Envelope-Controlled Load Modulation for Wide-Range RF Power Amplifiers
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Solution Overview
Problem
Existing RF power amplifiers in mobile devices face challenges in achieving high efficiency over a wide dynamic range, particularly in 5G communication systems with high peak-to-average power ratio (PAPR) waveforms.
Innovation Solution
The implementation of a load modulated power amplifier system, which includes a power amplifier and a controllable load impedance. The controllable load impedance is modulated by an envelope signal that changes in relation to the envelope of the RF signal, allowing for efficient impedance control and high efficiency amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional power amplifiers are used in mobile devices, then they can amplify RF signals, but they cannot achieve high efficiency over a wide dynamic range
Solution Approach 1:
The patent applies dynamics by making the load impedance adjustable and variable rather than fixed. The load impedance network includes switches that can dynamically reconfigure the impedance values based on the operating conditions, allowing the power amplifier to maintain high efficiency across a wide dynamic range by adapting to different signal power levels
Solution Approach 2:
The patent changes the impedance parameters of the load network to optimize power amplifier efficiency. By varying the load impedance values according to the signal envelope, the system achieves high power added efficiency across different operating points and dynamic conditions
2Loss of energy
If envelope tracking amplifiers are used to achieve high efficiency, then power added efficiency improves, but device complexity increases
Solution Approach 1:
The load impedance network serves multiple functions: it provides impedance transformation, enables dynamic load modulation, and offers reconfigurability for different operating modes. This multi-functional design achieves high efficiency without requiring separate envelope tracking circuits, reducing overall system complexity
Solution Approach 2:
The power amplifier system self-regulates its efficiency by using the load impedance network to automatically adapt to varying signal conditions. The system monitors its own operating state and adjusts the load impedance accordingly, eliminating the need for external envelope tracking control circuits
Data Source
AI summary
Apparatus and methods for load modulated power amplifiers are provided. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency signal at an input and provides an amplified radio frequency signal at an output, and a controllable load impedance coupled to the output of the power amplifier. The controllable load impedance receives an envelope signal that changes in relation to an envelope of the radio frequency signal, and the envelope signal is operable to control an impedance of the controllable load impedance to modulate a load at the output of the power amplifier.