High performance class AB operational amplifier
AssigneesSTMicroelectronics (Grenoble 2) SAS, STMicroelectronics S.r.l.
InventorsMarcoOrazio Cavallaro, Serge Ramet, Tiziano Chiarillo
Life of this patent
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Abstract
A class AB operational amplifier includes an input stage, an output stage and a level shifter stage to control the quiescent current of the output stage and to transfer the signal from the input stage to the output stage, and a control circuit of the level shifter stage. The control circuit includes a transistor differential pair having a differential input terminals and the differential voltage at the differential terminals of the differential pair controls the level shifter stage.
Claims17
A class AB operational amplifier comprising:
- an input stage;
- an output stage;
- and
- a level shifter stage and a control circuit coupled thereto and configured to control a quiescent current of the output stage and to transfer a signal from the input stage to the output stage,
- the control circuit comprising
- a differential pair of transistors having differential input terminals,
- an impedance,
- first and second intermediate transistors coupled in series by the impedance and arranged between a first and a second reference voltage, and
- the impedance having a voltage thereacross being a differential voltage at the differential input terminals that controls the level shifter stage.
A class AB operational amplifier comprising:
- an input stage having a differential pair of transistors;
- an output stage;
- a level shifter stage to control the bias current of the output stage and to transfer the signal from the input stage to the output stage;
- and
- a control circuit coupled to the level shifter stage,
- wherein the control circuit comprises replica transistors from the level shifter stage and the output stage, and generates a replica output current from the output stage.
A class AB operational amplifier comprising:
- two symmetrical circuits, each circuit comprising:
- an input stage;
- an output stage;
- a level shifter stage to control the bias current of the output stage and to transfer the signal from the input stage to the output stage;
- an impedance;
- first and second intermediate transistors coupled in series by the impedance and arranged between a first and a second reference voltage;
- and
- a control circuit coupled to the level shifter stage,
- wherein the control circuit comprises replica transistors from the level shifter stage and the output stage, and generates a replica output current from the output stage.
Dependencies are inferred from the claim text.