Envelope Tracking Compensation for Power Amplifier Filter Distortion
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Solution Overview
Problem
Power amplifiers in RF communication systems face distortion due to uncontrolled voltage swing caused by loading effects from supply voltage filters, leading to inefficiencies and performance degradation.
Innovation Solution
An envelope tracking system that includes digital modeling circuitry to model and compensate for the supply voltage filter's effects, using a power amplifier supply voltage generated based on an envelope signal corresponding to the RF signal, and digital pre-distortion to correct for distortion, thereby improving power added efficiency and reducing adjacent channel leakage ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a supply voltage filter is used to provide stable power to the power amplifier, then power stability is improved, but voltage swing and distortion are introduced due to loading effects
Solution Approach 1:
The system performs preliminary action by extracting the envelope of the RF signal before amplification and using it to dynamically adjust the power amplifier's supply voltage. This pre-processing of the power supply based on signal characteristics prevents distortion before it occurs, rather than attempting to correct it after the fact.
Solution Approach 2:
The invention transforms the static, fixed supply voltage into a dynamic, time-varying supply voltage that tracks the envelope of the RF signal. This dynamic adjustment allows the power amplifier to maintain optimal operating conditions throughout the signal cycle, reducing distortion while preserving power stability through active control.
2Device complexity
If conventional fixed power supply is used, then system complexity is reduced, but power added efficiency deteriorates
Solution Approach 1:
The system implements self-service by using the RF signal's own envelope information to control its power supply. The envelope extractor derives control signals directly from the transmitted signal, and the power amplifier automatically adjusts its operating point based on this self-generated feedback, eliminating the need for external complex control systems while improving efficiency.
3Use of energy by moving object
If dynamic envelope tracking is implemented to improve efficiency, then power added efficiency is improved, but system complexity increases due to additional circuitry
Solution Approach 1:
The invention merges the envelope detection and power control functions into a unified system where the envelope extractor and voltage controller work as an integrated pair. By combining these functions and using the same envelope information for both signal processing and power control, the system achieves dynamic efficiency improvement without proportionally increasing complexity.
Data Source
AI summary
Envelope tracking systems with modeling for power amplifier supply voltage filtering are provided herein. In certain embodiments, an envelope tracking system includes a supply voltage filter, a power amplifier that receives a power amplifier supply voltage through the supply voltage filter, and an envelope tracker that generates the power amplifier supply voltage. The power amplifier provides amplification to a radio frequency (RF) signal that is generated based on digital signal data, and the envelope tracker generates the power amplifier supply voltage based on an envelope signal corresponding to an envelope of the RF signal. The envelope tracking system further includes digital modeling circuitry that models the supply voltage filter and operates to digitally compensate the digital signal data for effects of the supply voltage filter, such as distortion.