US 5,969,572 AGranted

Linear power amplifier and method for canceling intermodulation distortion signals

AssigneeSamsung Electronics Co., Ltd.

InventorsYong-Chae Jeong, Young Kim, Ik-Soo Chang

Life of this patent

Estimating the term…

Loading patent…

Abstract

A feedforward-type linear power amplifier directly compares amplitude and phase of a signal applied to one input end of a first signal canceler with amplitude and phase of a signal applied to another input end of the first signal canceler, and according to the comparison results, controls a first variable attenuator and a first variable phase shifter disposed in a pre-stage of the first signal canceler so that the first signal canceler extracts only the intermodulation distortion signals generated while a main power amplifier amplifies the RF input signal. Then, the linear power amplifier directly compares amplitude and phase of the intermodulation distortion signal on a main path with amplitude and phase of the intermodulation distortion signal on a sub path, and according thereto, controls a third variable attenuator and a third variable phase shifter to cancel the intermodulation distortion signals contained in the RF output signal of the main power amplifier.

Claims12

Dependent claims

A feedforward-type linear power amplifier including a power amplifier for amplifying an RF (Radio Frequency) input signal, comprising:

a first attenuation/phase controller for comparing amplitude and phase of the amplified signal with amplitude and phase of the RF input signal to control the amplitude and phase of the RF input signal;
a first signal canceler for canceling the signal whose amplitude and phase are controlled by said first attenuation/phase controller, from said amplified signal, so as to extract intermodulation distortion signals from said amplified signal;
a second attenuation/phase controller for comparing amplitude and phase of the amplified signal with amplitude and phase of the RF input signal, to control the amplitude and phase of the RF input signal, said amplified signal and said RF input signal being delayed respectively by first and second delay lines;
a second signal canceler for canceling the signal whose amplitude and phase are controlled by said second attenuation/phase controller, from said amplified delay signal, so as to extract intermodulation distortion signals from said amplified delay signal;
a third attenuation/phase controller for comparing amplitude and phase of an output signal of said second signal canceler with amplitude and phase of an output signal of an error amplifier, to control the amplitude and phase of the extracted intermodulation distortion signal;
and
a device including said error amplifier, for amplifying the intermodulation distortion signal whose amplitude and phase are controlled by said third attenuation/phase controller, and combining the amplified intermodulation distortion signal with said amplified signal to cancel the intermodulation distortion signals included in said amplified signal.

4 more elements

A method for canceling an intermodulation distortion signal in a feedforward-type linear power amplifier including a power amplifier for amplifying an RF input signal, comprising the steps of:

(a) comparing amplitude and phase of the amplified signal with amplitude and phase of the RF input signal to control the amplitude and phase of the RF input signal;
(b) canceling the signal whose amplitude and phase are controlled in said step (a), from said amplified signal, so as to extract intermodulation distortion signals from said amplified signal;
(c) comparing amplitude and phase of the amplified signal with amplitude and phase of the RF input signal to control the amplitude and phase of the RF input signal, said amplified signal and said RF input signal being delayed respectively by first and second delay lines;
(d) canceling the signal whose amplitude and phase are controlled in said step (c), from said amplified delay signal, so as to extract intermodulation distortion signals from said amplified delay signal;
(e) comparing amplitude and phase of said intermodulation distortion signals extracted in said step (d) with amplitude and phase of an output signal of an error amplifier, to control the amplitude and phase of the extracted intermodulation distortion signals;
and
(f) amplifying the intermodulation distortion signal whose amplitude and phase are controlled in said step (e) and combining the amplified intermodulation distortion signal with said amplified signal to cancel the intermodulation distortion signals included in said amplified signal.

4 more elements

Dependencies are inferred from the claim text.