Patent ID: 7233537

Claim:
A thin film magnetic memory device comprising: a plurality of memory cells each being configured to exhibit an electric resistance corresponding to a magnetization direction, and being magnetized in a direction corresponding to storage data; a dummy cell having a structure and a form similar to those of said memory cell, and being magnetized in advance in a direction corresponding to a predetermined level of said storage data; first and second data lines electrically coupled to a fixed voltage via one and the other of a selected memory cell among said plurality of memory cells and said dummy cell in a data read operation, respectively; a differential amplifier portion for reading out said storage data based on a comparison between electric resistances of said selected memory cell and said dummy cell, said differential amplifier portion including: a current supply circuit having first and second transistors electrically coupled between an operation voltage and first and second sense nodes, respectively, and each having a gate connected to one of first and second sense nodes, and a current amplifier circuit having third and fourth transistors electrically coupled between said first and second data lines and said first and second sense nodes, respectively; and a first offset adjusting circuit for applying first and second offset control voltages to gates of said third and fourth transistors, wherein said differential amplifier portion provides a first offset, when necessary, between passing currents of said first and second data lines such that the passing current of one of said first and second data lines electrically coupled to said dummy cell is set to a level intermediate between two kinds of passing currents respectively corresponding to levels of said storage data on the other of said first and second data lines electrically coupled to said selected memory cell.