System for linear amplitude modulation
AssigneeQuintics Holdings
InventorsJohn Groe, Naone Farias, Burcin Baytekin, Carrie Lo
Life of this patent
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Abstract
System for linear amplitude modulation. Apparatus is provided for linear amplitude modulation of an amplifier. The apparatus includes a processing circuit that receives an amplitude modulation signal and produces one or more amplifier control signals that are coupled to the amplifier. The apparatus also includes a feedback circuit that generates a feedback signal from an output of the amplifier that is input to the processing circuit; and a network that controls a bias of the amplifier in response to the feedback signal to linearize the amplifier's amplitude control.
Claims42
Apparatus for linear amplitude modulation of a multi-stage amplifier, the apparatus comprising:
- a processing circuit that receives an amplitude modulation signal and a transmit control signal and produces at a first output a first amplifier control signal to control a first stage of the multi-stage amplifier and at a second output a second amplifier control signal to control a second stage of the multi-stage amplifier;
- a detector circuit coupled to the output of the multi-stage amplifier to generate, at an output, a signal representing the output of the multi-stage amplifier;
- a summing circuit having a first input coupled to the second output of the processing circuit to receive the second amplifier control signal and a second input coupled to the output of the detector circuit;
- and
- a network coupled to an output of the summing circuit to controls a bias or a gain signal of the multi-stage amplifier to linearize the amplifier's amplitude control.
A method for amplitude modulating a multi-stage amplifier, comprising:
- receiving, at a processing circuit, an amplitude modulation signal and a transmit control signal;
- providing a first output from the processing circuit to a first stage of the multi-stage amplifier to selectively amplitude modulate the first stage;
- providing a second output from the processing circuit to a summing circuit;
- combining, in the summing circuit, the second output with an output of a detector circuit coupled to an output of the multi-stage amplifier to generate a summing circuit output;
- and
- providing the summing circuit output to a network and the second stage to selectively amplitude modulate the second stage;
- wherein the first output signal is designated VGA* and the second amplifier control signal is designated PA*, with VGA* generated in accordance with a relationship governed by:
- VGA*=AM for AM<(P2−TX);
- VGA*=P2+u(PA*) for (P2−TX)>=AM<=(P1−TX);
- and
- VGA*=P2+u(Delta P2)+(AM−P1) for AM>(P1−TX);
- and
- wherein AM is a signal proportional to the amplitude modulation signal, P1 is a power level at which amplifier control through the bias network or voltage supply may be effected, P2 is the absolute lower limit of the amplifier's modulation range, u is a scaling factor, and TX is the transmit output power level set by the transmit control signal.
A method for amplitude modulating a multi-stage amplifier, comprising:
- receiving, at a processing circuit, an amplitude modulation signal and a transmit control signal;
- providing a first output from the processing circuit to a first stage of the multi-stage amplifier to selectively amplitude modulate the first stage;
- providing a second output from the processing circuit to a summing circuit;
- combining, in the summing circuit, the second output with an output of a detector circuit coupled to an output of the multi-stage amplifier to generate a summing circuit output;
- and
- providing the summing circuit output to a network and the second stage to selectively amplitude modulate the second stage;
- wherein the second output signal is designated PA*, with PA* generated in accordance with a relationship governed by:
- PA*=P2 for AM<(P2−TX)
- PA*=AM+TX for (P2−TX)>=AM<=(P1−TX);
- and
- PA*=P1 for AM>(P1−TX);
- and
- wherein AM is a signal proportional to the amplitude modulation signal, P1 is a power level at which amplifier control through the bias network or voltage supply may be effected, P2 is the absolute lower limit of the amplifier's modulation range, and TX is the transmit output power level set by the transmit control signal.
Dependencies are inferred from the claim text.