Doherty Power Amplifier Phase Alignment Under Envelope Tracking
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Solution Overview
Problem
Existing high-efficiency power amplifier technologies, such as those based on conventional ET and Doherty ET power amplifiers, suffer from poor performance and efficiency due to limitations in peak-to-average ratio handling and phase asymmetry, leading to reduced power added efficiency and saturation power constraints.
Innovation Solution
A power amplifier control method and apparatus that includes an envelope control circuit and a Doherty power amplifier circuit, where phase modulation is performed on the main and auxiliary power amplifier links to optimize the phase difference based on the envelope signal, ensuring optimal phase alignment at varying envelope voltages, thereby enhancing efficiency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If power back-off is used to amplify signals with high peak-to-average ratio, then linearity is improved, but efficiency decreases sharply
Solution Approach 1:
The power amplifier is segmented into a main power amplifier and an auxiliary power amplifier. The main PA handles average power with high efficiency, while the auxiliary PA handles peak power bursts. This segmentation allows the system to maintain high linearity during peak signals without sacrificing overall efficiency, as each amplifier operates in its optimal region.
Solution Approach 2:
The system dynamically switches between different amplifier configurations based on signal conditions. During peak signals, the auxiliary PA is activated to provide additional power and maintain linearity. During average signals, only the main PA operates, maximizing efficiency. This dynamic adaptation resolves the contradiction between maintaining linearity and preserving efficiency.
2Power
If high voltage is configured for the auxiliary power amplifier to increase saturation power, then power capability is improved, but breakdown voltage constraints limit further increase
Solution Approach 1:
The power amplifier system is divided into main and auxiliary components, each with optimized voltage ratings. The auxiliary PA can be designed with appropriate voltage handling capacity without requiring excessive voltage that would approach breakdown limits. This segmentation allows the system to achieve high saturation power through coordinated operation rather than relying on a single high-voltage amplifier.
Solution Approach 2:
The system combines multiple power amplifier units with different voltage and power characteristics to create a composite power amplification system. This allows the overall system to achieve high saturation power while each individual component operates within safe voltage margins, avoiding breakdown constraints.
3Loss of energy
If asymmetric Doherty configuration is used to improve back-off efficiency, then efficiency is improved, but phase asymmetry causes performance degradation
Solution Approach 1:
The system incorporates feedback mechanisms to monitor and adjust phase relationships between the main and auxiliary power amplifiers. By detecting phase deviations caused by asymmetric configuration, the system can dynamically compensate to maintain optimal phase alignment, thus preserving signal quality while benefiting from improved back-off efficiency.
Solution Approach 2:
The system dynamically adjusts operating parameters including phase shifts and voltage levels to optimize performance. By changing these parameters in real-time based on signal conditions, the system maintains phase coherence between amplifiers while operating in the asymmetric configuration that provides superior back-off efficiency.
Data Source
AI summary
A power amplifier control method is disclosed. A phase modulation control signal may be generated according to an envelope signal that is output by a baseband unit. The phase modulation may be performed on a signal of a main power amplifier link and/or an auxiliary power amplifier link in the Doherty power amplifier circuit according to the phase modulation control signal, so that a phase difference between the signal of the main power amplifier link and the signal of the auxiliary power amplifier link after the phase modulation is a specified value corresponding to a current value of the envelope signal, where the specified value is an optimal phase value of a Doherty power amplifier circuit when the supply voltage of the Doherty power amplifier circuit is an envelope voltage corresponding to the current value of the envelope signal. High-efficiency power amplifier technology is realized.