Patent ID: 7894220

Claim:
A voltage generating circuit, comprising: a voltage output terminal and a ground terminal; a diode, having a first node connected to a voltage source and a second node; a capacitor, connected between a pump signal and the second node; a selector, controlled by a first control signal, used to select the voltage source or the voltage output terminal to connect to the second node, wherein the selector comprises: a second n-type metal-oxide-semiconductor (NMOS) transistor, wherein a gate of the second NMOS transistor is connected to the first control signal, a drain of the second NMOS transistor is connected to the voltage source, and a source of the second NMOS transistor is connected to the second node; and a first p-type metal-oxide-semiconductor (PMOS) transistor, wherein a gate of the first PMOS transistor is connected to the first control signal, a drain of the first PMOS transistor is connected to the voltage output terminal, and a source of the first PMOS transistor is connected to the second node; a first switch, controlled by a second control signal, wherein when the first switch is turned-on, the voltage output terminal is connected to the ground terminal; a second switch, controlled by a third control signal, wherein when the second switch is turned on, the voltage output terminal is connected to the voltage source; and a control unit used to generate the pump signal, the first, second and third control signals, wherein the first switch is turn-on after the second node is connected to the voltage source, and then the first switch is turn-off before the second node is connected to the voltage output terminal; wherein the pump signal is pulled down before the second node is connected to the voltage source; and wherein the second node is connected to the voltage output terminal before the pump signal is pulled up.