Class AB amplifier circuit
AssigneeSTMicroelectronics S.r.l.
InventorsMarius Reffay, Michel Barou
Life of this patent
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Abstract
A class AB amplifier circuit includes a complementary output stage and a biasing circuit for biasing the output stage. The complementary output stage includes a P-type MOS transistor and an N-type MOS transistor, and the biasing circuit includes a bipolar transistor. The emitter and collector of the bipolar transistor are respectively connected to the gates of the P-type and N-type MOS transistors. The bipolar transistor is biased for controlling a bias voltage between the respective gates of the P-type and N-type MOS transistors.
Claims30
A class AB amplifier circuit comprising:
- a complementary output stage comprising a P-type MOS transistor and an N-type MOS transistor connected in series between a first high-voltage reference and a low voltage reference, said P-type and N-type MOS transistors each having a gate;
- a bipolar transistor for controlling a bias voltage between the respective gates of said P-type and N-type MOS transistors;
- and
- bipolar transistor biasing means for biasing said bipolar transistor, and comprising
- a first resistor connected between a base and a collector of said bipolar transistor, and
- current means for causing a specific voltage drop across said first resistor.
A class AB amplifier circuit comprising:
- an output stage comprising a P-type MOS transistor and an N-type MOS transistor connected in series between a first high-voltage reference and a low voltage reference, said P-type and N-type MOS transistors each having a gate;
- a bipolar transistor for controlling a bias voltage between the respective gates of said P-type and N-type MOS transistors, said bipolar transistor having an emitter connected to the gate of said P-type MOS transistor and a collector connected to the gate of said N-type MOS transistor;
- and
- a bipolar transistor biasing circuit for biasing said bipolar transistor, and comprising
- a first resistor connected between a base and the collector of said bipolar transistor, and
- a current generating circuit for causing a specific voltage drop across said first resistor.
A method for biasing a complementary output stage of a class AB amplifier circuit, the complementary output stage comprising a P-type MOS transistor and an N-type MOS transistor connected in series between a first high-voltage reference and a low voltage reference, the method comprising:
- controlling a bias voltage between respective gates of the P-type and N-type MOS transistors using a bipolar transistor having an emitter connected to the gate of the P-type MOS transistor and a collector connected to the gate of the N-type MOS transistor;
- and
- biasing the bipolar transistor using a bipolar transistor biasing circuit comprising a first resistor connected between a base and the collector of the bipolar transistor, and a current generating circuit for causing a specific voltage drop across the first resistor.
Dependencies are inferred from the claim text.