Transmitting Arrangement Feedback Distortion Correction
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Solution Overview
Problem
Modern transceivers face challenges in achieving linear signal amplification due to the use of power amplifiers with non-linear transfer characteristics, leading to AM/AM and AM/PM distortions, which require large predistortion coefficients and complex calibration processes.
Innovation Solution
A transmitting arrangement that includes a feedback path with a conversion device using a frequency-modulated local-oscillator signal to determine and compensate for distortions caused by the power amplifier, allowing for predistortion to maintain linearity, and a distortion unit with adjustable coefficients to correct nonlinear transfer characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If predistortion units with large numbers of coefficients are used to correct AM/AM and AM/PM distortions, then distortion correction accuracy is improved, but memory consumption and calibration complexity increase
Solution Approach 1:
The patent applies preliminary action by using a feedback path to measure the actual distortions produced by the power amplifier before transmission, and using these measurements to dynamically adjust predistortion coefficients. This allows the system to prepare correction parameters based on real-time conditions rather than relying on large pre-stored coefficient tables, thereby reducing memory requirements while maintaining correction accuracy.
Solution Approach 2:
The patent changes the parameter approach from using a large fixed set of predistortion coefficients to dynamically adjusting a smaller set of coefficients based on feedback measurements. The system measures actual distortion parameters through the feedback path and adjusts the predistortion parameters accordingly, reducing memory consumption while adapting to changing conditions such as temperature and standing wave ratio variations.
2Use of energy by moving object
If power amplifiers with non-linear transfer characteristics are used to reduce power consumption, then energy efficiency is improved, but signal linearity deteriorates due to AM/AM and PM/AM distortions
Solution Approach 1:
The patent applies preliminary anti-action by introducing predistortion units that pre-compensate for the non-linear distortions before the signal enters the power amplifier. The feedback path measures the actual distortions, and the predistortion coefficients are adjusted to counteract these distortions in advance, ensuring that the output signal remains linear despite the non-linear characteristics of the power amplifier.
Solution Approach 2:
The patent implements feedback by coupling a feedback path from the output of the power amplifier back to the predistortion units. This feedback path measures the actual distortions produced by the amplifier and uses these measurements to dynamically adjust the predistortion coefficients, creating a closed-loop system that maintains signal linearity while allowing the use of non-linear power amplifiers for energy efficiency.
3Measurement precision
If elaborate calibration measures are performed during production to determine predistortion coefficients, then distortion correction accuracy is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent applies self-service by enabling the system to automatically determine and adjust its own predistortion coefficients through the feedback path during operation. Instead of requiring elaborate manual calibration during production, the system uses its own output signal, fed back through the feedback path, to measure distortions and automatically adjust the predistortion parameters, significantly reducing calibration time and complexity.
Solution Approach 2:
The feedback path enables the system to automatically measure the distortions produced by the power amplifier and use these measurements to determine the appropriate predistortion coefficients. This feedback mechanism replaces the need for elaborate manual calibration procedures during production, allowing the system to self-calibrate during operation and reducing both calibration time and manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the determination and correction of distortions, reducing memory consumption and calibration complexity while maintaining signal linearity, even with unpredictable changes such as temperature fluctuations and standing wave ratio changes.
Implementation Method 1
The phase component, the so-called phase modulation word, is used for driving a phase-locked loop which generates a frequency- or phase-modulated carrier signal
Implementation Method 2
The gain of the power amplifier is changed as a function of the amplitude component, the amplitude modulation word. This results in a frequency or phase modulation with simultaneous amplitude modulation of the carrier signal
Implementation Method 3
In the feedback path, demodulation occurs and conversion into the in-phase component I' and the quadrature component Q' is performed
Data Source
AI summary
A transmitting arrangement includes a first signal input for supplying a frequency modulation signal, a second signal input for supplying an amplitude modulation signal, a phase-locked loop and an amplifying device. The latter is connected with a control connection to the second signal input. A signal input of the amplifying device is connected to the output of the phase-locked loop. A conversion device with a local-oscillator input is provided in a feedback path. The conversion device is constructed for splitting a signal, coupled out from an output of the amplifying device, into a first component and a second component with the aid of a local-oscillator signal. In this arrangement, the local-oscillator input is coupled to the output of the phase-locked loop.