Uneven Power Splitter for Flat Power Amplifier Linearization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power amplifier combined topologies, such as the Doherty PA, face challenges in achieving flat AM-AM and AM-PM performance due to asymmetrical power amplifiers, which are not efficiently linearized and are not compatible with mmWave large scale arrays or wide bandwidths.
Innovation Solution
The implementation of a power amplifier circuit using an uneven power splitter that feeds two power amplifiers of different classes, such as a class B and a class C amplifier, allowing for controlled power distribution and phase compensation to achieve a flat performance curve over a wide range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If asymmetrical power amplifiers are used in power combined topology to enhance efficiency under backoff, then power efficiency is improved, but AM-AM and AM-PM performance becomes non-flat
Solution Approach 1:
The patent applies digital pre-distortion (DPD) to pre-compensate the input signals before they reach the asymmetrical power amplifiers. By calculating and applying inverse distortion characteristics in advance, the system counteracts the non-linear effects that would otherwise degrade AM-AM and AM-PM performance, enabling both high efficiency and flat performance characteristics.
Solution Approach 2:
The patent implements feedback mechanisms where the output signals from the power combined amplifiers are monitored and fed back to adjust the pre-distortion parameters. This closed-loop approach allows the system to dynamically compensate for variations in amplifier characteristics and maintain flat AM-AM and AM-PM performance across different operating conditions while preserving the efficiency benefits of asymmetrical amplifiers.
2Manufacturing precision
If conventional linearization methods (APD or DPD) are applied to power combined PAs, then AM-AM and AM-PM performance is improved, but efficiency is sacrificed
Solution Approach 1:
The patent optimizes the pre-distortion approach by carefully designing the pre-distortion function to compensate only for the necessary non-linearities while minimizing additional power consumption. The system calculates pre-distortion parameters based on characterized amplifier models, applying corrections in advance rather than requiring power-intensive real-time iterative correction, thus maintaining efficiency while achieving linearization.
Solution Approach 2:
The patent adjusts key parameters including the power split ratio between asymmetrical amplifiers and the pre-distortion function characteristics to optimize the trade-off between efficiency and linearization performance. By carefully selecting amplifier classes and their respective power distribution, along with tuning pre-distortion parameters, the system achieves both efficiency improvement and acceptable AM-AM/AM-PM flatness without excessive power consumption.
3Use of energy by moving object
If asymmetrical power amplifiers with different performance curves are used, then efficiency under backoff is enhanced, but overall combined amplifier performance becomes non-uniform
Solution Approach 1:
The patent applies pre-distortion processing to the input signals before they are distributed to the asymmetrical power amplifiers. By pre-compensating for the different performance curves of the asymmetrical amplifiers, the system ensures that their combined output achieves uniform performance characteristics across the operating range, while still benefiting from the efficiency advantages of using asymmetrical amplifier configurations.
Data Source
AI summary
Methods and apparatus for implementing a power amplifier circuit assembly an uneven power splitter which feeds two power amplifiers of different amplifier classes are described. By supplying different amounts of power to different amplifier circuits having different performance curves, an overall combined amplifier performance having a relatively uniform, e.g., flat, performance curve over a wide range of frequencies is achieved. In at least some embodiments one of the amplifiers is a class B power amplifier and the other amplifier is a class C power amplifier. In some but not necessarily all embodiments a phase shift is introduced on a signal path to one of the power amplifiers to compensate for a difference in phase shifts introduced by the power amplifiers which are used in parallel.