Pseudo-envelope Feedback Delay Compensation for Power Amplifiers
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Solution Overview
Problem
Current power management systems for mobile devices, particularly those with linear RF power amplifiers, face inefficiencies that reduce battery life due to delays in controlling switch mode power supply converters and sensing output currents, which degrade power efficiency.
Innovation Solution
A pseudo-envelope follower power management system is introduced, incorporating a switch mode power supply converter and a feedback delay compensation circuit, along with a parallel amplifier circuit, to regulate the power amplifier supply voltage efficiently by using the derivative of the VRAMP signal to adjust switching thresholds and compensate for delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switch mode power supply converter is used to regulate power amplifier supply voltage, then power efficiency is improved, but delays in controlling the converter and sensing output currents occur which degrade performance
Solution Approach 1:
The patent applies preliminary action by using the derivative of the VRAMP signal to predict future voltage requirements before they actually occur. The feedback delay compensation circuit calculates d(VRAMP)/dt and uses this information to adjust switching thresholds in advance, compensating for the inherent delays in the switch mode power supply converter control loop and output current sensing. This allows the system to proactively respond to voltage changes rather than reactively responding after delays occur.
2Use of energy by moving object
If feedback delay compensation is implemented to reduce control delays, then power efficiency is improved, but system complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the switching thresholds of the power supply converter based on the derivative of the VRAMP signal. Instead of changing the physical structure or adding complex control logic, the system adjusts the voltage threshold parameters dynamically. The feedback delay compensation circuit computes d(VRAMP)/dt and uses this to shift the switching thresholds, thereby compensating for delays through parameter adjustment rather than structural complexity.
3Use of energy by moving object
If switch mode power supply converter is used instead of parallel amplifier circuit, then power efficiency is improved, but voltage regulation accuracy is reduced
Solution Approach 1:
The patent applies feedback by implementing a feedback delay compensation circuit that continuously monitors the VRAMP signal and its derivative. The circuit uses d(VRAMP)/dt as feedback information to adjust the switching thresholds of the power supply converter, compensating for the inherent inaccuracies of switch mode conversion. This feedback mechanism allows the system to maintain voltage regulation accuracy comparable to parallel amplifier circuits while retaining the power efficiency benefits of switch mode operation.
Data Source
AI summary
A switch mode power supply converter and a feedback delay compensation circuit are disclosed. The switch mode power supply converter has a switching voltage output and provides a switching voltage at the switching voltage output, such that a target voltage for a power amplifier supply voltage at a power amplifier supply output is based on the switching voltage. Further, the switching voltage is based on an early indication of a change of the target voltage. The feedback delay compensation circuit provides the early indication of the change of the target voltage.