A memory device may include a data region, a reference region, a resistor circuit, and a sense amplifier. The data region may include a plurality of data memory cells coupled between a first bit line and a first source line. The data region may provide a data voltage corresponding to data stored in each of the data memory cells. The reference region may include a plurality of reference memory cells coupled between a reference bit line and a reference source line. The reference region may provide a reference voltage. The resistor circuit may include one or more resistors, and is coupled between the reference source line and a power source line. The sense amplifier may provide an output voltage by comparing the data voltage and the reference voltage. The power source line may be either a ground voltage or a negative voltage.