Envelope-Tracking Power Amplifier Control Across Wide Dynamic Range
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Solution Overview
Problem
Existing envelope tracking power supply systems for radio transmitters in mobile communication systems are inefficient at managing high power control ranges, particularly in achieving accurate voltage tracking across a wide dynamic range required for applications like 3GPP WCDMA transmitters.
Innovation Solution
The implementation of an amplification stage with an input scaling block, power amplifier, envelope detector, envelope scaling block, non-linear mapping block, modulator, and power control block that maintains a linear relationship between envelope and input scaling factors, allowing for efficient power supply voltage generation and distribution across multiple variable gain stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope tracking power supply systems are used for radio transmitters, then power amplification efficiency is improved, but the system cannot efficiently manage high power control ranges across wide dynamic range
Solution Approach 1:
The power control function is segmented into multiple independent scaling blocks: an input scaling block that scales the input signal, an envelope scaling block that scales the envelope signal, and a power control block that generates scaling factors. This segmentation allows each block to handle specific portions of the power control range, enabling the system to efficiently manage wide dynamic ranges while maintaining high power amplification efficiency through envelope tracking.
2Use of energy by moving object
If the supply voltage tracks the instantaneous RF envelope with high accuracy, then power amplification efficiency is improved, but the system complexity increases due to non-linear mapping and multiple scaling blocks
Solution Approach 1:
The system performs preliminary scaling of both the input signal and envelope signal before they reach the power amplifier. The input scaling block pre-scales the input signal, and the envelope scaling block pre-scales the envelope signal using scaling factors generated by the power control block. This preliminary action simplifies the requirements for non-linear mapping and reduces the complexity of real-time voltage tracking while maintaining high power amplification efficiency.
3Measurement precision
If a linear relationship is maintained between envelope scaling factor and input scaling factor, then power control accuracy is improved, but additional control mechanisms are required
Solution Approach 1:
The power control block generates the envelope scaling factor and input scaling factor in a coordinated manner to maintain a linear relationship between them. This feedback mechanism ensures that as the input signal power changes, the envelope scaling adjusts proportionally, maintaining accurate power control across the dynamic range. The linear relationship ensures power control accuracy while the coordinated generation of scaling factors manages the control mechanism complexity.
Data Source
AI summary
An amplification stage comprising: an input scaling block for scaling an input signal based on an input scaling factor to generate a scaled version of the input signal; a power amplifier for receiving the scaled version of the input signal and for generating an amplified version of said signal; an envelope detector for generating a signal representing the envelope of the input signal; an envelope scaling block for scaling the envelope signal based on an envelope scaling factor to generate a scaled version of the envelope signal; a non-linear mapping block for generating a voltage representative of the supply voltage based on the scaled envelope signal; a modulator for generating a power supply voltage for the amplifier based on the voltage generated by the non-linear mapping block; and a power control block for maintaining a linear relationship between the envelope scaling factor and the input scaling factor.