Amplifier with extended output drive capability
AssigneeAT&T Bell Laboratories
InventorMadana K. N. Rao
Life of this patent
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Abstract
An operational amplifier is provided with at least one output supplementary stage and current mirror amplifiers for coupling amplified signal current variations to drive supplementary output stage source and sink transistors. Those transistors have their internal collector-emitter paths directly connected between supply rails and perform further amplification of the signals. A current source circuit is employed for so limiting those signal current variations that, after the further amplification, circuit devices will not be damaged.
Claims8
An amplifier having a first push-pull amplification output stage for controlling output current level in a first output current path therein between power supply rails and including an output terminal, said amplifier comprising
- means for mirroring current in said first output current path to produce a mirrored current,
- at least a second push-pull amplification output stage for controlling output current level in a second current path therein between said supply rails, said second current path including said output terminal, and
- means, responsive to said mirrored current, for current biasing said second amplification stage to produce further amplified current in said second current path and said output terminal.
Dependencies are inferred from the claim text.