Voltage dropping apparatus, voltage switching apparatus, and internal voltage supply apparatus using the same

A voltage dropping apparatus comprising:

• a voltage dropping unit comprising transistors of opposite polarities connected in series with one another and configured to
• receive an input voltage,
• output the input voltage in a first mode, and
• drop a level of the input voltage in a second mode by using a threshold voltage of one of the transistors;
• a voltage output unit connected to the voltage dropping unit, and configured to
• receive and output the input voltage in the first mode, and
• receive and output the dropped voltage in the second mode;
• and
• a control unit configured to
• receive a mode signal and control a mode change of the voltage dropping unit and the voltage output unit based on a value of the mode signal,
• wherein the transistors include n-type metal-oxide-semiconductor (NMOS) transistors of which source terminals and drain terminals are connected to each other in series and p-type metal-oxide-semiconductor (PMOS) transistors of which source terminals and drain terminals are connected to each other in series, and
• the voltage dropping unit receives a control signal from the control unit through a gate terminal of one of the NMOS transistors and drops the level of the input voltage by using a threshold voltage of one of the PMOS transistors.