A semiconductor device includes a sense amplifier, a first magnetic tunneling junction (MTJ) connected to the sense amplifier at a first distance, a second MTJ connected to the sense amplifier at a second distance, and a third MTJ connected to the sense amplifier at a third distance. Preferably, the first distance is less than the second distance, the second distance is less than the third distance, a critical dimension of the first MTJ is less than a critical dimension of the second MTJ, and the critical dimension of the second MTJ is less than a critical dimension of the third MTJ.