PA Supply Filter Modeling for Envelope Tracking Distortion Control
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Solution Overview
Problem
Power amplifiers in RF communication systems face challenges in managing power efficiently, leading to uncontrolled voltage swings and distortion in RF signal outputs due to loading effects from supply voltage filters, which affect power amplifier efficiency and signal quality.
Innovation Solution
An envelope tracking system that includes a supply voltage filter, a power amplifier, and digital modeling circuitry to model and compensate for distortion in the supply voltage filter, using techniques like digital pre-distortion and coordinate rotation digital computation to generate and shape envelope signals for precise voltage control and distortion correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a supply voltage filter is used to stabilize power amplifier supply voltage, then power supply stability is improved, but voltage swings and distortion are introduced due to loading effects
Solution Approach 1:
The system performs preliminary action by measuring the supply voltage through the filter and using digital signal processing to predict and compensate for distortion before it affects the RF output. The digital signal processor calculates compensation signals in advance based on the measured supply voltage characteristics, applying corrections proactively rather than reactively.
Solution Approach 2:
The system implements feedback by continuously monitoring the supply voltage through the filter and using this information to adjust the RF drive signal. The digital signal processor uses the measured supply voltage to generate compensation signals that are fed back to correct distortion, creating a closed-loop control system that adapts to changing conditions.
2Use of energy by moving object
If power is reduced to prolong battery life, then energy consumption is improved, but signal quality and transmission effectiveness deteriorate
Solution Approach 1:
The system applies parameter changes by dynamically adjusting the supply voltage to the power amplifier based on the RF signal envelope. Instead of using a fixed high voltage that consumes excessive power, the system varies the voltage parameter to match the instantaneous signal requirements, reducing power consumption during low-signal periods while maintaining adequate voltage during high-signal periods to preserve signal quality.
3Use of energy by moving object
If envelope tracking is used to improve power efficiency, then energy consumption is reduced, but complexity of voltage control increases
Solution Approach 1:
The system uses an intermediary approach by introducing a digital signal processor as a mediator between the RF signal and the power amplifier control. This intermediary component handles the complex voltage control calculations and signal processing, isolating the complexity from the core envelope tracking mechanism and making the overall system more manageable and implementable.
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 enhances power added efficiency (PAE), improves adjacent channel leakage ratio (ACLR), and reduces error vector magnitude (EVM), effectively addressing mismatch changes and memory effects in power amplifier systems.
Implementation Method 1
a supply voltage filter, a power amplifier configured to amplify the radio frequency signal and to receive power from a power amplifier supply voltage through the supply voltage filter
Implementation Method 2
an envelope tracker configured to generate the power amplifier supply voltage based on an envelope signal corresponding to an envelope of the radio frequency signal
Implementation Method 3
a power amplifier configured to amplify the radio frequency signal
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.