Apparatus and methods for power amplifier bias circuits
First Claim
1. A power amplifier system comprising:
- a power amplifier stage configured to receive a bias voltage that biases the power amplifier stage;
a current source configured to generate a reference current;
a plurality of reference bipolar transistors;
a selection circuit configured to select one or more selected reference bipolar transistors from the plurality of reference bipolar transistors, the one or more selected reference bipolar transistors having a current therethrough that changes in relation to the bias voltage; and
a transimpedance amplifier configured to control the bias voltage based on an error current corresponding to a difference between the reference current and the current through the one or more selected reference bipolar transistors.
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Abstract
Apparatus and methods for power amplifier bias circuits are disclosed herein. In certain implementations, a power amplifier bias circuit includes a current source configured to generate a reference current, a plurality of reference bipolar transistors, a selection circuit configured to select one or more selected reference bipolar transistors from the plurality of reference bipolar transistors, and a transimpedance amplifier. The one or more selected reference bipolar transistors have a current therethrough that changes in relation to a power amplifier stage bias voltage, and the transimpedance amplifier is configured to control the power amplifier stage bias voltage based on an error current corresponding to a difference between the reference current and the current through the one or more selected reference bipolar transistors.
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Citations
20 Claims
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1. A power amplifier system comprising:
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a power amplifier stage configured to receive a bias voltage that biases the power amplifier stage; a current source configured to generate a reference current; a plurality of reference bipolar transistors; a selection circuit configured to select one or more selected reference bipolar transistors from the plurality of reference bipolar transistors, the one or more selected reference bipolar transistors having a current therethrough that changes in relation to the bias voltage; and a transimpedance amplifier configured to control the bias voltage based on an error current corresponding to a difference between the reference current and the current through the one or more selected reference bipolar transistors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of biasing a power amplifier, the method comprising:
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biasing a power amplifier stage using a bias voltage; generating a reference current using a current source; selecting one or more selected reference bipolar transistors from a plurality of reference bipolar transistors, the one or more selected reference bipolar transistors having a current therethrough that changes in relation to the bias voltage; generating an error current based on a difference between the reference current and the current through the one or more selected reference bipolar transistors; and controlling the bias voltage based on amplifying the error current using a transimpedance amplifier. - View Dependent Claims (13, 14, 15, 16)
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17. A bias circuit for biasing a power amplifier stage, the bias circuit comprising:
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a current source configured to generate a reference current; a plurality of reference bipolar transistors; a selection circuit configured to select one or more selected reference bipolar transistors from the plurality of reference bipolar transistors, the one or more selected reference bipolar transistors having a current therethrough that changes in relation to a power amplifier stage bias voltage; and a transimpedance amplifier configured to control the power amplifier stage bias voltage based on an error current corresponding to a difference between the reference current and the current through the one or more selected reference bipolar transistors. - View Dependent Claims (18, 19, 20)
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Specification