Patent ID: 8106863

Claim:
A common voltage generating circuit, comprising: a wave generating unit, a diode, a NOT gate, a first capacitor, a second capacitor, a third capacitor, a first resistor, a second resistor, and an output terminal; wherein the wave generating unit comprises an output terminal coupled to the output terminal of the common voltage generating circuit via the first resistor, a positive terminal of the diode, a negative terminal of the diode, and the second resistor in series; the output terminal of the wave generating unit is coupled to the negative terminal of the diode via the NOT gate and the first capacitor; the positive terminal of the diode is capable of being grounded via the second capacitor, and the output terminal of the common voltage generating circuit is grounded via the third capacitor; and wherein a wave signal is generated by the wave generating unit and configured to alternately switch on and switch off the diode, the first capacitor is directly charged by the wave signal via a cooperation of the diode and NOT gate, a duty ratio of the wave signal from the wave generating unit is capable of being modulated, and a charging time of the first capacitor is adjustable by modulating the duty ratio of the wave signal.