Asymmetric Outphasing RF Amplifier With Power-Recycling Combiner
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Solution Overview
Problem
Conventional RF transmitter architectures face challenges in achieving high efficiency and linearity, particularly for high data-rate communication standards like WiMAX, due to inefficiencies in power amplifiers and combiners, leading to wasted energy and signal distortion.
Innovation Solution
The asymmetric multilevel outphasing (AMO) transmitter architecture uses a switch network to supply discrete voltages to power amplifiers and incorporates a resistance compression network (RCN) to recover wasted power, maintaining high linearity and efficiency across a wide power range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional polar architecture is used to improve power amplifier efficiency, then efficiency is improved, but bandwidth is limited and converter efficiency degrades dramatically as bandwidth increases
Solution Approach 1:
The invention divides the signal amplification task into multiple parallel paths (in-phase and quadrature components), each handled by separate power amplifiers operating at reduced power levels. This segmentation allows the system to achieve high efficiency while maintaining wide bandwidth capability, as each amplifier operates in a more efficient region without requiring a single high-bandwidth power converter.
Solution Approach 2:
The patent transitions from conventional polar coordinate representation to Cartesian coordinate representation for signal decomposition. By using in-phase (I) and quadrature (Q) components instead of amplitude and phase components, the system avoids the bandwidth expansion problem inherent in polar conversion while maintaining the ability to control power amplifier operation for high efficiency.
2Adaptability or versatility
If conventional LINC architecture with isolating combiner is used to eliminate high-bandwidth power converter, then bandwidth is improved, but power is wasted as heat in the isolation resistor
Solution Approach 1:
The invention converts the harmful effect of the isolating combiner by replacing the passive isolation resistor with an active power recycling mechanism. The power that would be wasted as heat is instead captured and fed back to the power supply, transforming energy loss into useful power recovery and significantly improving overall system efficiency.
Solution Approach 2:
The patent implements power recovery by capturing the power dissipated in the isolating combiner through a power recycling circuit. This recovered power is then fed back to the power supply, effectively recovering energy that would otherwise be discarded as heat and improving the system's overall energy efficiency.
3Productivity
If high PAPR modulation schemes are used to achieve high data rates, then data rate is improved, but average efficiency decreases due to inverse proportionality with PAPR
Solution Approach 1:
The invention dynamically adjusts the operating points of multiple power amplifiers based on the instantaneous signal requirements. By continuously optimizing the power distribution among parallel amplifiers and implementing power recycling, the system maintains high efficiency across varying power conditions, thereby improving average efficiency even when using high PAPR modulation schemes for high data rates.
Data Source
AI summary
A radio frequency (RF) circuit includes a power supply configured to generate a plurality of voltages, a plurality of power amplifiers, each having an RF output port and a power supply input port, a switch network having a plurality of input ports coupled to the power supply and a plurality of switch network output ports coupled to the power supply input ports of the plurality of power amplifiers, wherein the switch network is configured to output selected ones of the plurality of voltages from the plurality of switch network output ports, at least two of the switch network output port voltages capable of being different ones of the plurality of voltages, and an RF power combiner circuit having a plurality of input ports coupled to RF output ports of the plurality of power amplifiers and an output port at which is provided an output signal of the RF circuit.