Patent ID: 6617924
Filing Date: 2003-09-09
Classification: H03F

Abstract:
An operational amplifier comprising:a shift section for generating two shifted signals by shifting two input signals by a predetermined voltage; a differential input section for generating a first signal corresponding to a differential voltage between the two shifted signals; an amplifying section for amplifying the first signal in voltage to generate a second signal; a first MOS transistor connected between a first supply voltage and an output node, a conduction state of the first MOS transistor being controlled according to the second signal; a second MOS transistor connected between a second supply voltage and the output node, a conduction state of the second MOS transistor being controlled in accordance with the first signal; and a step-up section to which the first and second supply voltages are applied to generate a step-up voltage that is higher than the first supply voltage; wherein the first and second transistors have channels of the same conductivity type, and wherein the amplifying section is driven by the step-up voltage so that the absolute value of the maximum level of the second signal becomes larger than the absolute value of the difference between the first and second supply voltages.