Charge pump with improved light-load efficiency and control method thereof

A charge pump, comprising:

• an input node, configured to receive an input voltage;
• an output node, configured to provide an output voltage;
• two bridge arms, coupled in parallel between the input node and a reference ground, wherein each of the two bridge arms has two pairs of switches coupled in series through an output node, and wherein each of the two pairs of switches has two switches coupled in series through a common node of the corresponding bridge arm;
• two capacitors, wherein one of the two capacitors is connected between the two common nodes of one of the two bridge arms, and the other one of the two capacitors is connected between the two common nodes of the other one of the two bridge arms;
• and
• a control circuit, configured to provide a first control signal and a second control signal having opposite logic states to control each of the two pairs of switches of the charge pump to work complementarily, and configured to keep one of the two capacitors electrically coupled between the input node and the output node, and to keep the other one of the two capacitors electrically coupled between the output node and the reference ground.

A control method for a charge pump, wherein the charge pump comprises two bridge arms coupled in parallel between an input node which receives an input voltage and a reference ground, and two capacitors corresponding to the two bridge arms, each of the two bridge arms having two pairs of switches coupled in series through an output node to provide an output voltage, and each of the two pairs of switches having two switches coupled in series through a common node of the corresponding bridge arm, and wherein one of the two capacitors is connected between the two common nodes of one of the two bridge arms, and the other one of the two capacitors is connected between the two common nodes of the other one of the two bridge arms, the control method comprising:

• providing a mode signal by comparing an output voltage of the charge pump with a first threshold voltage and a second threshold voltage via a hysteretic comparison;
• flipping logic states of a first control signal and a second control signal in response to transiting from a first status to a second status of the mode signal, wherein the first control signal and the second control signal have opposite logic states to control each of the two pairs of switches of the charge pump to work complementarily;
• and
• maintaining the logic states of the first control signal and the second control signal in response to transiting from the second status to the first status of the mode signal.