Digital Calibration of Analog Distortion Using Split Front-End

Solution Overview

Problem

Conventional methods for correcting analog distortion in communication systems are power-hungry and often insufficient, relying on complex techniques such as signal properties, pilot tone crosstalk, and master/slave matching.

Innovation Solution

A receiver circuit design that splits analog signals into multiple paths, injects a difference signal to detect distortion, and uses a low-noise amplifier and low-power ADC modules to convert and correct harmonic distortion through a least means squared (LMS) feedback loop, minimizing power consumption while effectively canceling distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional distortion correction circuitry is used, then distortion correction capability is improved, but power consumption increases significantly

Engineering Contradiction:

Improvedistortion correction capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces complex analog distortion correction circuitry with a digital signal processing approach. An analog-to-digital converter converts the distorted analog signal to digital form, where distortion correction is performed using digital signal processing algorithms. This substitution of mechanical/analog systems with digital systems achieves effective distortion correction while significantly reducing power consumption compared to conventional analog correction circuitry.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a simplified analog front-end that creates a distorted copy of the received signal. This distorted copy is then converted to digital form and used as input for the distortion correction algorithm. The correction process uses this copied distorted signal to calculate and apply the appropriate correction factors, achieving accurate distortion compensation without requiring complex analog correction circuitry.

Inventive Principle:

Principle #26Copying

2Reliability

If conventional distortion correction techniques are used, then distortion correction is attempted, but the circuit complexity increases

Engineering Contradiction:

Improvedistortion correction capabilityVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex analog distortion correction circuitry with a digital signal processing approach. An analog-to-digital converter converts the distorted analog signal to digital form, where distortion correction is performed using digital signal processing algorithms. This substitution of mechanical/analog systems with digital systems achieves effective distortion correction while significantly reducing power consumption compared to conventional analog correction circuitry.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters of the analog front-end components, specifically using non-linear amplifiers that operate in their non-linear region to intentionally generate predictable distortion. By controlling and characterizing these distortion parameters, the system can digitally correct them later, simplifying the analog circuit design while maintaining correction capability.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If simple non-linear amplifiers are used, then power consumption is reduced, but harmonic distortion increases

Engineering Contradiction:

Improvepower consumptionVSAvoidharmonic distortion

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful harmonic distortion generated by simple non-linear amplifiers into a useful signal characteristic. The distortion products are not eliminated at the analog stage but are instead preserved and transferred to the digital domain. There, sophisticated signal processing algorithms analyze the distorted signal, identify the distortion components, and calculate correction factors. This approach transforms what was previously a harmful analog distortion problem into a solvable digital signal processing task, allowing the use of power-efficient non-linear amplifiers.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces complex analog distortion correction circuitry with a digital signal processing approach. An analog-to-digital converter converts the distorted analog signal to digital form, where distortion correction is performed using digital signal processing algorithms. This substitution of mechanical/analog systems with digital systems achieves effective distortion correction while significantly reducing power consumption compared to conventional analog correction circuitry.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9031177B2Digital calibration of analog distortion using split analog front-end

Publication Date: 2015.05.12 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A receiver is disclosed that is capable of correcting for harmonic distortion injected into received analog signals. The receiver splits the analog signal in the analog front-end and modifies the split analog signals with a difference signal. After amplification and/or sampling, the modified analog signals are recombined in a main data pathway and are kept separate in a secondary pathway. Utilizing the difference signal, a feedback loop that includes distorters and an LMS filter detects the distortion coefficient of the harmonic distortion. A distorter in the main data pathway utilizes the detected distortion coefficient to correct the harmonic distortion in the analog signal.