Envelope Tracking Waveform Generation for Power Amplifier Efficiency
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Solution Overview
Problem
Traditional envelope tracking implementations in wireless communication devices face inefficiencies due to misalignment between the ET supply waveform and the RF envelope waveform, leading to degradation in adjacent channel leakage ratio and error vector magnitude, as well as increased noise emission in the receive band.
Innovation Solution
The proposed solution involves constructing an ET waveform that closely follows the RF signal envelope by introducing a delay to allow for analysis of the modulation, considering amplifier slew rates and power supply limitations, and dynamically adjusting the ET waveform synthesis to maintain alignment and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional envelope tracking is implemented with fixed waveform alignment, then power consumption is reduced, but adjacent channel leakage ratio and error vector magnitude deteriorate
Solution Approach 1:
The patent applies dynamics by making the ET waveform alignment dynamic rather than fixed. The system continuously adjusts the ET waveform to track the RF envelope waveform in real-time, adapting to changing signal conditions. This dynamic adjustment resolves the contradiction by maintaining both low power consumption (through envelope tracking) and high measurement precision (through continuous alignment optimization).
Solution Approach 2:
The patent implements feedback mechanisms where the system monitors the alignment between ET and RF envelope waveforms and adjusts the ET waveform accordingly. This feedback loop ensures that the ET waveform remains optimally aligned with the RF signal envelope, preventing degradation in adjacent channel leakage ratio and error vector magnitude while maintaining power savings from envelope tracking.
2Measurement precision
If ET waveform is delayed to allow modulation analysis, then alignment between ET and RF signals is improved, but response time increases
Solution Approach 1:
The patent applies preliminary action by performing modulation analysis in advance on buffered RF signals. The system collects a buffer of RF envelope waveforms and completes modulation analysis before the ET waveform is generated. This allows the delayed ET waveform to still be properly aligned when transmitted, resolving the contradiction between improved alignment and increased response time.
Solution Approach 2:
The patent uses partial action by implementing selective buffering and analysis only when necessary for alignment optimization. The system balances the degree of delay applied to ET waveforms based on actual alignment needs, avoiding excessive delay that would unnecessarily increase response time while still achieving sufficient alignment improvement.
3Measurement precision
If amplifier slew rates are constrained to avoid high attack rates, then spectral purity is improved, but power delivery speed decreases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the slew rate constraints of the amplifier based on signal conditions. The system modifies attack rates and decay rates of the ET waveform to match the amplifier's capabilities, preventing spectral regrowth and improving spectral purity while maintaining adequate power delivery speed through optimized parameter selection.
Data Source
AI summary
A method and apparatus is provided to improve upon the efficiency of a power amplifier. Suitable hardware/software in the form of circuitry, logic gates, and/or code functions to construct an envelope tracking waveform of an input communications signal and modulate the input supply voltage based on power amplifier circuitry operational parameters such as slew rates.