Segmented RF Power Amplifier Linearization Under Power Back-Off
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Solution Overview
Problem
Conventional RF power amplifiers face challenges in achieving high efficiency and linearity, especially under power back-off conditions, leading to reduced efficiency and increased power consumption, which is exacerbated by high Peak to Average Power Ratio (PAPR) in modern wireless communication systems.
Innovation Solution
A distributed variable power amplifier design featuring parallel cells with segmented transistors and a control circuit that selectively switches on or off transistor banks to adjust output power levels, utilizing Composite Right/Left Handed (CRLH) transmission lines and matching networks to maintain linear operation and optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional RF power amplifiers operate under power back-off conditions to meet linearity requirements, then linearity is improved, but efficiency deteriorates
Solution Approach 1:
The power amplifier is divided into multiple parallel cells, each containing segmented transistor banks that can be independently controlled. This segmentation allows the amplifier to operate different sections at optimal points depending on signal conditions, maintaining efficiency while meeting linearity requirements through selective activation of transistor banks based on detected RF signal levels
Solution Approach 2:
The amplifier employs dynamic control of transistor banks through a control circuit that detects RF signal characteristics and adjusts the operating state of individual transistor banks in real-time. This dynamic adaptation allows the system to transition between high-efficiency modes during low-power intervals and high-linearity modes during peak power intervals, resolving the contradiction between efficiency and linearity
2Use of energy by moving object
If distributed amplifier stages are increased to maintain efficiency at reduced output power, then efficiency is improved, but device complexity increases
Solution Approach 1:
Instead of increasing the number of distributed amplifier stages, the invention segments the existing stages into multiple parallel cells with independently controllable transistor banks. This approach maintains efficiency through selective activation rather than through cascaded stages, avoiding the complexity increase that would result from adding more distributed stages while still achieving the goal of maintaining efficiency at reduced output power
3Use of energy by moving object
If transistor banks are selectively switched to vary output power level, then power consumption is reduced, but maintaining linear operation becomes more difficult
Solution Approach 1:
A control circuit with RF signal detection capability provides feedback control over the transistor banks. The detector monitors the RF signal characteristics and the control circuit adjusts the switching state of transistor banks accordingly, ensuring that linear operation is maintained even as output power varies. This feedback mechanism coordinates the power-saving switching actions with linearity requirements, allowing the system to reduce power consumption without sacrificing linear operation
Data Source
AI summary
Designs and techniques associated with power amplifiers for amplifying RF signals to provide variable power amplification and improved linearity in various RF amplification circuits, including power amplifiers operated under the power back-off conditions.