Switching circuit and small-size high-efficiency DC-DC converter for portable devices including the same

A small-size high-efficient direct current-to-direct current (DC-DC) converter for portable devices, comprising:

• a switching circuit that generates a square wave, the switching circuit comprising:
• a normal mode operation unit that includes:
• first and second dynamic threshold-complementary metal oxide semiconductor (DT-CMOS) transistors each having a gate connected with a body thereof and having a threshold voltage that is reduced in a normal mode and restored in a standby mode, the first DT-CMOS transistor being of a first-type MOS and the second DT-CMOS transistor being of a second-type MOS, and
• diode-connected first and second MOS transistors configured to further reduce the threshold voltage of the first and second DT-CMOS transistors in the normal mode, the diode-connected first MOS transistor being of the first-type MOS transistor and connected between the gate and the body of the first DT-CMOS transistor, the diode-connected second MOS transistor being of the second-type MOS transistor and connected between the gate and the body of the second DT-CMOS transistor;
• and
• a standby mode operation unit that includes:
• third and fourth MOS transistors, the third MOS transistor being of the first-type MOS transistor and connecting the body of the first DT-CMOS transistor with a power supply terminal, the fourth MOS transistor being of the second-type MOS transistor and connecting the body of the second DT-CMOS transistor with a ground terminal;
• and
• first and second inverters, the first inverter coupled between the gate of the first DT-CMOS transistor and a gate of the third MOS transistor, the second inverter coupled between the gate of the second DT-CMOS transistor and a gate of the fourth MOS transistor;
• an inductor and a capacitor that filter the square wave generated by the switching circuit and output a DC voltage;
• and
• a pulse width modulator that generates a pulse width modulation signal that adjusts a level of the DC voltage and outputs the pulse width modulation signal to the switching circuit.