Patent ID: 7855600

Claim:
An operational amplifier comprising: a first current mirror connected between a first power source and a first control node and including a reference current branch and a mirror current branch; a second current mirror connected between a second power source and a second control node; a first transistor connected between the first power source and an output node and turned on/off in response to a voltage of the first control node; a second transistor connected between the output node and the second power source and turned on/off in response to a voltage of the second control node; a transistor pair connected to the second power source through a current source and including a third transistor having a drain connected to the reference current branch and a fourth transistor having a drain connected to the mirror current branch; a bias circuit connected between the first control node and a second control node for biasing the first transistor and comprising a first pair of transistors being responsive to a first bias control voltage and for biasing the second transistor and comprising a second pair of transistors being responsive to a second bias control voltage; and a capacitor connected between the mirror current branch and the output node.