Envelope Tracking Power Amplifier Control for Linearity and Low Dissipation
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Solution Overview
Problem
Existing amplifiers operating in envelope tracking mode face inefficiencies due to the need for high supply voltages to accommodate peak RF signal levels, leading to wasted power as heat, and struggle with maintaining linearity and reducing distortion.
Innovation Solution
A system and method that dynamically adjusts the supply power based on the envelope of the RF signal, using a control circuit to generate control signals that correlate with the envelope signal, and includes a filter to attenuate undesired coupling between amplifiers, thereby reducing oscillation and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high supply voltages are used to accommodate peak RF signal levels, then the amplifier can handle peak signals, but power is wasted as heat
Solution Approach 1:
The patent applies dynamics by transitioning from fixed supply voltage to dynamic supply voltage that tracks the envelope of the RF signal. The ETPS continuously adjusts the supply voltage to match the instantaneous envelope level, ensuring the amplifier receives only the necessary voltage at each moment, thereby eliminating wasted power while maintaining peak signal handling capability
Solution Approach 2:
The patent changes the supply voltage parameter from constant to time-varying. By making the supply voltage a dynamic parameter that follows the envelope signal, the system adapts the power delivery to match actual signal requirements, resolving the contradiction between maintaining peak power capability and reducing average power dissipation
2Loss of energy
If dynamic bias adjustment is applied to improve efficiency, then power efficiency increases, but maintaining linearity becomes more difficult
Solution Approach 1:
The patent implements feedback by using the envelope detector to continuously monitor the RF signal envelope and feed this information back to the ETPS. This closed-loop feedback mechanism allows the supply voltage to automatically adjust in response to signal variations, maintaining both efficiency and linearity through real-time adaptation
Solution Approach 2:
The envelope detector serves as an intermediary that bridges the RF signal and the ETPS control mechanism. By extracting and processing the envelope information, this intermediary enables precise coordination between the signal characteristics and supply voltage adjustments, resolving the tension between efficiency gains and linearity maintenance
3Loss of energy
If envelope tracking is implemented to shift linearity burden to ETPS, then amplifier efficiency improves, but system complexity increases
Solution Approach 1:
The patent applies segmentation by separating the linearity function from the power amplification function. The amplifier focuses on power delivery while the ETPS handles linearity maintenance through envelope tracking. This functional segmentation allows each component to optimize its performance without bearing the full system complexity
Solution Approach 2:
The ETPS performs multiple functions: it provides power supply, implements envelope tracking, maintains linearity, and adjusts bias dynamically. By consolidating these functions into a single multi-functional unit, the patent reduces overall system complexity despite the advanced capabilities required
Data Source
AI summary
Control systems and methods for power amplifiers operating in envelope tracking mode are presented. A set of corresponding functions and modules are described and various possible system configurations using such functions and modules are presented.