Distributed RF power amplifier with load compensation
AssigneeMotorola, Inc.
InventorsRobert E. Stengel, Scott A. Olson
Life of this patent
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Abstract
A radio frequency power amplifier circuit according to certain embodiments of the present invention uses a distributed radio frequency amplifier 110 having a plurality of stages each with an input. The distributed radio frequency amplifier 110 drives an output load, such as an antenna 114. A drive signal synthesizer 106, having a plurality of outputs, drives the plurality of inputs to the distributed amplifier 110. Changes in load impedance are measured, e.g., using a directional coupler 160, and the measurement is used to change a drive signal produced by the drive signal synthesizer 106 to compensate for the change in load impedance.
Claims42
A radio frequency amplifier apparatus, comprising:
- a distributed radio frequency amplifier having a plurality of stages, the distributed radio frequency amplifier having an output stage that drives a load, the load having a load impedance;
- a drive signal synthesizer driving the plurality of amplifier stages;
- means for measuring a circuit parameter indicative of the load impedance;
- and
- means responsive to the measuring means for changing a drive signal produced by the drive signal synthesizer to compensate for the change in load impedance.
A radio frequency power amplifier apparatus, comprising:
- a distributed radio frequency amplifier having a plurality of N stages, the distributed radio frequency amplifier having an output at the Nth stage that drives a load, the load having a load impedance;
- a drive signal synthesizer driving the plurality of amplifier stages;
- a directional coupler coupling the Nth stage to the (N−1)th stage, and providing an coupler output for measuring a circuit parameter indicative of a change in the load impedance;
- and
- a programmed processor receiving the coupler output that computes a required change in drive signal to compensate for the change in load impedance, and which changes a drive signal produced by the drive signal synthesizer to compensate for the change in load impedance.
A radio frequency power amplifier apparatus, comprising:
- a distributed radio frequency amplifier having a plurality of stages each with an input, the distributed radio frequency amplifier having an output stage that drives a load, the load having a load impedance;
- a drive signal synthesizer driving the distributed amplifier;
- means for measuring a circuit parameter indicative of a change in the load impedance;
- and
- means responsive to the measuring means for changing a plurality of drive signals produced by the drive signal synthesizer to compensate for the change in load impedance.
A method of compensating for load impedance in an N stage distributed amplifier, comprising:
- measuring a circuit parameter indicative of a change in a load impedance;
- calculating a current required from a last stage of the distributed amplifier to make the load impedance appear to be a desired impedance;
- and
- applying an input to the last stage of the distributed amplifier to achieve the calculated current from the last stage of the distributed amplifier.
A method of compensating for an output load impedance in an N stage distributed amplifier, comprising:
- measuring a circuit parameter indicative of the output load impedance in the distributed amplifier;
- calculating one or more input signals to the N stage distributed amplifier to make a stage's load impedance appear to be a desired impedance;
- and
- applying the one or more calculated input signals to the N stage distributed amplifier to make the stage's load impedance for at least one of the stages from stage 1 to stage N be the desired impedance.
Dependencies are inferred from the claim text.