Analog Predistortion Linearizer With Dynamic Frequency Compensation

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Solution Overview

Problem

Conventional predistorters struggle to effectively counteract saturation distortion in power amplifiers across a wide frequency band, as the distortion characteristics of amplifiers change significantly with frequency, leading to inadequate linearization and limited operating power range.

Innovation Solution

An analog predistortion linearizer system with dynamic frequency compensation, which includes a frequency detector, controller, and predistorter that automatically adjusts predistortion characteristics based on detected frequency, generating a predistorted drive signal to counteract gain magnitude and phase distortion in high-power amplifiers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional predistorter is designed to counteract amplifier distortion at one particular frequency, then the linear operating power is extended at that frequency, but the predistorter becomes inadequate for wideband applications requiring multiple frequencies

Engineering Contradiction:

Improvefrequency band coverageVSAvoiddistortion counteraction accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The predistorter is made dynamically adjustable through a frequency detector that identifies the operating frequency and a controller that modifies predistorter parameters accordingly. This allows the predistorter to adapt its distortion counteraction characteristics to match the amplifier's frequency-dependent behavior, enabling effective operation across a wide frequency band rather than being fixed for a single frequency

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the predistorter's operational parameters based on the detected frequency. By detecting the frequency and adjusting the predistorter's characteristics (such as predistortion magnitude and phase) to match the amplifier's distortion profile at that frequency, the system maintains accurate distortion counteraction across varying frequencies

Inventive Principle:

Principle #35Parameter changes

2Power

If the amplifier operates at higher power levels to increase output capacity, then the power output increases, but saturation distortion increases and fidelity is lost

Engineering Contradiction:

Improveoutput powerVSAvoidsaturation distortion

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The predistorter applies preliminary anti-action by pre-distorting the input signal with inverse distortion characteristics before the amplifier processes it. This preliminary distortion is designed to counteract the amplifier's saturation distortion, so that when the amplifier operates at higher power levels, the combined effect of predistortion and amplification results in reduced overall distortion and maintained signal fidelity

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The system converts the harmful saturation distortion into a benefit by measuring and characterizing the amplifier's distortion behavior, then using that information to create a predistorter that applies compensating distortion. The amplifier's inherent nonlinearity, which normally degrades signal quality, is transformed into a predictable characteristic that can be compensated for, enabling high-power operation with maintained fidelity

Inventive Principle:

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

3Adaptability or versatility

If a predistorter is designed with fixed characteristics for a single frequency, then the device complexity is low, but it cannot effectively handle wideband applications with varying frequency characteristics

Engineering Contradiction:

Improvefrequency adaptabilityVSAvoidpredistorter control system

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system employs feedback through a frequency detector that continuously monitors the operating frequency and provides this information to a controller. This feedback loop enables the predistorter to automatically adjust its characteristics to match the current operating conditions, providing frequency adaptability without requiring complex manual reconfiguration or multiple fixed predistorters for different frequencies

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10284237B2Systems and methods for a predistortion linearizer with frequency compensation

Publication Date: 2019.05.07 MISSION MICROWAVE TECH INC

AI summary

An analog predistortion linearizer system with dynamic frequency compensation for automatically adjusting predistortion characteristics based on a detected frequency includes a frequency detector configured to generate at least one frequency detection signal in response to receiving an amplifier drive signal, the frequency detection signal including a frequency indicator that indicates the frequency of the amplifier drive signal. Moreover, the system also includes a controller communicatively coupled to the frequency detector and configured to generate a predistorter control signal in response to receiving the frequency detection signal from the frequency detector, and a predistorter communicatively coupled to i) the frequency detector and ii) the controller, the predistorter configured to generate a predistorted amplifier drive signal based on at least the predistorter control signal.