RF Power Amplifier Supply Control Across Boost-Buck Modes
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Solution Overview
Problem
Switched-mode power supplies in RF power amplifiers for battery-powered wireless devices face inefficiencies at low transmission power levels due to cascaded Boost and Buck converters, which are exacerbated by declining battery voltages, and existing solutions like Buck-Boost converters struggle with frequency and group delay requirements in envelope elimination and restoration techniques.
Innovation Solution
A control method and apparatus that measure battery voltage and dynamically switch between Boost and Buck converters, bypassing the Boost converter when battery voltage exceeds the needed input, and controlling the Buck converter's operation based on power amplifier modes, frequency bands, and modulation methods to optimize supply voltage and switching frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a Boost-type switched-mode power supply is used to up-convert battery voltage to achieve high transmission power, then the needed output transmission power can be easily obtained, but the efficiency at small transmission power levels is poor
Solution Approach 1:
The patent implements dynamic switching between Boost and Buck converters based on real-time transmission power requirements. The system transitions from a static Boost converter configuration to a dynamic architecture that selects the appropriate converter type (Boost or Buck) according to the current power level, thereby optimizing efficiency across the entire power range from small to large transmission powers
Solution Approach 2:
The system changes the operating parameters of the power supply by switching between two different converter modes (Boost and Buck) based on transmission power levels. This parameter change allows the system to adapt its voltage conversion strategy dynamically, using Boost conversion when high power is needed and Buck conversion when low power is sufficient, thus resolving the efficiency problem at small transmission power levels
2Device complexity
If a Buck-Boost converter is used to automatically change mode to provide supply voltage for good efficiency at any transmission power level, then no cascading is needed, but distortion occurs in the critical output voltage range and frequency response is affected
Solution Approach 1:
The patent implements dynamic mode selection between separate Boost and Buck converters based on real-time power level requirements, replacing the static Buck-Boost converter architecture. This dynamic approach allows smooth transitions between converter types at optimized power thresholds, avoiding the distortion and frequency response issues that occur in the critical transition range of Buck-Boost converters while maintaining architectural simplicity
Data Source
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AI summary
Switched-mode power supplies (SMPSs) and their control methods for radio frequency (RF) power amplifiers in battery-powered wireless transmitter devices. According to embodiments of the invention, a Boost-type SMPS and a Buck-type SMPS in cascade connection are controlled so that high efficiency is maintained for various loads and transmission power levels. The Boost SMPS and the Buck SMPS can be controlled based on the mode of operation of the transmitter, such as the actual battery voltage, the needed output power, the selected frequency band, the selected RF power amplifier (PA), the selected modulation method of the transmission signal, and/or the selected PA voltage control method, such as the envelope elimination and restoration (EER) technique, the envelope tracking (ET) technique, or the power-level tracking (PT).