Envelope-Stacking RF Power Amplifier for High-PAPR 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 due to voltage and current clipping, which increases heat dissipation and reduces battery life in wireless devices.
Innovation Solution
An RF power amplifier system with a stack/unstack controller dynamically switches between stacked and unstacked configurations of two RF amplifiers to maintain linearity and reduce current consumption, sharing or not sharing DC current based on input signals, and using a power combiner to combine RF outputs, thereby optimizing 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 each stage to operate in its optimal region while maintaining overall system linearity and efficiency.
Solution Approach 2:
The invention dynamically switches between different amplifier configurations (stacked and unstacked) based on the input signal characteristics. The switching configuration adapts the amplifier operation mode in real-time to maintain linearity for high PAPR signals while maximizing efficiency when possible.
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 invention merges the output of multiple RF amplifiers (first and second RF amplifiers) to achieve the desired output power level. By combining multiple amplifiers operating at lower individual power levels, the system maintains linearity while achieving the required total output power, thus avoiding the efficiency penalty of single-amplifier back-off operation.
Solution Approach 2:
The system dynamically selects between stacked and unstacked configurations based on signal conditions. When high linearity is required, the system uses the stacked configuration with multiple amplifiers working together. When signal conditions allow, it switches to unstacked configuration to improve efficiency.
3Quantity of substance
If multiple RF amplifiers are used in stacked configuration to reduce current, then current consumption is reduced, but device complexity increases
Solution Approach 1:
The invention uses a dynamic switching mechanism that automatically selects between stacked and unstacked amplifier configurations based on real-time signal characteristics. This dynamic approach manages the complexity of multiple amplifier configurations by automating the selection process, making the system adaptable without requiring manual intervention or overly complex control logic.
Solution Approach 2:
The system changes operational parameters (configuration mode) based on input signal characteristics such as PAPR. By monitoring signal parameters and adapting the amplifier configuration accordingly, the system optimizes current consumption while managing complexity through parameter-based control rather than structural complexity.
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.