Phased array amplifier linearization
AssigneeAnalog Devices International Unlimited Company
InventorsAhmed I. Khalil, Patrick Pratt
Life of this patent
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Abstract
Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.
Claims20
An apparatus for radio frequency (RF) linearization of multiple amplifiers of a phased array, the apparatus comprising:
- a plurality of return paths configured to carry at least RF sample signals of a plurality of RF power amplifiers;
- a switch configured to electrically connect an antenna element to a transmit path in a first state and to electrically connect the antenna element to a return path of the return paths in a second state, wherein the switch is configured to leak a sufficient amount of power from the transmit path to the return path such that the return path receives enough transmit power represented in an RF sample of the RF sample signals for adaptive adjustment of predistortion, and wherein the switch is configured to leak the sufficient amount of power from the transmit path to a same point of the return path at which the switch electrically connects the antenna element to the return path in the second state;
- a hardware RF power combiner configured to combine the RF sample signals to generate a combined signal;
- a plurality of return-side phase shifters configured to adjust a phase shift of the RF sample signals such that the RF sample signals are phase aligned at the hardware RF power combiner;
- and
- a predistorter configured to predistort an input signal to generate a predistorted signal and configured to adapt predistortion coefficients for predistortion based at least partly on observations of a signal derived from the combined signal.
An apparatus for radio frequency (RF) linearization of multiple amplifiers of a phased array, the apparatus comprising:
- a plurality of return paths configured to carry at least RF sample signals of a plurality of RF power amplifiers, each return path of the plurality of return paths including a low-noise amplifier (LNA);
- means for providing RF samples to the plurality of return paths, the means for providing RF samples configured to leak a sufficient amount of power from a transmit path to a return path of the plurality of return paths, wherein the apparatus is configured to determine the sufficient amount of power based at least partially on an amount of gain of the LNA of the return path of the plurality of return paths;
- a hardware RF power combiner configured to combine the RF sample signals to generate a combined signal;
- a plurality of return-side phase shifters configured to adjust a phase shift of the RF sample signals such that the RF sample signals are phase aligned at the hardware RF power combiner;
- and
- a predistorter configured to predistort an input signal to generate a predistorted signal and configured to adapt predistortion coefficients for predistortion based at least partly on observations of a signal derived from the combined signal.
A method for radio frequency (RF) linearization of multiple amplifiers in a phased array, the method comprising:
- providing RF samples to respective return paths using switches, wherein a switch of the switches leaks a sufficient amount of power from a transmit path to a return path of the return paths such that the return path receives enough transmit power represented in an RF sample of the RF samples for adaptive adjustment of predistortion, wherein the switch leaks the sufficient amount of power from the transmit path to a same point of the return path at which the switch electrically connects an antenna element to the return path for receiving a signal from the antenna element;
- phase shifting the RF samples such that phase shifted RF samples are phase aligned at an RF power combiner;
- combining, with the RF power combiner, the phase shifted RF sample signals to generate a combined signal;
- and
- predistorting an input signal using predistortion coefficients to generate a predistorted signal, wherein the predistortion coefficients are based at least partly on observations of a signal derived from the combined signal.
Dependencies are inferred from the claim text.