Thin film magnetic memory device executing self-reference type data read
First Claim
1. A thin film magnetic memory device comprising:
- a plurality of memory cells each having an electric resistance according to a magnetic direction;
a data line electrically coupled to a fixed voltage through a selected memory cell selected as a data read target among said plurality of memory cells during data read;
a current supply circuit coupling said data line to a predetermined voltage for supplying a data read current to said selected memory cell at least during said data read;
a data write circuit applying a data write magnetic field to said selected memory cell; and
a data read circuit generating read data on the basis of stored data of said selected memory cell before and after application of said data write magnetic field, application of said data write magnetic field being executed at least once within one data read operation, wherein said data read circuit includes;
a voltage holding section holding a voltage of said data line applied by performing a read operation from said selected memory cell before the application of said data write magnetic field in an internal node; and
a voltage comparison section generating said read data in accordance with comparison between the voltage of said data line applied by performing the read operation from said selected memory cell after application of said data write magnetic field and a voltage of said internal node, and wherein, said read operation to said selected memory cell before the application of said data write magnetic field, said application of said data write magnetic field, and said read operation to said selected memory cell after the application of said data write magnetic field are continuously executed.
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Abstract
In one data read operation, data read for reading stored data before and after a predetermined data write magnetic field is applied to a selected memory cell, respectively, is executed, and the data read is executed in accordance with comparison of voltage levels corresponding to the data read operations before and after application of the predetermined data write magnetic field. In addition, data read operations before and after the application of a data write magnetic field are executed using read modify write. It is thereby possible to avoid an influence of an offset or the like resulting from manufacturing irregularities in respective circuits forming a data read path, to improve efficiency of the data read operation with accuracy and to execute a high rate data read operation.
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Citations
16 Claims
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1. A thin film magnetic memory device comprising:
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a plurality of memory cells each having an electric resistance according to a magnetic direction;
a data line electrically coupled to a fixed voltage through a selected memory cell selected as a data read target among said plurality of memory cells during data read;
a current supply circuit coupling said data line to a predetermined voltage for supplying a data read current to said selected memory cell at least during said data read;
a data write circuit applying a data write magnetic field to said selected memory cell; and
a data read circuit generating read data on the basis of stored data of said selected memory cell before and after application of said data write magnetic field, application of said data write magnetic field being executed at least once within one data read operation, wherein said data read circuit includes;
a voltage holding section holding a voltage of said data line applied by performing a read operation from said selected memory cell before the application of said data write magnetic field in an internal node; and
a voltage comparison section generating said read data in accordance with comparison between the voltage of said data line applied by performing the read operation from said selected memory cell after application of said data write magnetic field and a voltage of said internal node, and wherein, said read operation to said selected memory cell before the application of said data write magnetic field, said application of said data write magnetic field, and said read operation to said selected memory cell after the application of said data write magnetic field are continuously executed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A thin film magnetic memory device comprising:
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a plurality of memory cells arranged in a matrix, and each including a magneto-resistance element having an electric resistance according to a magnetic direction;
a plurality of source lines provided to correspond to rows of said memory cells, respectively; and
a plurality of bit lines provided to correspond to columns of said memory cells, respectively, wherein each of said memory cells is arranged between the corresponding source line and the corresponding bit line without using an access element, said thin film magnetic memory device further comprises;
a data line electrically coupled to the bit line corresponding to a selected memory cell selected as a data read target among said plurality of memory cells during data read;
a current supply circuit coupling the source line corresponding to said selected memory cell to a predetermined voltage and coupling the other source lines to a fixed voltage other than said predetermined voltage during said data read;
a data write circuit applying a data write magnetic field to said selected memory cell; and
a data read circuit generating read data on the basis of stored data of said selected memory cell before and after application of said data write magnetic field, application of said data write magnetic field being executed at least once within one data read operation, and said data read circuit includes;
a voltage holding section holding a voltage of said data line applied by performing a read operation from said selected memory cell before said data write magnetic field is applied, in an internal node; and
a voltage comparison section generating said read data in accordance with comparison between the voltage of said data line applied by performing the read operation from said selected memory cell after the application of said data write magnetic field, and a voltage of said internal node.
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9. A thin film magnetic memory device comprising:
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a plurality of memory cells arranged in a matrix, each memory cell, being magnetized along an easy axis in a direction according to magnetically written stored data, including a magneto-resistance element having an electric resistance according to a magnetic direction;
a plurality of source lines provided to correspond to rows of said memory cells, respectively; and
a plurality of bit lines provided to correspond to columns of said memory cells, respectively, wherein each of said memory cells is arranged between the corresponding source line and the corresponding bit line without using an access element, said thin film magnetic memory device further comprises;
a data line electrically coupled to the bit line corresponding to a selected memory cell selected as a data read target among said plurality of memory cells during data read;
a current supply circuit coupling the source line corresponding to said selected memory cell to a predetermined voltage and coupling the other source lines to a fixed voltage other than said predetermined voltage during said data read;
a bias magnetic field application section applying a bias magnetic field along a hard axis to said selected memory cell; and
a data read circuit generating read data according to stored data of said selected memory cell during said data read, on the basis of voltages of said data line before and after application of said bias magnetic field, respectively. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification