RF Power Amplifier Gain Feedback Without Output Isolators
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Solution Overview
Problem
RF power amplifiers in solid state cooking applications face challenges with impedance mismatches that can lead to permanent damage at high power levels, and existing solutions like isolators are costly and increase system footprint.
Innovation Solution
An RF power amplifier system with a control loop that adjusts output power based on the difference between actual and desired large signal gain, using an attenuator to mitigate damage by reducing power when mismatches occur, and employs a thermal unit to estimate dissipated power for accurate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the RF power amplifier operates at high output power, then productivity is improved, but the risk of permanent damage to components increases due to impedance mismatches
Solution Approach 1:
The patent implements a control loop that continuously monitors the large signal gain of the RF power amplifier and compares it with a desired gain value. When a mismatch is detected (actual gain deviates from desired gain), the system automatically adjusts the attenuator to reduce the input power level, preventing permanent damage to the RF power transistor while allowing high power operation under normal conditions
2Reliability
If an isolator is implemented at the output of the RF power transistor, then reliability is improved by dissipating reflected power, but device complexity and cost increase
Solution Approach 1:
Instead of using a passive isolator, the patent employs an active feedback control system that monitors the RF power amplifier's gain and dynamically adjusts the attenuator to prevent damage from reflected power. This approach eliminates the need for additional isolator components while maintaining protection functionality through intelligent power level control
Solution Approach 2:
The RF power amplifier system monitors its own performance parameters (large signal gain) and automatically adjusts its operating conditions through the control loop and attenuator, eliminating the need for external protective components like isolators. The system serves its own protection needs through self-monitoring and self-adjustment
3Reliability
If the RF power amplifier operates at strong back off to avoid damage, then reliability is improved, but power added efficiency deteriorates
Solution Approach 1:
The patent implements dynamic power level adjustment through a control loop that continuously adapts the attenuator setting based on real-time monitoring of large signal gain. The system operates at high power levels when conditions are favorable (maintaining high efficiency) and dynamically reduces power only when mismatches are detected, rather than operating continuously at reduced power levels
Data Source
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AI summary
The present invention relates to a radio-frequency (RF) power amplifier system for amplifying an RF signal. The present invention further relates to a telecommunications base station and a solid state cooking apparatus comprising such an RF power amplifier system and to a method for amplifying an RF signal. The invention proposes to regulate the power outputted by the power amplifier as a function of a comparison between the actual large signal gain and a desired large signal gain.