Power amplifier with close-loop adaptive voltage supply
First Claim
1. An RF power amplifier system comprising:
- at least a first and a second power amplifier;
where a first RF signal is input to the first power amplifier that outputs a second RF signal, and wherein the second RF signal couples to the second power amplifier that outputs an RF output signal;
an RF power detector that receives the second RF signal and provides a linearly related DC voltage detect signal;
a DC to DC converter that receives the DC detect signal and outputs a corresponding supply voltage that is coupled to the second power amplifier, and wherein the second RF signal from the first power amplifier determines the optimum supply voltage for the second power amplifier, and the supply voltage determines the optimum output power from the second power amplifier; and
the DC voltage detect signal from the power detector is linearly related to the optimum supply voltage for the second power amplifier.
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Accused Products
Abstract
A two- (or multi) stage power amplifier receives a variable RF input signal, and outputs an optimized. RF output signal from, for example, a mobile handset. The output power level from the handset is predetermined, as known in the art, by the received control signal from a base station. The first power amplifier stage amplifies the variable RF input signal and outputs an RF signal, Vin, to a power detector circuit and an RF signal to the second or next amplifier stage. The power detect circuit amplifies the Vin signal and rectifies that signal with a linearly biased diode and provides a detect signal to a DC to DC converter. The converter responds by providing an optimum voltage bias, which is linearly related to the DC voltage detect signal from the power detector, to the output stage, and, if desired, to the first and/or other stages of the power amplifier that optimizes the output power level while meeting the required linearity specification. The battery current consumption is optimized through this automatic, dynamically control of the supply voltage for the power amplifier at each output power level through the DC to DC converter.
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Citations
10 Claims
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1. An RF power amplifier system comprising:
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at least a first and a second power amplifier;
where a first RF signal is input to the first power amplifier that outputs a second RF signal, and wherein the second RF signal couples to the second power amplifier that outputs an RF output signal;
an RF power detector that receives the second RF signal and provides a linearly related DC voltage detect signal;
a DC to DC converter that receives the DC detect signal and outputs a corresponding supply voltage that is coupled to the second power amplifier, and wherein the second RF signal from the first power amplifier determines the optimum supply voltage for the second power amplifier, and the supply voltage determines the optimum output power from the second power amplifier; and
the DC voltage detect signal from the power detector is linearly related to the optimum supply voltage for the second power amplifier. - View Dependent Claims (2, 3, 4, 5)
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6. A process for optimizing the RF output signal from an RF power amplifier system, the process comprising the steps of:
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receiving a first RF signal at a first power amplifier that outputs a second RF signal;
receiving the second RF signal at a second power amplifier, and wherein the second power amplifier outputs an RF output signal;
detecting the second RF signal and providing a DC voltage detect signal to a DC to DC converter;
generating a supply voltage from the DC to DC converter that is linearly related to the DC voltage detect signal; and
coupling the supply voltage to the second power amplifier, and wherein the supply voltage determines the optimum output power from the second power amplifier. - View Dependent Claims (7, 8, 9, 10)
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Specification