A typical conventional memory device includes a plurality of memory cells arranged in an array. Each of the memory cells can have a capacitor used as a storage node and a ferroelectric capacitor used as a memory unit for data storage. A control circuit can be used to access the memory cell, the access operation including two steps. The first step of accessing the memory cell is referred to as an act of reading data from the memory cell. The act of reading data from the memory cell includes two substeps. The first substep is to apply a voltage to the ferroelectric capacitor. The ferroelectric capacitor represents a memory unit having two stable polarization states, i.e., a data bit “1” or “0”. The polarization state of the ferroelectric capacitor is changed when the voltage is applied. The second substep is to detect the polarization state of the ferroelectric capacitor to obtain the information stored in the memory cell. The second step of accessing the memory cell is referred to as an act of writing data into the memory cell. The act of writing data into the memory cell includes two substeps. The first substep is to apply the voltage to the ferroelectric capacitor. The second substep is to apply a voltage higher than the first substep to the ferroelectric capacitor so as to change the polarization state of the ferroelectric capacitor, thereby, changing the polarization state of the ferroelectric capacitor from one stable polarization state to another stable polarization state. The change of the polarization state of the ferroelectric capacitor causes a loss of data stored in the memory cell. During the act of reading data from the memory cell, the polarization state of the ferroelectric capacitor is not necessarily changed, but may remain in one of the two stable polarization states. Therefore, during the act of reading data from the memory cell, the act of reading data from the memory cell is likely to generate an error in the data reading step. Furthermore, when reading data from a memory cell, a voltage higher than the normal operation voltage needs to be applied to the ferroelectric capacitor. Therefore, during the act of reading data from the memory cell, the reliability of reading data from the memory cell is degraded. Therefore, there is a need to provide an approach that can avoid the problem that the reliability of reading data from the memory cell is degraded when reading data from the memory cell. There is another need to provide an approach that can avoid the problem that the reliability of reading data from the memory cell is degraded when reading data from the memory cell. There is also another need to provide an approach that can avoid the problem that the reliability of reading data from the memory cell is degraded when reading data from the memory cell. There is also another need to provide an approach that can solve the problem that the reliability of reading data from the memory cell is degraded when reading data from the memory cell. Further, a ferroelectric capacitor is a capacitive device. It is a requirement of a ferroelectric capacitor in the conventional memory device that the voltage is applied only to the ferroelectric capacitor, so that the current consumption by the voltage applied to the ferroelectric capacitor is higher than the current consumption of an equivalent non-ferroelectric capacitor. Therefore, there is another need to provide a memory device having a ferroelectric capacitor for data storage that can save the current consumption of the voltage applied to the ferroelectric capacitor.