Power Amplifier Feedback Control for Impedance Mismatch Compensation
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Solution Overview
Problem
Conventional systems face challenges in accurately synchronizing the radio frequency (RF) envelope with the power amplifier (PA) supply voltage due to impedance mismatches between the PA and filters, leading to performance degradation and distortion issues, particularly in envelope tracking applications.
Innovation Solution
A system that measures the output signal of the PA between the PA and the filter, allowing for real-time adjustment of the PA stimuli, including the supply voltage and RF signal, to optimize the delay of the envelope tracking path and compensate for impedance mismatches, thereby ensuring precise synchronization and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If envelope tracking is used to reduce battery current, then power efficiency is improved, but synchronization between RF envelope and PA supply voltage deteriorates due to impedance mismatches
Solution Approach 1:
The patent implements a feedback mechanism where the output signal of the power amplifier is measured and used to adjust the ET path delay dynamically. This closed-loop approach compensates for impedance mismatch effects by continuously monitoring the actual output and correcting the synchronization delay, thereby maintaining reliable synchronization while preserving the energy efficiency benefits of envelope tracking
Solution Approach 2:
The patent dynamically adjusts the delay parameter of the envelope tracking path based on measured output signal characteristics. By changing the delay parameter in response to operating conditions and impedance mismatches, the system maintains optimal synchronization between the RF envelope and PA supply voltage across varying power levels and load conditions
2Measurement precision
If real-time adjustment of PA stimuli is implemented, then synchronization precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-adjustment by measuring its own output signal and automatically correcting the ET path delay without requiring external intervention or complex control systems. The power amplifier's output is fed back to adjust its own operating parameters, simplifying the overall control architecture while achieving high synchronization precision
Solution Approach 2:
The output signal measurement serves multiple functions: it provides feedback for delay adjustment, enables distortion compensation, and supports performance monitoring. This multi-functional use of the measurement mechanism reduces the need for separate dedicated components, thereby limiting the increase in device complexity while achieving precise synchronization
Data Source
AI summary
Compensation for one or more effects of impedance mismatch between a power amplifier (PA) and at least one filter is discussed. One example system that compensates for impedance mismatch with at least one filter comprises a PA, a measurement component, and a feedback component. The PA is configured to receive PA stimuli comprising a supply voltage and a radio frequency (RF) signal to be amplified, wherein a PA output is configured to be coupled to the at least one filter. The measurement component is coupled to the PA and configured to measure an output signal from the PA, wherein the output signal comprises a forward signal associated with the PA and a reflected signal associated with the at least one filter. The feedback component is configured to receive the output signal and to adjust one or more of the PA stimuli based at least in part on the output signal.