A memory array includes a plurality of columns of memory cells and each column of memory cells of the memory array is coupled to a local voltage source, a bit line, and a bit line bar. Provide a working voltage to pre-charge the bit line and the bit line bar of the column of memory cells when a memory cell of the column of memory cells is selected to be read, and meanwhile use local voltage sources coupled to remaining columns of memory cells of the memory array to provide high voltages lower than the working voltage to pre-charge bit lines and bit line bars of the remaining columns of memory cells.