Patent ID: 7567454

Claim:
A thin film magnetic memory device, comprising: a plurality of memory cells for storing data, wherein each of said memory cells includes an access gate selectively turned ON in data read operation, and a magnetic storage portion connected in series with said access gate, and having either a first electric resistance or a second electric resistance higher than said first electric resistance depending on the stored data, and said thin film magnetic memory device further comprising: a data line that is electrically coupled to a selected memory cell through a turned-ON access gate of said selected memory cell in said data read operation, said selected memory cell being a memory cell selected from said plurality of memory cells for said data read operation; a reference data line for transmitting in said data read operation a read reference voltage for comparison with a voltage on said data line; and a plurality of dummy memory cells for producing said read reference voltage, wherein each of said dummy memory cells includes a dummy access gate selectively turned ON in said data read operation, a plurality of dummy magnetic storage portions that are electrically coupled to said reference data line in response to turning-ON of said dummy access gate, and a dummy resistance gate made of a field effect transistor, and wherein an electric resistance of said plurality of dummy magnetic storage portions is equal to said first electric resistance, and said dummy access gate in an ON state has an electric resistance that is equal to that of said access gate in an ON state, and said dummy resistance gate has a third electric resistance, said third electric resistance being smaller than a difference between said first and second electric resistance.