Patent ID: 7282990

Claim:
An operational amplifier comprising: a differential amplifier for differentially amplifying first and second differential input signals to generate first and second output signals through first and second nodes; a driver for driving an output node in response to the second output signal; and a drive current adjuster for adjusting a driving current of the driver in response to the first output signal, wherein the drive current adjuster comprises: a first transistor including a drain connected to the output node, a gate, and a source connected to a ground voltage; a second transistor including a gate connected to the first node, a drain, and a source connected to a source voltage; a third transistor including a drain connected to the drain of the second transistor, a source, and a gate connected to a first bias voltage; and a fourth transistor including a drain connected to the source of the third transistor, a source connected to the ground voltage, and a gate connected to a second bias voltage, wherein the gate of the first transistor is commonly connected to the drains of the second and third transistors.