The basic principle of MRAM

MRAM The difference from traditional ram is that MRAM The carrier of the information is a magnetic tunnel junction (MTJ ), The latter is the charge . Each magnetic tunnel junction consists of a fixed layer and a free layer . The magnetization direction of the fixed layer is fixed , The magnetization direction of the free layer can be changed by the rotating moment . When the magnetization directions of the two layers are the same , The magnetic tunnel junction has the lowest resistance , Its status is “0”; conversely , The magnetic tunnel junction has the highest resistance , Its status is “1”
 
Most commonly used MRAM The structure of the unit is made up of a NMOS Transistors and a MTJ( As a memory element ) form .MTJ And NMOS Sequential connection .NMOS Transistors are controlled by word line signals , When reading data ,NMOS Turn on , Add a small voltage difference between bit line and source line , To cause an electric current to flow through MTJ , Its size is determined by MTJ The state of... Determines . The readout amplifier compares this current with the reference current , Judge MRAM The data stored in the cell is “O” still “1”. When writing data , If write “O”, Then a larger positive voltage is added between the bit line and the source line ; If write “1”, Then add negative voltage . send MTJ The minimum current to flip is called the threshold current , And tunnel barrier material 、 Write the duration and MTJ The geometric structure of the . Traditional cache structure , from H-tree Connect , The number and size of rows and columns can be used CACTI Tools to optimize .