology, the semiconductor memory is formed as a pseudo-SRAM wi...

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Abstract

A plurality of flags are formed so as to correspond to respective memory cell groups, each consisting of a plurality of volatile memory cells. Each flag indicates that the memory cell contains data in a second storage mode. When the first storage mode in which each memory cell holds data is switched to the second storage mode in which memory cells of each memory cell group holds the same data, each flag is reset in response to the first access of the corresponding memory cell group. For this, in each memory cell group, only the first access is performed in the second storage mode. In the aforementioned switching operation, by accessing a memory cell by the mode in accordance with the flag, a system managing the semiconductor memory can freely access the memory cell even during the switching operation. As a result, it is possible to substantially eliminate the switching time.

Description

technical field [0001] The present invention relates to semiconductor memories that require refresh operations to retain data written to memory cells. Background technique [0002] The memory capacity required for handheld terminals such as cellular phones is increasing year by year. Under such circumstances, dynamic RAM (hereinafter referred to as DRAM) has started to be used as a work memory of the handheld terminal instead of conventional static RAM (hereinafter referred to as SRAM). Since the number of elements constituting the memory unit of DRAM is less than that of SRAM, its chip size can be made smaller than that of SRAM, and its chip cost can be lower than that of SRAM. [0003] At the same time, the power consumption of semiconductor memories mounted on cellular phones must be low in order to allow long battery life. Unlike SRAM, DRAM requires periodic refresh operations in order to maintain the data written into its memory cells. Therefore, a handheld terminal ...

Claims

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Application Information

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IPC IPC(8): G11C11/4063G11C7/10G11C11/406
CPCG11C11/40615G11C2211/4067G11C11/406G11C11/40622G11C7/1045
Inventor 松崎康郎
Owner SOCIONEXT INC