Tri-Phasing Radio Transmitter Amplification for Wideband Efficiency
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Solution Overview
Problem
Conventional linear power amplifiers are inefficient for 5G systems with high peak-to-average power ratio (PAPR) signals due to their low power efficiency, while switched-mode power amplifiers (SM-PAs) offer high efficiency but degrade quickly in power back-off, leading to signal distortion and poor efficiency in wideband outphasing transmitters.
Innovation Solution
The tri-phasing approach uses three signal components to enable continuous amplitude level transitions, combining a polar modulator with two outphasing signals to modulate the amplitude and phase of the transmission signal, avoiding signal degradation issues present in multilevel outphasing by synchronizing amplitude level transitions with the phase modulated signal and using digital interpolating phase modulators for precise interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional linear power amplifiers are used, then signal linearity is maintained, but power efficiency deteriorates with high PAPR signals
Solution Approach 1:
The transmission signal is segmented into multiple constant-envelope signals with different phases (e.g., three signals at 0°, 120°, and 240° phases). Each signal is amplified separately by efficient switched-mode power amplifiers, and the amplified signals are combined to reconstruct the original high-PAPR signal with improved linearity and efficiency.
2Loss of energy
If switched-mode power amplifiers are used, then power efficiency is improved, but signal linearity deteriorates due to non-linear operation
Solution Approach 1:
The signal is divided into multiple constant-envelope components that can be efficiently amplified by non-linear switched-mode power amplifiers. The phase diversity of these components ensures that their combined output maintains the linearity of the original signal while benefiting from the high efficiency of SM-PA operation.
Solution Approach 2:
The invention creates a composite signal structure by combining multiple phase-shifted constant-envelope signals. This composite approach allows the system to leverage the efficiency of non-linear amplifiers while maintaining overall signal fidelity through constructive interference of the phased components.
3Adaptability or versatility
If outphasing transmitters are used, then bandwidth is increased, but efficiency deteriorates quickly in power back-off conditions
Solution Approach 1:
The outphasing signal is further segmented into multiple discrete phase components (e.g., three-phase segmentation). This allows the system to maintain efficiency in power back-off conditions by selectively activating specific phase combinations, while still supporting wide bandwidth operation through the phase diversity provided by the segmented structure.
4Loss of energy
If multilevel outphasing is used, then efficiency in power back-off is improved, but signal distortion increases
Solution Approach 1:
The signal is segmented into a specific number of discrete phase levels (e.g., three phases). This controlled segmentation provides multiple amplitude levels for efficient power back-off operation while limiting the number of transition points, thereby reducing signal distortion and maintaining better signal quality compared to finer multilevel segmentation.
Data Source
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AI summary
According to an aspect, there is provided a method for power-amplification of a transmission signal, comprising: obtaining the transmission signal with phase and amplitude modulation; generating a power-amplified polar signal for approximating a power-amplified transmission signal by power-amplifying a first constant-envelope signal with one of two or more first amplification factors based on the transmission signal; generating an outphasing pair of a first power-amplified outphasing signal and a second power-amplified outphasing signal based on the transmission signal; and combining the power-amplified polar signal, the first power-amplified outphasing signal and the second power-amplified outphasing signal to provide the power-amplified transmission signal.