Volterra Equalizer Coefficients for Non-Linear Distortion Compensation

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Solution Overview

Problem

Linear equalizers are insufficient for equalizing non-linear electronic systems, as they fail to accurately compensate for non-linear distortions, especially when the electronic components exhibit non-linear behavior or require narrow precision.

Innovation Solution

A method using a Volterra filter module to determine filter coefficients by describing the non-linear electronic system and the Volterra filter module in terms of Volterra series, employing a Pth order inverse technique to derive reference transfer functions and coefficients, which are then used to compensate for non-linear distortions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a linear equalizer is used to equalize the electronic component, then the equalization process is simple and computationally efficient, but it fails to accurately compensate for non-linear distortions when the electronic component exhibits non-linear behavior

Engineering Contradiction:
Improveequalization accuracyVSAvoidequalizer structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent transitions from linear equalization parameters to Volterra series parameters, changing the mathematical model from first-order linear relationships to higher-order non-linear relationships. This allows accurate compensation of non-linear distortions by incorporating second-order and third-order kernel functions that capture non-linear behavior while maintaining a structured approach to complexity management.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The Volterra filter is segmented into multiple kernel functions of different orders (first-order, second-order, third-order kernels). Each kernel handles specific aspects of the non-linear distortion, allowing the complex equalization problem to be divided into manageable components that can be computed and adjusted independently.

Inventive Principle:
Principle #1Segmentation

2Productivity

If the maximum order of the Volterra series is restricted to three, then the numerical complexity and computing resources are minimized, but higher-order non-linear distortions may not be fully compensated

Engineering Contradiction:
Improvecomputing efficiencyVSAvoidnon-linear distortion compensation precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies partial action by limiting the Volterra series to three orders, acknowledging that while higher-order terms exist, the first three orders provide sufficient compensation for most practical non-linear distortions. This partial approach achieves acceptable precision while avoiding the excessive computational burden of including all possible higher-order terms.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

By changing the parameter of maximum series order from a theoretical infinite value to a practical limit of three, the patent optimizes the balance between compensation precision and computing efficiency. This parameter change reflects the practical observation that third-order non-linearities dominate in most electronic systems, making higher-order terms negligible for many applications.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4084425A1Method for determining filter coefficients and equalizer module
Publication Date: 2022.11.02 ROHDE & SCHWARZ GMBH & CO KG
  • EP4084425A1 patent drawingFigure 1~2
  • EP4084425A1 patent drawingFigure 3
  • EP4084425A1 patent drawingFigure 4

AI summary

A method for determining filter coefficients of an equalizer module (14) for equalizing a non-linear electronic system is described. The equalizer module (14) comprises a Volterra filter module (16). The method comprises the following steps: - processing an input signal by means of the non-linear electronic system, thereby obtaining an output signal; - providing a first mathematical model, wherein the first mathematical model describes the non-linear electronic system in terms of a first Volterra series; - providing a second mathematical model, wherein the second mathematical model describes the Volterra filter module (16) in terms of a second Volterra series; - determining reference transfer functions of the Volterra filter module (16) by means of a Pth order inverse technique based on the first Volterra series; and - determining filter coefficients of the Volterra filter module (16) based on the determined reference transfer functions and based on the second Volterra series. Further, an equalizer module (14) for equalizing a non-linear electronic system and an electronic device (10) are described.