Circuit and method for compensating for non-linear distortion

• US 20020136324A1
• Filed: 03/20/2002
• Published: 09/26/2002
• Est. Priority Date: 03/22/2001
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Nagasaka, Hiroyuki
• Granted Patent: US 6,836,646 B2
• Time in Patent Office: Days
• US Class Current: 375/296
• CPC Class Codes: H03F 1/3294 Acting on the real and imaginary components of the input signal
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

An apparatus for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter for non-linearly high-power amplifying a baseband signal by a high-power amplifier after quadrature modulation having a distortion extractor for extracting a non-linear distortion component from the nonlinearly high-power amplified modulated signal. A quadrature modulator quadrature-modulates the non-linear distortion component into a baseband distortion component after phase adjustment. A distortion overlapping section overlaps the baseband signal with a phase-inverted distortion component of the baseband distortion component. A converter converts the non-linear distortion component output from the distortion extractor into a DC component. A controller automatically controls an attenuation of the output signal of the high-power amplifier to minimize the DC component output from the converter.

Claims

1. A method for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation, the transmitter having a distortion extractor for extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal, a quadrature modulator for quadrature modulating the non-linear distortion component into a baseband distortion component after phase adjustment, and a distortion overlapping section for overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, the method comprising the steps of:

attenuating an output signal of the high-power amplifier by a gain of the high-power amplifier when the high-power amplifier generates an amplified signal, and extracting a non-linear distortion component by subtracting a phase-adjusted input signal of the high-power amplifier from the attenuated output signal; and

converting the non-linear distortion component into a DC (Direct Current) component, and automatically controlling an attenuation of the output signal of the high-power amplifier to minimize the DC component.

2. An apparatus for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation, the transmitter having a distortion extractor for extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal, a quadrature modulator for quadrature modulating the non-linear distortion component into a baseband distortion component after phase adjustment, and a distortion overlapping section for overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, the circuit comprising:

a converter for converting the non-linear distortion component output from the distortion extractor into a DC component; and

a controller for automatically controlling an attenuation of the output signal of the high-power amplifier to minimize the DC component output from the converter.

3. The apparatus as claimed in claim 2, wherein the distortion extractor comprises:

an attenuator for attenuating the output signal of the high-power amplifier by a gain equal to the gain of the high-power amplifier, when the high-power amplifier outputs an amplified signal;

a phase shifter for shifting a phase of an input signal of the high-power amplifier; and

a subtracter for subtracting an output signal of the phase shifter from an output signal of the attenuator;

wherein the attenuator, under the control of the controller, automatically controls an attenuation of the output signal of the high-power amplifier to minimize the DC component output from the converter.

4. A method for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation, the transmitter having a distortion extractor for extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal, a quadrature modulator for quadrature modulating the non-linear distortion component into a baseband distortion component after phase adjustment, and a distortion overlapping section for overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, the method comprising the step of:

suspending an operation of overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, when an input power level of the high-power amplifier drops below a power level at a point where an input power-to-ACPR characteristic of the high-power amplifier becomes worse during non-linear distortion compensation control than during suspension of the non-linear distortion compensation control.

5. An apparatus for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation, the transmitter having a distortion extractor for extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal, a quadrature modulator for quadrature modulating the non-linear distortion component into a baseband distortion component after phase adjustment, and a distortion overlapping section for overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, the circuit comprising:

a switch for switching a signal input into said distortion overlapping section, said signal included in a feedback loop formed between the distortion extractor and the distortion overlapping section;

a power detector for detecting an input power level of the high-power amplifier;

a controller for receiving the signal detected by the power detector and turning OFF the switch when the input power level of the high-power amplifier drops below a power level at a point where an input power-to-ACPR characteristic of the high-power amplifier becomes worse during non-linear distortion compensation control than during suspension of the non-linear distortion compensation control.

6. An apparatus for compensating for non-linear distortion generated during non-linear high-power amplification in a transmitter after quadrature modulation, the transmitter having a distortion extractor for extracting a non-linear distortion component from a non-linearly high-power amplified modulated signal, a quadrature modulator for quadrature modulating the non-linear distortion component into a baseband distortion component after phase adjustment, and a distortion overlapping section for overlapping the baseband signal with a phase-inverted distortion component of the baseband distortion component, the circuit comprising:

a power detector for detecting an input power level of the high-power amplifier; and

a controller for receiving the signal detected by the power detector and disabling one of a plurality of function elements included in a feedback loop formed between the distortion extractor and the distortion overlapping section, when the input power level of the high-power amplifier drops below a power level at a point where an input power-to-ACPR characteristic of the high-power amplifier becomes worse during non-linear distortion compensation control than during suspension of the non-linear distortion compensation control.