Multilevel RF Power Amplification With State-Based Predistortion
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Solution Overview
Problem
Achieving high efficiency and high linearity in radio frequency (RF) power amplifier systems is challenging due to the difficulty in managing discrete transitions among operating states and the introduction of unwanted components during power supply voltage changes, which affect the output spectrum.
Innovation Solution
Implementing a system with State-Based Digital Pre-Distortion (SB-DPD) and pulse cancellation techniques, where the power supply voltage is dynamically selected from multiple levels based on signal characteristics, and compensation signals are introduced to mitigate disturbances caused by state changes, ensuring high-linearity and efficient operation across different states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage is dynamically switched among multiple discrete levels to improve efficiency, then energy efficiency is improved, but unwanted components are introduced into the output spectrum during transitions
Solution Approach 1:
The patent applies preliminary action by predistorting the input signal before it reaches the power amplifier. The predistortion is specifically tailored to compensate for the unwanted components that will be generated during power supply voltage transitions. By pre-applying the corrective distortion to the input signal, the system proactively cancels out the harmful spectral components before they are generated, thus resolving the contradiction between efficiency improvement and unwanted output components.
2Use of energy by moving object
If discrete transitions among operating states are used to improve efficiency, then power efficiency is improved, but linearity deteriorates due to abrupt state changes
Solution Approach 1:
The predistortion technique performs preliminary action by pre-compensating the input signal for the non-linear effects that will occur during discrete state transitions. The predistorter applies corrective transformations to the input signal in advance, ensuring that after the power amplifier's non-linear distortion and abrupt state changes, the output remains linear and faithful to the original input signal.
Solution Approach 2:
The patent employs feedback mechanisms to monitor the actual output signal and use this information to adjust the predistortion parameters. By continuously measuring the output and comparing it to the desired linear response, the system can adaptively refine the predistortion correction, thereby maintaining linearity despite the discrete transitions among operating states.
3Manufacturing precision
If continuous envelope tracking is used to maintain linearity, then output signal linearity is improved, but power efficiency deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the continuous envelope tracking approach into discrete operating states. Instead of continuously adjusting the power supply voltage, the system segments the operation into distinct voltage levels and transitions between them. This segmentation maintains linearity through the predistortion technique while improving efficiency by allowing the amplifier to operate in well-defined states rather than continuously varying, thus reducing the efficiency penalty of continuous envelope tracking.
Data Source
AI summary
Circuits and methods for performing multilevel power amplification using multiple different supply voltages or states are disclosed. In some embodiments, power amplifiers are provided that switch between three or more supply voltages or states.