RF Power Amplifier Supply Circuit With Current-Sense Shutdown
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Solution Overview
Problem
Current methods for RF power amplifiers in mobile-phone terminals, which use current-limiting circuits to prevent battery drain during impedance mismatches, can lead to prolonged battery discharge and system failures when impedance mismatch conditions persist, potentially causing overheating and terminal breakdowns.
Innovation Solution
A power-supply circuit that includes a source-current-sensing circuit and a current-control unit to dynamically adjust the source current of the RF power amplifier, allowing for a shutdown mechanism when excessive current is detected, thereby reducing battery drain and preventing system failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current-limiting circuit is used to prevent battery drain during impedance mismatches, then battery protection is improved, but the system may still experience prolonged battery discharge and overheating when impedance mismatch conditions persist
Solution Approach 1:
The patent implements a feedback mechanism where the power supply voltage is monitored and adjusted based on the operating state of the RF power amplifier. The control circuit receives feedback signals indicating impedance mismatch conditions and dynamically adjusts the power supply voltage to prevent excessive current draw while maintaining normal operation during matched conditions.
Solution Approach 2:
The power supply circuit transitions from a static current-limiting approach to a dynamic voltage-adjustment system. The power supply voltage is continuously adjusted based on real-time monitoring of the RF amplifier's operating state, allowing the system to adapt to changing impedance conditions and prevent both battery drain and overheating.
2Use of energy by moving object
If the RF power amplifier operates in saturation to achieve good power efficiency, then energy efficiency is improved, but the system becomes more sensitive to impedance mismatch conditions
Solution Approach 1:
The control circuit performs preliminary detection of impedance mismatch conditions before they cause harmful effects. By monitoring the operating state of the RF power amplifier in advance, the system can preemptively adjust the power supply voltage to prevent excessive current draw and maintain stable operation even when operating in saturation for efficiency.
3Device complexity
If a simple current-limiting approach is used, then device complexity is reduced, but the system cannot prevent prolonged battery discharge during extended impedance mismatch conditions
Solution Approach 1:
The patent employs a feedback-based control system that monitors the RF power amplifier's operating state and adjusts the power supply voltage accordingly. This feedback mechanism enables the system to detect and respond to impedance mismatch conditions, preventing prolonged battery discharge while maintaining relatively simple circuit architecture.
Data Source
AI summary
The RF power amplifier apparatus has an RF power amplifier and a power-supply circuit. The power-supply circuit controls the level of a source voltage supplied to the RF power amplifier in response to the level of a power-control signal. A sensing resistance produces a sense signal Vsen corresponding to a source current with respect to a source voltage. The current-control unit controls the source current ILDO in response to the sense signal Vsen. When Vsen coincides with an allowable sense signal level Vsh corresponding to a source current allowable level ILDO(Max), the current-control unit controls the source current ILDO to a limit current smaller than the allowable level ILDO(Max). Preferably, the limit current is a shutdown current when a shutdown switch is in an OFF state. Thus, the draining of the battery of a mobile-phone terminal can be reduced even when an impedance mismatch condition lasts for a long time.