Patent ID: 6614681
Filing Date: 2003-09-02
Classification: G11C

Abstract:
A thin film magnetic memory device, comprising:a plurality of magnetic memory cells for storing data written by an applied magnetic field, each of said plurality of magnetic memory cells including a magnetic storage portion having one of a first electric resistance value and a second electric resistance value that is larger than said first electric resistance value, according to a level of said storage data, and a memory cell selection gate connected in series with said magnetic storage portion, and rendered conductive when selected; a first data line electrically coupled to said magnetic storage portion and said conductive memory cell selection gate of a selected magnetic memory cell and receiving a data read current in data read operation; a dummy memory cell having an intermediate electric resistance value of said first and second electric resistance values, said dummy memory cell including a dummy resistance portion having said first electric resistance value, and a dummy memory cell selection gate connected in series with said dummy resistance portion, and rendered conductive when selected; a second data line electrically coupled to said dummy resistance portion and said conductive dummy memory cell selection gate and receiving said data read current in said data read operation; and a data read circuit for producing read data base on a voltage change on said first and second data lines, wherein an electric resistance value of said conductive dummy memory cell selection gate is larger than a third electric resistance value and is smaller than a sum of a different between said second and first electric resistance values and said third electric resistance value, said third electric resistance value being an electric resistance value of said conductive memory cell selection gate.