A trimming process for setting a reference current used in operating an MRAM module comprising an operational MRAM cell coupled to a bit line, multiple reference MRAM cells coupled to a reference bit line, and a sense amplifier coupled to the bit line and the reference bit line is disclosed in some embodiments. The process includes applying a bit line reference voltage to the reference bit line to provide a reference cell current formed by a sum of respective currents through the plurality of reference MRAM cells. The reference cell current is detected. A determination is made as to whether the detected reference cell current differs from a target reference cell current. The bit line reference voltage is varied, or a sensing ratio of the sense amplifier is varied, if it is determined that the detected reference cell current differs from the target reference cell current.