Multi-Branch Outphasing Amplifier Switching for Power Back-Off Efficiency
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Solution Overview
Problem
Traditional multi-level outphasing power amplifiers face inefficiencies at large power back-off conditions due to high power consumption and difficulty in implementing multiple power supply levels, leading to reduced power efficiency and increased heat sinking costs in wireless communication systems.
Innovation Solution
A multi-level, multi-branch outphasing amplifier design that selectively turns on and off branch circuits based on control signals, eliminating the need for multiple power supply voltages and using reactive efficiency elements to reduce out-of-phase current, thereby enhancing power efficiency and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple power supply voltages are used to improve power efficiency at different power levels, then power efficiency is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The power amplifier is divided into multiple independent branch circuits (first branch circuit, second branch circuit, third branch circuit, fourth branch circuit), each capable of operating independently. This segmentation allows selective activation of branches based on power level requirements without needing multiple power supply voltages, thus improving power efficiency while avoiding the complexity of multi-voltage systems.
Solution Approach 2:
The system dynamically selects which branch circuits to activate based on the required output power level. Control signals selectively turn on or off specific branch circuits to match the instantaneous power demand, enabling efficient operation across different power levels without fixed multiple power supplies.
2Adaptability or versatility
If traditional power amplifiers operate at reduced output power levels, then adaptability to varying power demands is improved, but power efficiency deteriorates
Solution Approach 1:
By segmenting the amplifier into multiple branch circuits that can be selectively activated, the system maintains high efficiency across different power levels. Each branch contributes a specific power level, and by combining different numbers of active branches, the system adapts to varying power demands while keeping active amplifiers operating efficiently.
Solution Approach 2:
The system changes the operational parameters by varying the number of active branch circuits rather than operating a single amplifier at reduced power levels. This approach keeps active amplifiers operating at optimal points while achieving the required power adaptation through parallel branch combination.
3Ease of operation
If out-of-phase current is present in the system, then power amplifier operation is simplified, but power efficiency and linearity deteriorate
Solution Approach 1:
The system converts the potentially harmful out-of-phase current into a beneficial feature by using reactive efficiency elements that resonate at the operating frequency. These elements transform the out-of-phase current into useful reactive power circulation, improving overall efficiency while maintaining the simplicity of the outphasing architecture.
Solution Approach 2:
Reactive efficiency elements are introduced as intermediary components between the power amplifiers and the load. These elements mediate the interaction between out-of-phase currents, resonating at the operating frequency to cancel harmful effects and improve efficiency without complicating the basic outphasing operation.
Data Source
AI summary
A first branch group circuit includes a first branch circuit receiving a first RF input signal and first control information; and a second branch circuit receiving the first input signal and second control information. Each of the first and second branch circuits includes a power amplifier. The second control information enables the second branch circuit to be switched on or off while the first branch circuit remains on. A second branch group circuit includes: a third branch circuit receiving a second RF input signal and third control information; and a fourth branch circuit receiving the second input signal and fourth control information. Each of the third and fourth branch circuits includes a power amplifier. The fourth control information enables the fourth branch circuit to be switched on or off while the third branch circuit remains on. A combiner combines output signals of the power amplifiers to produce an output signal.