Operational amplifier having large output current with low supply voltage

An operational amplifier comprising:

• a shift section that generates two shifted signals by shifting two input signals by a predetermined voltage;
• a differential input section that generates a first signal corresponding to a differential voltage between the two shifted signals;
• an amplifying section that amplifies the first signal in voltage to generate a second signal;
• an output section that generates an output signal at an output node responsive to the first and second signals;
• and
• a step-up section that generates a step-up voltage responsive to first and second supply voltages, the step-up voltage driving the amplifying section and being greater than the first supply voltage, the step-up section comprising:
• a plurality of first MOS transistors connected in series between the first supply voltage and a first node,
• a plurality of first capacitors having first and second ends, the first ends of the plurality of first capacitors being coupled to respective nodes located between the plurality of first MOS transistors and the second ends being coupled to clock signals,
• a plurality of second MOS transistors connected in series between the first node and the second supply voltage, and
• a storage capacitor connected between the first node and the second supply voltage,
• the step-up voltage being output from the first node.