Pseudo-Envelope Follower RF Supply With Ripple Current Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power management systems for mobile devices, particularly those using linear RF power amplifiers, face inefficiencies that limit battery life due to high power consumption, necessitating improved power management techniques to enhance power efficiency.
Innovation Solution
A pseudo-envelope follower power management system is introduced, comprising a parallel amplifier and a switch mode power supply converter that generate a power supply voltage for a linear RF power amplifier, with an open loop high frequency compensation assist circuit to cancel out high frequency ripple currents, thereby optimizing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear RF power amplifier is used in mobile devices, then good linearity and signal quality are achieved, but power consumption increases significantly
Solution Approach 1:
The power management system is divided into multiple functional blocks: a parallel amplifier for high-frequency ripple compensation, a switch-mode power supply converter for efficient power conversion, and a control circuit for regulating the power amplifier supply voltage. This segmentation allows each block to optimize for its specific function, achieving both signal quality and power efficiency.
Solution Approach 2:
The system dynamically adjusts the supply voltage to the linear RF power amplifier based on the instantaneous signal envelope. The parallel amplifier and switch-mode converter work together to provide real-time voltage modulation, enabling the amplifier to operate efficiently across varying signal conditions while maintaining signal integrity.
2Device complexity
If conventional power management systems are used, then simplicity is maintained, but power efficiency remains limited
Solution Approach 1:
The patent combines a parallel amplifier with a switch-mode power supply converter in a unified power management system. The parallel amplifier is connected in parallel with the main power supply path, allowing it to inject compensating ripple currents directly at the power amplifier supply node. This merging of functions achieves superior power efficiency without requiring complete system redesign.
Solution Approach 2:
The parallel amplifier acts as an intermediary component between the switch-mode power supply converter and the linear RF power amplifier. It processes the high-frequency ripple currents from the converter and delivers a compensated supply voltage to the RF amplifier, mediating the interaction between these two components to achieve both efficiency and simplicity.
3Power
If high frequency ripple currents are present in the power supply, then switch mode power supply operation is maintained, but signal quality deteriorates
Solution Approach 1:
The patent converts the harmful high-frequency ripple currents generated by the switch-mode power supply into a beneficial effect. The parallel amplifier detects these ripple currents and generates compensating currents that are injected back into the power supply path. This process transforms the harmful ripples into a mechanism for active ripple cancellation, improving signal quality while maintaining the efficiency benefits of switch-mode operation.
Solution Approach 2:
The system employs feedback mechanisms where the parallel amplifier continuously monitors the supply voltage and ripple currents from the switch-mode converter. Based on this feedback, the parallel amplifier adjusts its output to cancel the harmful ripples, creating a closed-loop control system that maintains signal quality despite the inherent ripple generation of switch-mode operation.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Embodiments disclosed in the detailed description relate to a pseudo-envelope follower power management system including a parallel amplifier and a switch mode power supply converter cooperatively coupled to generate a power supply voltage at a power supply output coupled to a linear RF power amplifier. The parallel amplifier output is in communication with the power amplifier supply output. The parallel amplifier governs operation of the switch mode power supply converter and regulates the power amplifier supply voltage base on a VRAMP signal. The parallel amplifier circuit includes an open loop high frequency compensation assist circuit that generates a high frequency ripple compensation current based on an estimate of the high frequency ripple currents contained in a ripple current of the power inductor. The high frequency ripple compensation current is injected into the parallel amplifier circuit output to cancel out high frequency ripple currents at the power amplifier supply output.