Predistortion Linearizer Calibration Without Direct Phase Measurement
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Solution Overview
Problem
Existing methods for compensating nonlinear distortion in electronic components, such as power amplifiers, require direct phase measurement and calibration, which is challenging, especially in environments like satellites where implementing a time and phase reference is difficult, and cannot adapt to equipment drift or changes in environmental conditions.
Innovation Solution
A method that adjusts the predistortion linearizer settings during operation by applying a bifrequency test signal to measure and minimize the dissimilarity in the signal spectrum, allowing for real-time compensation of nonlinear distortion without direct phase measurement, using a calibration device to determine and apply predistortion parameters that minimize AM/PM and AM/AM distortions across a range of power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct phase measurement and calibration methods are used, then linearization accuracy is improved, but device complexity and difficulty of implementation increase significantly
Solution Approach 1:
The patent introduces an intermediary approach by using power spectral density measurements as a mediator between the input and output signals. Instead of directly measuring phase differences which requires complex reference systems, the method uses PSD measurements at the output to infer nonlinearity characteristics. This intermediary measurement technique simplifies the calibration process while maintaining linearization accuracy.
Solution Approach 2:
The patent replaces the mechanical/reference-based phase measurement system with a spectral analysis approach. By substituting direct phase measurement (which requires time and phase references) with power spectral density analysis, the method eliminates the need for complex reference systems while achieving the same linearization goal through a different measurement paradigm.
2Loss of energy
If predistortion linearizer is placed upstream of the amplifier, then electrical efficiency is improved, but measurement and calibration difficulty increase
Solution Approach 1:
The patent enables the predistortion linearizer system to perform self-calibration by using its own output signal characteristics. The power spectral density measurements are taken from the linearizer-amplifier assembly itself, and the calibration process uses these self-generated measurements to adjust predistortion parameters, eliminating the need for external complex measurement equipment.
Solution Approach 2:
The patent implements a feedback mechanism where the power spectral density of the output signal is continuously monitored and used to adjust the predistortion parameters. This feedback loop allows the system to automatically compensate for nonlinearities and adapt to changes in operating conditions, simplifying the calibration process while maintaining efficiency.
3Device complexity
If fixed predistortion settings are used, then device simplicity is maintained, but adaptability to environmental changes and equipment drift decreases
Solution Approach 1:
The patent transforms the static predistortion settings into a dynamic system that can adapt to changing conditions. By implementing a calibration process that can be performed at different power levels and that uses measured PSD characteristics to adjust parameters, the system becomes dynamic and adaptable to environmental changes and equipment drift while maintaining relative simplicity.
Solution Approach 2:
The patent enables parameter changes in the predistortion settings based on measured performance characteristics. The calibration process determines optimal predistortion parameters by analyzing power spectral density measurements, allowing the system to adjust its operating parameters to maintain linearity under varying conditions without requiring a completely complex adaptive architecture.
Data Source
AI summary
Method for calibrating a linearizer and linearized electronic component the method comprises predistortion, in a predistortion linearizer, of a signal upstream of an electronic component to compensate nonlinear distortion. Determining predistortion setting parameters comprises applying a bifrequency test signal to the component and measuring the relative amplitudes of the lines at the output of the component. A variable indicative of the magnitude |Kp| of the AM/PM conversion coefficient of the component is calculated on the basis of these measurements. The predistortion setting parameters are adjusted so as to minimize |Kp|. The method may in particular be implemented in a linearized amplifier device and in an amplifier test bench.