US Patent 7439803 Fully differential current-feedback CMOS/bipolar operational amplifier

A differential current amplifier circuit comprises a first low input impedance circuit that generates a first output current based on a first input current to the differential current amplifier circuit. A second low input impedance circuit generates a second output current based on a second input current to the differential current amplifier circuit. A first current subtraction circuit generates a first output voltage based on a difference between the first and the second output currents. A second current subtraction circuit generates a second output voltage based on a difference between the second and the first output currents.