Composite Amplifier Distortion Compensation Across Transmitting Branches
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Solution Overview
Problem
Composite amplifiers, such as Doherty and Chireix amplifiers, face challenges in compensating for signal distortions in multiple transmitting branches, which are difficult to observe and correct due to the mixing of errors from individual IQ-modulators, leading to residual errors in the transmitter output.
Innovation Solution
A method and system that derive signal distortions in each transmitting branch by observing the output signal from the composite amplifier, using a model to determine the contribution of each parameter to the distortion, and adjusting compensating parameters to minimize errors, allowing for individual compensation without additional observation receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple transmitting branches are used in composite amplifiers to improve efficiency, then power efficiency is improved, but signal distortion compensation becomes more difficult due to mixing of errors from individual IQ-modulators
Solution Approach 1:
The patent segments the error analysis by utilizing different operating regions of the composite amplifier. At low output levels, only the main amplifier is active, allowing isolation and measurement of its IQ-modulator errors. At high output levels, both main and auxiliary amplifiers are active, allowing measurement of combined errors. This segmentation enables separate characterization of error sources without requiring additional observation receivers for each branch.
Solution Approach 2:
The patent performs preliminary error characterization by measuring and storing error parameters at different operating regions before actual signal transmission. The error parameters measured at low and high output levels are used to calculate compensation parameters in advance, which are then applied to pre-compensate the input signal. This preliminary action simplifies real-time compensation operations.
2Measurement precision
If additional observation receivers are added to each transmitting branch to improve measurement precision, then signal distortion detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the error measurement function into a single observation receiver that monitors the composite output signal. By mathematically separating the error contributions from different amplifiers based on their known operating regions and characteristics, the system achieves accurate error detection without requiring separate observation receivers for each transmitting branch. This combining approach reduces hardware complexity while maintaining measurement precision.
Data Source
AI summary
A method for compensating signal distortions in multiple transmitting branches entering a composite amplifier.