Low bias current/temperature compensation current mirror for linear power amplifier
First Claim
Patent Images
1. A dynamic bias adjustor, comprising:
- a signal detector for determining the drive level of an amplifying device, and a bias output circuit connected to said signal detector and configured to operate the amplifying device in a Class B mode or substantially close to a Class B mode during low drive level conditions, and in a Class AB mode during high drive level conditions.
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Abstract
A power amplifier circuit whose performance is optimized by operating its stages in substantially close to a Class B mode by reducing quiescent current during low driver signal levels. As the driver signal amplitude increases, the operation of the amplifier is configured to dynamically adjust to be in a Class AB mode, thereby increasing the power efficiency of the overall circuit at kiw drive levels. A further enhancement to the power amplifier circuit includes a temperature compensation circuit to adjust the bias of the amplifier so as to stabilize the performance in a wide temperature range.
109 Citations
16 Claims
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1. A dynamic bias adjustor, comprising:
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a signal detector for determining the drive level of an amplifying device, and a bias output circuit connected to said signal detector and configured to operate the amplifying device in a Class B mode or substantially close to a Class B mode during low drive level conditions, and in a Class AB mode during high drive level conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of designing an efficiently biased amplifying circuit comprising a pre-amplifier stage, a driver stage and an output stage, the method comprising the steps of:
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providing a dynamic bias adjuster for detecting an alternating current voltage and generating a direct current output voltage having a value proportional to the alternating current voltage peak level;
connecting the dynamic bias adjuster to the driver output voltage; and
connecting the output voltage of the dynamic bias adjustor to bias the stages of the amplifying circuit whereby at least one of the stages of the amplifying circuit operates in a Class B mode or substantially close to a Class B when the driver output is at or below a predetermined level. - View Dependent Claims (10, 11)
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12. A method of implementing a biasing scheme for an amplifying device, comprising the steps of:
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monitoring a signal level at an output of the amplifying device;
producing a first signal proportional to the signal level; and
dynamically biasing, as a function of the first signal, the amplifying device to operate in a Class B mode or substantially close to a Class B mode when the signal level is low, and in a Class AB mode when the signal is high. - View Dependent Claims (13, 14, 15, 16)
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Specification