Efficient class-G amplifier with wide output voltage swing
First Claim
1. An amplifier, comprising:
- an input stage configured to receive an amplifier input signal;
a plurality of output stages configured to combinatorially produce an amplifier output; and
an output stage controller coupled to the input stage and the output stages;
wherein each of the plurality of output stages is configured to receive a supply voltage that is different from any other output stage;
wherein each of the plurality of output stages comprises an output transistor; and
wherein in response to the amplifier input signal, the output stage controller is configured to generate control signals that cause each of the plurality of output stages to contribute current to the output of the amplifier when the output of the amplifier is less than the supply voltage received by the output stage.
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Abstract
Various embodiments of methods and apparatus for an amplifier with wide output voltage swing are disclosed. The amplifier may include multiple output stages, each associated with a distinct supply voltage. Each output stage may contribute current to the output of the amplifier over a range of amplifier output voltages and these ranges may overlap. Each output stage may contribute current until the amplifier output voltage reaches the supply voltage associated with that output stage. The amplifier output may be as great as the largest supply voltage minus a drop equal to Rdson for an output transistor multiplied by the output current. In a CMOS implementation, this voltage drop may be approximately 0.15V. When the amplifier output voltage is close to the supply voltage associated with an output stage, both that output stage and the output stage associated with the next highest supply voltage may contribute to the amplifier output.
128 Citations
32 Claims
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1. An amplifier, comprising:
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an input stage configured to receive an amplifier input signal;
a plurality of output stages configured to combinatorially produce an amplifier output; and
an output stage controller coupled to the input stage and the output stages;
wherein each of the plurality of output stages is configured to receive a supply voltage that is different from any other output stage;
wherein each of the plurality of output stages comprises an output transistor; and
wherein in response to the amplifier input signal, the output stage controller is configured to generate control signals that cause each of the plurality of output stages to contribute current to the output of the amplifier when the output of the amplifier is less than the supply voltage received by the output stage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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- 13. A class G amplifier, wherein when the amplifier output voltage is in a range between the supply voltage received by an output stage and a voltage differential, delta V, below said supply voltage, both that output stage and another output stage receiving a next higher supply voltage contribute current to the amplifier output.
- 17. A class G amplifier, wherein each of the plurality of output stages, except for an output stage configured to receive a lowest supply voltage, is configured to contribute current to the amplifier output when the amplifier output voltage is in a range from the supply voltage received by that output stage to a next lower supply voltage less a differential voltage, delta V.
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21. A method comprising:
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outputting current from an output stage associated with a lowest supply voltage when an amplifier output voltage is less than the lowest supply voltage;
outputting current from an output stage associated with a highest supply voltage when the amplifier output voltage is greater than the next lower supply voltage minus delta V; and
outputting current from an output stage associated with a supply voltage other than the lowest or highest supply voltage when the amplifier output voltage is between a next lower supply voltage minus delta V, and the supply voltage associated with that output stage. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. A method comprising:
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generating a first current that is inversely proportional to an output voltage of an amplifier;
generating a second current that is directly proportional to a sum of currents output by the output stages of the amplifier;
combining the first and second currents such that under normal amplifier operation the resulting current is constant and less than a limiting value, Ilim, for a range of output voltages for the amplifier. - View Dependent Claims (30, 31, 32)
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Specification