Power amplifier (PA) with improved power regulation
First Claim
1. A circuit for amplifying an input signal, comprising:
- a power amplifier that receives the input signal and produces an output signal;
an amplitude detector coupled to an output of the power amplifier that produces a first measurement that corresponds to the amplitude of the output signal;
a power source for providing power to the power amplifier;
a current detector that produces a second measurement that corresponds to the current flowing into the power amplifier from the power source;
an adder for adding the first measurement with the second measurement to produce a third measurement; and
a control circuit connected to a biasing pin of the power amplifier for comparing the third measurement to a reference and for controlling the output power of the power amplifier based on the comparison.
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Accused Products
Abstract
A circuit for regulating the power provided to a load connected to an output of a power amplifier. The circuit includes an amplitude detector that outputs a voltage corresponding to the amplitude of the signal outputted by the power amplifier. This output voltage is a function of the impedance of the load. Thus, when the impedance of the load changes, the output voltage also changes. Given a constant current into the load, it is the load impedance that determines the power delivered to the load. Therefore, because the output voltage reflects changes in the impedance of the load, the output voltage can be used by a regulator circuit to maintain a constant output power, regardless of changes in the impedance of the load.
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Citations
17 Claims
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1. A circuit for amplifying an input signal, comprising:
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a power amplifier that receives the input signal and produces an output signal;
an amplitude detector coupled to an output of the power amplifier that produces a first measurement that corresponds to the amplitude of the output signal;
a power source for providing power to the power amplifier;
a current detector that produces a second measurement that corresponds to the current flowing into the power amplifier from the power source;
an adder for adding the first measurement with the second measurement to produce a third measurement; and
a control circuit connected to a biasing pin of the power amplifier for comparing the third measurement to a reference and for controlling the output power of the power amplifier based on the comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit for amplifying an input signal, comprising:
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a power amplifier that receives the input signal and produces an output signal;
an amplitude detector means, coupled to an output of the power amplifier, for producing a first measurement that corresponds to the amplitude of the output signal;
a means for providing power to the power amplifier;
a current detector means for producing a second measurement that corresponds to a current flowing into the power amplifier from the power providing means;
an adding means for adding the first measurement with the second measurement to produce a third measurement; and
a control circuit means, connected to a biasing pin of the power amplifier, for comparing the third measurement to a reference and for controlling the output power of the power amplifier based on the comparison. - View Dependent Claims (9, 10, 11, 12, 13, 14, 16, 17)
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15. A method, comprising the steps of:
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producing a first measurement corresponding to the amount of current flowing into a power amplifier from a power source;
producing a second measurement corresponding to the amplitude of an output signal produced by the power amplifier;
adding the first measurement to the second measurement to produce a sum;
comparing the sum to a reference;
controlling the power amplifier based on a result of the comparison.
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Specification