Unlock instant, AI-driven research and patent intelligence for your innovation.

Magnetic storage device

a magnetic storage and magnetic technology, applied in the field of magnetic storage devices, can solve the problems of increasing power consumption, large area, and increasing area

Inactive Publication Date: 2009-09-03
KK TOSHIBA
View PDF3 Cites 13 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a magnetic storage device with improved performance. The device includes a data transfer line, memory cells, a clamp transistor, a reading circuit, and a reference reading circuit. The reference reading circuit includes a reading node, a hold switch, a capacitor, a precharging switch, and an inverter. The device also includes a reference bit line and a reference clamp transistor. The technical effects of the invention include improved data transfer speed, reduced power consumption, and reduced noise.

Problems solved by technology

To realize this large resistance value, a large area is necessary, which is a problem in integration.
However, in the reading circuit of the capacity discharge system, a complicated voltage comparison circuit for detecting the signal and a latch circuit which holds the comparison result are necessary.
To constitute these circuits, a large number of transistors need to be used, which is a cause to bring about the increase of the area and the increase of power consumption.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Magnetic storage device
  • Magnetic storage device
  • Magnetic storage device

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0072]As shown in FIG. 1, a magneto-resistance random access memory (MRAM) cell 10 in which a resistance value changes in accordance with storage information is constituted by connecting a magnetic change type resistance element 11 referred to as a magnetic tunneling junction (MTJ) and a selection transistor 12 for cell selection in series. One end of the MTJ 11 (on a side opposite to the transistor 12) is connected to a bit line BL as a data transfer line. A gate terminal of the transistor 12 is connected to a word line WL for the cell selection, a drain end thereof is connected to the MTJ 11, and a source end thereof is connected to the ground. It is to be noted that, although not shown, the MRAM cells 10 are two-dimensionally arranged in a row direction and a column direction. Furthermore, the cells of the same row are connected to the same bit lines BL, and the cells of the same column are connected to the same word lines WL.

[0073]As shown in FIG. 2, a reading signal line RL for...

second embodiment

[0098]The reading circuit 30 for use in the first embodiment might be influenced by the fluctuation of a manufacturing process. In particular, when the fluctuation of the judgment voltage of the inverter 34 is generated, an MRAM process margin is largely influenced.

[0099]The process margin is critical for relieving the influence on the process fluctuation of the MRAM cell 10. A relation between the process fluctuation of the inverter 34 and the process margin will hereinafter be described with reference to FIGS. 8 and 9.

[0100]The inverter 34 is a 1-bit A / D converter which receives a voltage Vi to be held at a time when the hold switch 31 is turned off and which judges whether this voltage is not less than Vdd / 2 or not more than Vdd / 2, to determine an output. The judgment voltage of the inverter 34 is determined in accordance with the balance of the characteristics of pMOS and nMOS transistors constituting this circuit. The input / output characteristics shown by a solid line in FIG. 8...

third embodiment

[0116]A third embodiment of the present invention will be described with reference to FIG. 13.

[0117]On the same chip, a memory cell array portion 100 is arranged adjacent to a dummy cell array portion 200. In the memory cell array portion 100, a plurality of bit lines BL are arranged in a row direction. In the dummy cell array portion 200, one reference bit line BL′ is arranged along the row direction. A plurality of word lines WL are arranged to straddle the memory cell array portion 100 and the dummy cell array portion 200 in a column direction.

[0118]In the memory cell array portion 100, MRAM cells 101 are arranged in intersecting portions between the bit lines BL and the word lines WL, respectively. Each of the MRAM cells 101 is constituted by connecting a magnetic change type resistance element and a selection transistor in series as determined in the first embodiment. One end of the MRAM cell 101 is connected to the bit line BL, and a gate of the selection transistor is connect...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

A magnetic storage device includes a plurality of MRAM memory cells connected to a data transfer line, a clamp transistor connected between the data transfer line and a reading signal line and configured to fixedly hold the potential of the data transfer line, and a reading circuit which is connected to the reading signal line and which reads the storage information of the memory cell. The reading circuit includes a hold switch connected between the reading signal line and a reading node N and configured to hold the potential of the node N, a capacitor connected between the node N and a ground end, a precharging switch connected between the node N and a power source and configured to charge the capacitor, and an inverter to which the potential of the node N is input to generate a digital signal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2008-050566, filed Feb. 29, 2008, the entire contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a magnetic storage device in which a reading circuit for reading storage information from a memory cell formed using a magnetic material is improved.[0004]2. Description of the Related Art[0005]In recent years, much attention has been paid to a magnetic storage device using a magneto-resistance random access memory (MRAM) cell in which a resistance value changes in accordance with storage information.[0006]In a reading circuit which reads the signal of this type of MRAM cell, the output current of the MRAM cell is supplied to a resistor, and the output current is converted into a voltage. Then, this voltage value is compared with a refere...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): G11C11/02G11C7/00
CPCG11C7/02G11C11/15G11C7/14G11C7/067G11C11/1659G11C11/1673
Inventor FURUTA, MASANORIKUROSE, DAISUKESUGAWARA, TSUTOMU
Owner KK TOSHIBA