RF Amplifier Transition Shaping for Efficient Linear Transmission
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Solution Overview
Problem
RF transmitters typically face a trade-off between energy efficiency and linearity, where achieving high efficiency often comes at the cost of reduced linearity and vice versa, making it difficult to simultaneously attain both in RF amplifiers and transmitters.
Innovation Solution
The implementation of a digital control system that manages the amplitudes and phases of RF input signals and supply voltages to RF power amplifiers, using non-linear power amplifiers and discrete voltage levels to achieve high efficiency and linearity through dynamic voltage selection and switching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-linear power amplifiers are used to achieve high efficiency, then energy efficiency is improved, but linearity deteriorates
Solution Approach 1:
The patent applies dynamics by making the supply voltage to the power amplifier dynamically adjustable across multiple discrete levels. The voltage control unit switches between different voltage levels (V1, V2, V3, V4) based on the instantaneous signal conditions, allowing the amplifier to operate in different efficiency modes while maintaining linearity when needed. This dynamic voltage adjustment resolves the contradiction by enabling the system to adapt between high-efficiency and high-linearity operation states.
Solution Approach 2:
The patent changes the supply voltage parameter of the power amplifier to resolve the efficiency-linearity tradeoff. By providing multiple discrete voltage levels to the amplifier, the system can adjust the operating point of the amplifier dynamically. Higher voltage levels enable linear operation with lower efficiency, while lower voltage levels achieve higher efficiency with reduced linearity capability, allowing optimal parameter selection based on signal requirements.
2Use of energy by moving object
If discrete voltage levels are switched dynamically to achieve high efficiency, then energy efficiency is improved, but signal linearity deteriorates due to voltage transitions
Solution Approach 1:
The patent applies preliminary action by using a transition shaping filter before the voltage switch to pre-condition the supply voltage transitions. The filter shapes the voltage edges to be smoother and extends the transition time, preventing abrupt voltage changes that would cause spectral regrowth and signal distortion. This preliminary filtering action ensures that when voltage levels are switched for efficiency, the signal linearity is preserved by eliminating harmful transition artifacts.
Solution Approach 2:
The transition shaping filter acts as an intermediary between the voltage switch and the power amplifier. It mediates the voltage transitions by smoothing them out, preventing direct coupling of abrupt voltage changes to the amplifier. This intermediary filter protects the signal linearity while allowing efficient voltage switching to occur, resolving the contradiction between efficiency switching and signal integrity.
3Use of energy by moving object
If multiple discrete voltage levels are provided to the power amplifier, then efficiency control is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the voltage control function into discrete, manageable voltage levels (V1, V2, V3, V4) that can be independently selected. Each voltage level corresponds to a specific efficiency mode, and the control system segments the voltage selection into distinct states rather than requiring continuous control. This segmentation simplifies the control logic while providing efficient multi-level voltage operation.
Solution Approach 2:
The patent merges multiple voltage levels into a single power amplifier supply input, allowing one amplifier to operate at different efficiency points by changing its supply voltage. Instead of using multiple separate amplifiers for different power levels, the system combines the functionality into a single amplifier with dynamically adjustable supply voltage, reducing overall system complexity while maintaining efficiency control capabilities.
Data Source
AI summary
A radio frequency (RF) power amplifier system or transmitter includes one or more power amplifiers and a controller that is configured to adjust amplitudes and phases of RF input signals of the one or more power amplifiers and supply voltages applied to the one or more power amplifiers. In embodiments where multiple power amplifiers are used, a combiner may be provided to combine outputs of the power amplifiers.