Charge pump, a method for controlling the same, and a display driving system comprising the charge pump

A charge pump comprising:

• a first unit charge pump;
• and
• a second unit charge pump configured to receive an output voltage of the first unit charge pump as an input voltage, the first unit charge pump and second unit charge pump each including,
• a charge pumping unit configured to boost a first voltage in response to a clock signal, the first voltage being boosted to a second voltage having a voltage level higher than the first voltage by a middle voltage, the middle voltage being generated in response to a first control signal, the first control signal being enabled during a time period in which the clock signal and a second control signal are disabled and the charge pumping unit configured to boost the second voltage to a third voltage, the third voltage being a voltage level higher than an input voltage by the first voltage, the input voltage being generated in response to the second control signal;
• and
• a first transfer unit configured to output the third voltage in response to the second control signal.

A method of controlling a charge pump, the method comprising:

• boosting a first voltage in response to a clock signal to a second voltage having a voltage level higher than the first voltage by a middle voltage, the middle voltage being generated in response to a first control signal, the first control signal being enabled during a time period in which the clock signal and a second control signal are disabled;
• boosting the second voltage to a third voltage having a voltage level higher than an input voltage by the first voltage in response to a second control signal;
• and
• outputting the third voltage in response to the second control signal.