Band-Limited DPD Adaptation for PA Linearization Bandwidth Control

Solution Overview

Problem

Conventional digital predistortion systems for power amplifiers face challenges with bandwidth expansion, leading to increased sampling rate requirements and resource consumption, particularly in wireless communications where large bandwidths are necessary.

Innovation Solution

A band-limited adaptation subsystem is introduced, which reduces the observed bandwidth by up to 2 times the desired bandwidth of the power amplifier output signal, thereby lowering the sampling rate requirements and reducing complexity and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional digital predistortion systems observe the full bandwidth of non-linear distortion products (up to NMAX-ORDER times the desired bandwidth), then compensation accuracy for power amplifier non-linearities is improved, but sampling rate requirements and system complexity increase significantly

Engineering Contradiction:

Improvecompensation accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the high-frequency distortion products beyond the desired bandwidth from the observation signal. By applying a band-limiting filter that eliminates frequency components above the desired bandwidth, the system retains only the relevant in-band distortion products for adaptation, thereby reducing the bandwidth observation requirement while maintaining compensation accuracy for the desired signal band.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different quality requirements to different frequency regions. Instead of uniformly observing and processing the entire expanded bandwidth, the system focuses computational resources and observation efforts only on the local region of interest (the desired bandwidth), where the compensation is actually needed. This localized approach reduces overall system complexity while preserving essential compensation functionality.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If conventional digital predistortion systems observe the full bandwidth of non-linear distortion products, then compensation accuracy for power amplifier non-linearities is improved, but sampling rate requirements increase

Engineering Contradiction:

Improvecompensation accuracyVSAvoidsampling rate

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent extracts and removes the high-frequency distortion products beyond the desired bandwidth from the observation signal. By applying a band-limiting filter that eliminates frequency components above the desired bandwidth, the system retains only the relevant in-band distortion products for adaptation, thereby reducing the bandwidth observation requirement while maintaining compensation accuracy for the desired signal band.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If conventional digital predistortion systems observe the full bandwidth of non-linear distortion products, then compensation accuracy for power amplifier non-linearities is improved, but power consumption increases

Engineering Contradiction:

Improvecompensation accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts and removes the high-frequency distortion products beyond the desired bandwidth from the observation signal. By applying a band-limiting filter that eliminates frequency components above the desired bandwidth, the system retains only the relevant in-band distortion products for adaptation, thereby reducing the bandwidth observation requirement while maintaining compensation accuracy for the desired signal band.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by observing and processing only the necessary portion of the signal bandwidth (the desired bandwidth) rather than the full expanded bandwidth. This partial observation approach provides sufficient information for effective compensation while significantly reducing computational load and power consumption associated with processing the entire spectrum.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS8890609B2Systems and methods for band-limited adaptation for PA linearization

Publication Date: 2014.11.18 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Systems and methods are disclosed for providing band-limited power amplifier linearization. In one embodiment, a system includes a power amplifier configured to amplify a power amplifier input signal to provide a power amplifier output signal and a digital predistortion system configured to compensate for up to a predefined maximum order of non-linearity of the power amplifier. The digital predistortion system includes a band-limited adaptation subsystem. As compared to conventional adaptation subsystems, the band-limited adaptation subsystem is significantly less complex and consumes less power.