Envelope Tracking Transfer Function Recalibration During Transmission
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Solution Overview
Problem
Envelope tracking power amplifiers face inefficiencies due to constant supply voltage, leading to increased battery current consumption, especially in LTE signals, and require recalibration to account for antenna impedance changes and aging effects, which existing methods fail to address effectively.
Innovation Solution
An envelope tracking system that adjusts the nonlinear transfer function of the power supply using a feedback receiver to determine the difference between assumed and actual performance, allowing for real-time recalibration and optimization of parameters such as offset, gain, and transfer function shape to maintain peak efficiency and battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant supply voltage is applied to power amplifier, then device complexity is reduced, but power efficiency deteriorates and battery current consumption increases
Solution Approach 1:
The patent implements dynamic supply voltage adjustment by continuously varying the DC supply voltage to the power amplifier according to the instantaneous envelope of the RF signal. This dynamic control enables the power amplifier to operate at peak efficiency across different output power levels, resolving the contradiction between constant voltage simplicity and variable voltage efficiency.
Solution Approach 2:
The patent employs feedback mechanisms where the instantaneous envelope of the RF signal is detected and used to control the DC-DC converter output voltage. This closed-loop feedback ensures the supply voltage dynamically tracks the signal envelope, maintaining optimal efficiency while managing battery current consumption.
2Use of energy by moving object
If envelope tracking is implemented with variable supply voltage, then power efficiency is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent combines the envelope detection function with the DC-DC converter control function into an integrated system. The DC-DC converter is designed to directly accept the RF signal and generate the appropriate supply voltage through its switching mechanism, merging multiple functions into a single integrated block to reduce overall system complexity.
Solution Approach 2:
The DC-DC converter is designed to perform multiple functions: it acts as both the power supply for the power amplifier and the envelope tracker. By making the DC-DC converter universal, the patent eliminates the need for separate envelope detection and voltage control circuits, thereby reducing device complexity while maintaining high efficiency.
3Device complexity
If fixed transfer function is used in envelope tracker, then device complexity is reduced, but adaptability to impedance changes and aging effects deteriorates
Solution Approach 1:
The patent implements self-calibration functionality where the system automatically adjusts the transfer function parameters based on measured performance deviations. The envelope tracker monitors its own operation and performs recalibration without external intervention, enabling the system to adapt to impedance changes and aging effects while maintaining relatively simple hardware architecture.
Data Source
AI summary
An envelope tracking system and a method for adjusting a nonlinear transfer function of an envelope tracking power supply for a power amplifier are provided. An output signal of the power amplifier is provided to a feedback receiver for determining an actual performance of the envelope tracking power amplifier. An assumed performance of the envelope tracking power amplifier is determined by evaluating the non-linear transfer function at a value defined by an input signal for a transmitter including the power amplifier. A difference between the assumed performance and the actual performance provides a correctional value for the nonlinear transfer function.