Patent ID: 7501894

Claim:
An operational amplifier comprising: a first transistor having a first current carrying electrode coupled to receive a first input voltage and source an output current to an output of the operational amplifier, the first transistor also having a second current carrying electrode and a control electrode; a second transistor having a first current carrying electrode coupled to receive a common voltage and sink an output current from an output of the operational amplifier, the second transistor also having a second current carrying electrode and a control electrode; a single differential pair having a third transistor coupled to receive a first input signal and a fourth transistor coupled to receive a second input signal, the third transistor having first and second current carrying electrodes and a control electrode, and the fourth transistor having first and second current carrying electrodes and a control electrode; a first current source coupled to provide a constant current through at least one of the third or fourth transistors of the differential pair, the first current source having a first terminal and a second terminal; and a control circuit coupled to the third transistor and the fourth transistor and configured to form a quiescent current through the first transistor and the second transistor that is ratioed to the constant current under the condition that substantially no load current flows through the first and second transistors and to form a maximum value of the output current that is not ratioed to the constant current.