A semiconductor memory device includes a memory cell including a memory magnetic tunnel junction (MTJ) configured to be coupled to a first sensing node and a reference cell including a first resistance element and a second resistance element configured to be coupled in parallel to a second sensing node, the first resistance element including a first number of reference MTJs and the second resistance element including a second number of reference MTJs different from the first number of reference MTJs. The memory device further includes a sensing circuit configured to be coupled to the first and second sensing nodes and to detect a difference in resistance between the memory cell and the reference cell. In some embodiments, the first number of reference MTJs includes first reference MTJs connected in series and the second number of reference MTJs includes second reference MTJs connected in series.