Patent ID: 8487690

Claim:
A dual mode charge pump operable in a first mode and a second mode, comprising: a power input terminal receiving an input voltage; a ground terminal as a relative zero for voltage calculation; a first voltage output terminal and a second voltage output terminal; a flying capacitor having a first terminal and a second terminal; and a switch capacitor network connected to the power input terminal, the ground terminal, the first and second terminals of the flying capacitor, and the first and second voltage output terminals; wherein in the first mode a first positive voltage and a first negative voltage of a same first absolute value are generated at the first and second voltage output terminals, respectively, the first absolute value is adjustable even if the input voltage is constant, and the first absolute value is smaller than or equal to a voltage between the first and second terminals of the flying capacitor, and in the second mode a second positive voltage and a second negative voltage of a same second absolute value are generated at the first and second voltage output terminals, respectively, the second absolute value is adjustable even if the input voltage is constant, and the second absolute value is smaller than or equal to a half of the voltage between the first and second terminals of the flying capacitor.