Envelope-Stacking RF Power Amplifier for PAPR Efficiency and Linearity
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Solution Overview
Problem
High peak-to-average power ratios (PAPRs) in non-constant-envelope signals for 5G wireless communications lead to stringent linearity requirements for RF amplifiers, causing efficiency reduction and heat dissipation issues due to voltage and current clipping, which affects the overall power management and battery life of wireless devices.
Innovation Solution
An envelope stacking power amplifier system dynamically switches between stacked and unstacked configurations of RF amplifiers based on input signals, using a stack/unstack controller to manage power supplies and ensure linearity, thereby reducing current consumption and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the RF amplifier operates in saturated power region to maximize efficiency, then power efficiency is improved, but linearity deteriorates due to voltage and current clipping
Solution Approach 1:
The RF amplifier is divided into multiple amplification stages (first RF amplifier and second RF amplifier) that can operate independently or in combination. This segmentation allows different parts of the signal envelope to be amplified by different stages, with the first amplifier handling high-power segments and the second amplifier handling low-power segments, thereby maintaining both efficiency and linearity across the full power range
Solution Approach 2:
The invention dynamically switches between stacked and unstacked configurations based on the input signal envelope. The switching configuration responds to envelope transitions, dynamically reconfiguring the amplifier stages to maintain optimal operation points. This dynamic adaptation allows the system to maintain linearity during envelope transitions while maximizing efficiency during steady-state operation
2Reliability
If the RF amplifier backs off from saturated power region to maintain linearity, then linearity is improved, but power efficiency deteriorates dramatically
Solution Approach 1:
The RF amplifier is divided into multiple amplification stages (first RF amplifier and second RF amplifier) that can operate independently or in combination. This segmentation allows different parts of the signal envelope to be amplified by different stages, with the first amplifier handling high-power segments and the second amplifier handling low-power segments, thereby maintaining both efficiency and linearity across the full power range
Solution Approach 2:
The invention merges the output signals from multiple RF amplifier stages through a combining network. The first and second RF amplifiers operate in parallel and their outputs are combined to produce the final amplified signal. This merging allows the system to leverage the high efficiency of saturated operation from the first amplifier while the second amplifier provides the necessary linearity for low-power segments
3Productivity
If complex modulation schemes are used to achieve high data rates, then data rate is improved, but PAPR increases causing efficiency reduction
Solution Approach 1:
The invention dynamically switches between stacked and unstacked configurations based on the input signal envelope. The switching configuration responds to envelope transitions, dynamically reconfiguring the amplifier stages to maintain optimal operation points. This dynamic adaptation allows the system to maintain linearity during envelope transitions while maximizing efficiency during steady-state operation
Solution Approach 2:
The RF amplifier is divided into multiple amplification stages (first RF amplifier and second RF amplifier) that can operate independently or in combination. This segmentation allows different parts of the signal envelope to be amplified by different stages, with the first amplifier handling high-power segments and the second amplifier handling low-power segments, thereby maintaining both efficiency and linearity across the full power range
Data Source
AI summary
An envelope stacking power amplifier system reduces current for a given output power level without sacrificing the ability to support large voltage swings at saturation and therefore increases efficiency at the maximum linear operating power and all power levels below that. The system includes a stack/unstack controller including circuitry configured to switch the RF power amplifier system between a stacked mode in which first and second RF amplifiers are coupled in a stacked configuration and an unstacked mode in which the first and second RF amplifiers are coupled in an unstacked configuration in response to one or more mode-control signals, the stacked configuration providing reduced current compared to the unstacked configuration.