Front end stage of an operational amplifier
AssigneeHarris Corporation
InventorGerald M. Cotreau
Life of this patent
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Abstract
The front end of an operational amplifier having an improved slew rate and high gain current output capabilities. The amplifier includes a slew enhancement or large signal stage connected in parallel to a normal front end or small signal stage. The small signal stage supplies a transconductance output which is approximately linearly related to the input until its slew rate limit. The slew enhancement stage is designed to provide slew current when the small signal stage reaches its slew rate limit, thereby providing an increased output current response to an increasing differential input voltage beyond the slew rate of the small signal stage.
Claims13
In an amplifier circuit having an input and an output stage, said circuit comprising:
- a small signal amplification means in said input stage for providing an output current in response to a differential input voltage;
- a large signal amplification means connected electrically in parallel in said input stage with said small signal amplification means for providing additional slew current only when the differential input voltage to the parallel circuit reaches a specified value;
- and
- summing means coupled between the outputs of said small signal amplification means and said large signal amplification means for providing a combined output current to said output stage for said amplifier circuit.
An amplifier circuit having an input and an output stage, said amplifier circuit comprising:
- a small signal amplification means in said input stage of said amplifier circuit for providing an output current as a function of a differential input voltage, up to a slew rate limit;
- a slew enhancement means connected in parallel in said input stage with said small signal amplification means, for providing additional slew output current when said amplification means reaches its slew rate limit;
- and
- summing means coupled between the outputs of said small signal amplification means and said slew enhancement means for providing a current output to said output stage for said amplifier circuit.
Dependencies are inferred from the claim text.