Envelope-Tracking Predistortion for Consistent PA Gain
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing digital predistortion systems based on envelope tracking are complex and costly, requiring table searchers or complex fitting polynomials, which complicates the structure and reduces the accuracy of the digital predistorter in achieving a consistent gain across the entire work area of the power amplifier.
Innovation Solution
A digital predistortion system that uses different processing manners to generate predistortion signals within specific intervals, eliminating the need for table searchers and complex polynomials, thereby simplifying the implementation and reducing costs by segmenting the output range into intervals where constant or variable gains are applied based on the amplitude ranges of the radio frequency output signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If table searchers or complex fitting polynomials are used in digital predistortion systems, then the accuracy of achieving consistent gain across the power amplifier work area is improved, but the device complexity and implementation cost increase
Solution Approach 1:
The patent divides the power amplifier's work area into multiple segments based on output signal amplitude ranges. For each segment, a simplified predistortion model is applied rather than using complex fitting polynomials across the entire range. This segmentation approach maintains gain consistency accuracy within each segment while significantly reducing the overall computational complexity and implementation cost of the digital predistorter.
2Measurement precision
If table searchers are used in digital predistortion systems, then the gain consistency across the power amplifier work area is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces expensive table searcher implementations with computationally efficient segment-based predistortion models. Each segment uses simplified mathematical relationships that can be implemented with lower-cost hardware or software resources, reducing the overall implementation cost while maintaining the necessary gain consistency accuracy through the segmented approach.
3Reliability
If the supply voltage is kept constant to ensure linear region operation, then the ACLR performance is maintained, but the power supply efficiency decreases due to energy waste
Solution Approach 1:
The patent implements dynamic supply voltage adjustment through envelope tracking, where the supply voltage varies in real-time to match the instantaneous signal envelope. This dynamic approach allows the power amplifier to operate efficiently across different signal conditions while maintaining linear region operation and ACLR performance when needed, thereby reducing energy waste compared to constant high voltage operation.
Solution Approach 2:
The patent changes the supply voltage parameter dynamically based on the signal characteristics and operating conditions. By adjusting the supply voltage to match the required output signal amplitude, the system maintains the necessary headroom for linear operation and ACLR performance while minimizing energy consumption during low-signal conditions, thus improving overall power supply efficiency.
Data Source
AI summary
Embodiments of the present disclosure a digital predistortion system and method based on envelope tracking, and a radio frequency system, so as to reduce complexity of the digital predistortion system based on envelope tracking. The system includes: a digital predistorter, a digital-to-analog converter, a frequency mixer, a power amplifier, and a power supply apparatus; where a value range of a predistortion signal that is obtained when the digital predistorter uses a first processing manner is within a first interval, and in this case, a value of a supply voltage generated by the power supply apparatus is a constant; a value range of the predistortion signal that is obtained when the digital predistorter uses a second processing manner is within a second interval, and in this case, a change of the supply voltage generated by the power supply apparatus tracks a change of an envelope signal of the predistortion signal.