Patent ID: 7132859

Claim:
A common-mode current feedback amplifier circuit, comprising: a first input buffer ( 406 a ) having an input ( 402 a ) forming a first non-inverting input (IN+A) of the amplifier circuit, and an output ( 404 a ) forming a first inverting input (IN−A) of the amplifier circuit, the first input buffer ( 406 a ) producing a first current (½ IA), a second current (½ IA), a third current (−½ IA), and a fourth current (−½ IA); a second input buffer ( 406 b) having an input ( 402 b) forming a second non-inverting input (IN+B) of the amplifier circuit, and an output ( 404 b ) forming a second inverting input (IN−B) of the amplifier circuit, the second input buffer ( 406 b ) producing a fifth current (½ IB), a sixth current (½ IB), a seventh current (−½ IB), and an eighth current (−½ IB); a first current mirror ( 410 a ) receiving the first and the sixth currents, and providing a current proportional to a sum of the first and the sixth currents (½ (IA+B)) to a first high impedance node ( 414 a ); a second current mirror ( 412 a ) receiving the third and the eighth currents, and providing a current proportional to a sum of the third and eighth currents (−½ (IA+IB)) to the first high impedance node ( 414 a ); a third current mirror ( 410 b ) receiving the fifth and the second currents, and providing a current proportional to a sum of the fifth and second currents (½ (IB+IA)) to a second high impedance node ( 414 b ); a fourth current mirror ( 412 b ) receiving the seventh and the fourth currents, and providing a current proportional to a sum of the seventh and fourth currents (−½(IB+IA)) to the second high impedance node ( 414 b ); and a first output buffer ( 408 a ) having an input and an output ( 416 a ), the input connected to the first high impedance node ( 414 a ), and the output ( 416 a ) forming a first output (OUTA) of the amplifier circuit; and a second output buffer ( 408 b ) having an input and an output ( 416 b ), the input connected to the second high impedance node ( 414 b ), and the output ( 416 b ) forming a second output (OUTB) of the amplifier circuit.