Low bias, high slew rate operational amplifier

Claim 1

An operational amplifier, comprising: an input differential amplifier stage including parallel inverting and non-inverting input transistors connected to an inverting input and non-inverting input, respectively; an output amplifier stage for generating an output signal; means connected to said input stage and to said output stage for providing a first signal to said output stage which is proportional to the difference between signals applied to the inverting and non-inverting inputs; complementary first and second sensing transistors connected in series, and connected to the inverting and non-inverting input transistors respectively, for receiving signals therefrom; a first current mirror transistor connected in series with said sensing transistors; and a second current mirror transistor connected in parallel with said first current mirror transistor and in series with said output stage, wherein current flowing through said second current mirror transistor flows into said output stage to provide a bias current thereto, and wherein the current flowing through said second current mirror transistor has the same magnitude as a current flowing through said first current mirror transistor; wherein the current flowing through said first current mirror transistor is controlled by the signals applied to said first and second sensing transistors.