Memory cell condition evaluation device for magnetoresistive memory

摘要

The evaluation device uses a pair of reference resistances (RR1,RR2) associated with the cell resistance (R) and simultaneously connected to the word line voltage (Vwl). The reference cell resistances cooperate with a feedback amplifier (OP2,RG2) to provide a summation amplifier and the cell resistance cooperates with a second feedback amplifier (OP1,RG1) to provide an amplifier with the same amplification as the summation amplifier. The outputs of the summation amplifier and the amplifier are fed to a comparator, providing a voltage difference signal (Vout) dependent on the cell resistance.