Configurable Delay Distortion Compensation Circuit

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Solution Overview

Problem

Existing distortion compensation techniques for directly-modulated lasers in optical transmitters fail to accommodate varying RF loading conditions, leading to misalignment of predistortion and resulting distortion products, particularly in multi-channel RF applications.

Innovation Solution

A distortion compensation circuit with a configurable delay segment is introduced, allowing for different delay settings in the primary signal path to align with distortion products generated in the secondary signal path, ensuring proper compensation for composite second-order and third-order intermodulation distortions across various RF loading conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed delay is used in the primary signal path, then the predistortion can be aligned for a specific RF loading condition, but the system cannot accommodate different RF loading conditions

Engineering Contradiction:

Improveaccommodation of different RF loading conditionsVSAvoidcomplexity of delay configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the Dynamics principle by implementing a configurable delay segment that can be dynamically adjusted to provide different delay settings. This allows the predistortion circuit to adapt to different RF loading conditions (such as different numbers of active carriers) by changing the delay value, thereby resolving the contradiction between fixed delay alignment and adaptability to varying conditions.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the predistortion is generated for one RF loading condition, then the distortion compensation is optimized for that condition, but misalignment occurs under different RF loading conditions

Engineering Contradiction:

Improvedistortion compensation accuracyVSAvoidperformance across different RF loading conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies theParameter changesprinciple by configuring the delay segment to provide different delay settings based on different RF loading conditions. When the number of active carriers changes, the delay value is adjusted accordingly to maintain proper alignment between the predistortion signal and the RF signal, thereby preserving distortion compensation accuracy across varying operational conditions.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a simple fixed delay circuit is used, then the device complexity is low, but the predistortion alignment is incorrect for varying RF loading conditions

Engineering Contradiction:

Improvesimplicity of delay configurationVSAvoidalignment precision of predistortion

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements a configurable delay segment that can be dynamically adjusted to provide different delay settings. This dynamic adjustment capability allows the system to maintain high alignment precision for predistortion across different RF loading conditions while keeping the overall architecture relatively simple through controlled configurability rather than complete complexity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8670675B2System and method for distortion compensation including configureable delay

Publication Date: 2014.03.11 APPLIED OPTOELECTRONICS INC(US)

AI summary

A distortion compensation circuit including a configurable delay may be used with one or more non-linear elements, such as a laser, to compensate for distortion generated by the non-linear element(s), for example, in broadband RF applications. Embodiments of the distortion compensation circuit may include a primary signal path with a configurable delay segment and a secondary signal path including at least one distortion generator. The configurable delay segment may be selectively configured to provide different delay settings to accommodate different RF loading conditions such that the delayed RF signal on the primary signal path is aligned with the distortion products generated on the secondary signal path when combined to form an RF signal with distortion compensation.