RF Power Amplifier Envelope Tracking With Variable Compression
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Solution Overview
Problem
Wireless communication devices require RF circuitry that is low cost, small, simple, and efficient while meeting performance requirements such as specific out-of-band emissions and linearity, with the need to balance efficiency and spectrum degradation in RF power amplifiers.
Innovation Solution
The RF transmitter circuitry employs an envelope tracking power supply and RF power amplifier that operates in multiple modes based on compression tolerance criteria, switching between first and second compression levels to optimize efficiency and manage spectrum degradation, with the selection of operating modes determined by duplex frequency and envelope power supply signal bandwidth thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the RF power amplifier operates at higher compression levels to increase efficiency, then energy efficiency is improved, but spectrum degradation increases
Solution Approach 1:
The system dynamically switches between two operating modes (first mode with lower compression level and second mode with higher compression level) based on duplex frequency conditions. The mode selection is controlled by comparing the duplex frequency to a threshold value, allowing the RF power amplifier to adapt its compression level and efficiency characteristics according to the specific communication scenario, thereby resolving the contradiction between efficiency and spectrum degradation
Solution Approach 2:
The invention changes the operating parameter (compression level) of the RF power amplifier based on the duplex frequency. By selecting different compression levels (first compression level in first mode, second compression level in second mode) according to whether the duplex frequency is below or above the threshold, the system optimizes the balance between efficiency and spectrum degradation for different operating conditions
2Loss of energy
If envelope tracking power supply bandwidth is increased to improve tracking accuracy, then efficiency optimization is improved, but device complexity increases
Solution Approach 1:
The system segments the operating conditions based on duplex frequency thresholds and assigns different compression levels to different segments. By dividing the operation into discrete modes (first mode for duplex frequency below threshold, second mode for duplex frequency above threshold), the system achieves efficient envelope tracking without requiring a continuously variable high-bandwidth power supply, thus reducing complexity while maintaining effectiveness
Solution Approach 2:
The mode selection mechanism dynamically adjusts the compression level based on real-time duplex frequency measurements. This dynamic adaptation allows the system to achieve efficient envelope tracking performance when needed (when duplex frequency exceeds threshold) while avoiding unnecessary complexity in operating conditions where high tracking accuracy is not required
Data Source
AI summary
Radio frequency (RF) transmitter circuitry, which includes an envelope tracking power supply and an RF power amplifier (PA), is disclosed. The RF PA operates in either a first operating mode or a second operating mode, such that selection of the operating mode is based on compression tolerance criteria. During the first operating mode, the RF PA receives and amplifies an RF input signal using a first compression level. During the second operating mode, the RF PA receives and amplifies the RF input signal using a second compression level, which is greater than the first compression level. The envelope tracking power supply provides an envelope power supply signal to the RF PA. The envelope power supply signal provides power for amplification.