Patent ID: 7193448

Claim:
An operational amplifier comprising: a bias circuit arranged to provide a first voltage reference; an input stage including a differential amplifier, wherein the input stage is coupled to a pair of input terminals and is arranged to provide an output signal on a differential amplifier output; an output stage comprising first and second transistors and an output terminal, wherein only the second transistor of the first and second transistors is coupled to the differential amplifier output so as to directly receive the output signal, and wherein the output terminal is coupled between the first and second transistors; a feed forward amplifier coupled from the differential amplifier output and the bias circuit to the first transistor so as to extend the dynamic range of the operational amplifier, wherein the feed forward amplifier includes a current mirror that converts the first voltage reference to a current reference and back to a second voltage reference for supply to the output stage so that only the first transistor of the first and second transistors receives the second voltage reference; and an input bias cancellation circuit arranged to cancel base currents of at least one transistor within the input stage so as to track variations in Beta.