Power Amplifier Chain Linearization with Digital Predistortion
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Solution Overview
Problem
Existing power amplifier systems face inefficiencies in power efficiency and linearity due to the operation of pre-driver and driver chains in linear regions, leading to increased output distortion when driven into mild/high non-linearity for improved efficiency.
Innovation Solution
A system and method utilizing cascaded drivers prefixed to the power amplifier, employing digital predistortion techniques to generate a predistorted signal, monitor output signals, and adjust inverse coefficients to achieve linearized power output through the power amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pre-driver and driver chain is operated in a linear region, then the output distortion is reduced, but the power efficiency is reduced
Solution Approach 1:
The patent applies digital predistortion to pre-compensate for the non-linearities of the power amplifier chain. By calculating and applying the inverse distortion characteristics in advance, the system enables the driver chain to operate in a more efficient non-linear region while ensuring the overall output remains linear and free from distortion.
Solution Approach 2:
The patent implements a feedback mechanism where the actual output of the power amplifier chain is monitored and compared with the expected linear output. The distortion characteristics are continuously measured and used to update the predistortion coefficients, allowing the system to adapt to changing conditions and maintain optimal performance.
2Loss of energy
If the pre-driver and driver chain is driven into mild/high non-linearity for improved efficiency, then the power efficiency is improved, but the output distortion increases
Solution Approach 1:
The system pre-calculates the distortion characteristics of the power amplifier chain and stores them in a lookup table. During operation, the inverse distortion is applied in advance to the input signal, allowing the driver chain to operate in a highly efficient non-linear region while the overall system output remains linear.
Solution Approach 2:
The patent dynamically adjusts the predistortion coefficients based on operating conditions such as input power level, temperature, and load impedance. By changing these parameters in real-time, the system maintains optimal power efficiency while compensating for distortion across varying operating scenarios.
3Object-generated harmful factors
If a linear input is provided to the power amplifier, then the output distortion is minimized, but the power efficiency of the pre-driver and driver chain is reduced
Solution Approach 1:
Instead of operating the driver chain linearly, the system pre-distorts the input signal to compensate for the upcoming non-linear power amplifier. This allows the driver chain to operate in a more efficient non-linear region, and the pre-distortion ensures that the overall output remains linear, thereby improving power efficiency without sacrificing distortion performance.
4Object-generated harmful factors
If digital predistortion is applied to linearize the power amplifier, then the output linearity is improved, but the hardware complexity and power consumption increase
Solution Approach 1:
The patent uses a lookup table approach where pre-computed distortion characteristics are stored and retrieved during operation. Instead of using complex real-time mathematical models, the system uses a simplified table-based approach that reduces computational complexity while maintaining effective linearization performance.
Data Source
AI summary
The present disclosure provides a system and a method for linearization of a power amplifier chain. The system determines a predistorted signal associated with a coupled power output of a power amplifier along a first transmission path among one or more transmission paths based on a RF input signal received by the transceiver. The system determines, an output signal associated with the coupled power output of the PA along a second transmission path among the one or more transmission paths, where the coupled power output is based on the predistorted signal. The system monitors, the output signal associated with the PA. The system varies the predistorted signal to generate the power output through the PA.