Method and apparatus for feedforward power amplifying
AssigneeMotorola, Inc.
InventorJames E. Mitzlaff
Life of this patent
Estimating the term…
Abstract
A feedforward distortion minimization circuit includes a first loop with an input splitter and first and second signal paths, each signal path having an amplifier. An output combiner couples the two signal paths and has an output signal path and an output dump load path. A first signal detector on the dump load path detects a dump load signal, and in response a gain and phase controller operates to adjust the gain and phase of a first signal on one of two signal paths to minimize the power delivered to the dump load. The feedforward circuit also includes embodiments in which both amplifiers operate at around the same power amplification level, and in which a second loop has an error amplifier for further distortion correction.
Claims29
A method of minimizing distortion produced by a power amplifier, comprising:
- (a) receiving an input signal;
- (b) providing a first loop having an input for receiving the input signal, a first signal path and a second signal path;
- (c) on the first signal path, generating a first amplified output signal having a distortion component by a first amplifier responsive to the input signal;
- (d) on the second signal path, generating a second amplified output signal having a distortion component by a second amplifier responsive to at least the input signal;
- (e) coupling the first and second signal paths via a first combiner so as to combine the first and second amplified output signals into a distortion corrected first loop output signal and a dump load signal;
- and
- (f) detecting the dump load signal and adjusting amplitude and phase of signals on at least one of the first and second signal paths in response to the detected dump load signal.
A method of linearly amplifying a signal, comprising:
- (a) receiving an input signal;
- (b) providing a first loop having an input for receiving the input signal, a first signal path and a second signal path;
- (c) on the first signal path, generating a first amplified output signal having a first amplitude and a distortion component by a first amplifier responsive to the input signal;
- (d) on the second signal path, generating a second amplified output signal having a second amplitude of approximately the same order of magnitude as the first amplitude and a distortion component by a second amplifier responsive to at least the input signal;
- (e) coupling the first and second signal paths via a combiner so as to combine the first and second amplified output signals and output a distortion corrected first loop output and a dump load signal;
- and
- (f) detecting at the combiner the dump load signal and adjusting amplitude and phase of signals on at least one of the first and second signal paths in response to the detected dump load signal.
A method of aligning a first loop of a linear amplifier, the first loop having a first loop input for receiving an input signal, first and second signal paths having first and second amplifiers, respectively, and a first combiner coupling the first and second signal paths, after the first and second amplifiers, so as to output a distortion corrected first loop output signal, comprising:
- (a) providing a second combiner coupling the first and second signal paths prior to the second amplifier, a first gain and phase control coupled between the second combiner and the second amplifier, and a second gain and phase control coupled after the first loop input on one of the first and second signal paths;
- (b) receiving an input signal at the first loop input;
- (c) on the first signal path, generating a first amplified output signal having a first amplitude and a distortion component by the first amplifier responsive to the input signal, and injecting a pilot tone;
- (d) on the second signal path, generating a second amplified output signal having a second amplitude of approximately the same order of magnitude as the first amplitude and a distortion component by the second amplifier responsive to at least the input signal;
- (e) detecting the distortion corrected first loop output, including a pilot tone component from the injected pilot tone signal;
- (f) adjusting the first gain and phase control so as to minimize the detected pilot tone component;
- and
- (g) next adjusting the second gain and phase control so as to maximize power of the detected distortion corrected first loop output.
A method of minimizing distortion produced by a power amplifier having a first loop, the first loop having first and second signal paths each having an amplifier and an output combiner coupling the first and second signal paths, the output combiner having an output signal path and an output dump load path, the method comprising the steps of:
- (a) providing a signal detector on the dump load path and detecting a dump load signal;
- and
- (b) adjusting gain and phase of a first signal on at least one of the first and second signal paths in response to the detected dump load signal.
A feedforward distortion minimization circuit comprising:
- a first loop having a first input splitter and first and second signal paths from the output of the first splitter, each signal path having an amplifier;
- an output combiner coupling the first and second signal paths, the output combiner having an output signal path and an output dump load path;
- a first signal detector on the dump load path operable for detecting a dump load signal;
- and
- a gain and phase controller being operable for adjusting gain and phase of a first signal on at least one of the first and second signal paths in response to the detected dump load signal.
A feedforward power amplifier having a first loop, the first loop having first and second signal paths each having an amplifier, comprising:
- an output combiner means for coupling the signal paths, having an output signal path and an output dump load path;
- signal detector means, on the dump load path, for detecting a dump load signal;
- and
- control means for adjusting gain and phase of a first signal on at least one of the signal paths in response to the detected dump load signal.
Dependencies are inferred from the claim text.