Switched RF Power Amplifier for High-PAPR Efficiency
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Solution Overview
Problem
Radio frequency power amplifiers face efficiency degradation due to high peak-to-average power ratio (PAPR) in signals, leading to low average efficiency as they operate below peak output power to avoid saturation, necessitating an improvement in amplification efficiency for systems with high PAPR.
Innovation Solution
A dual-switching power amplifier system comprising two or more class E power amplifiers with different maximum output powers, where control circuitry selectively activates and deactivates the amplifiers via bias voltages applied to their gates, allowing for efficient amplification and combining their outputs without additional combining circuitry, thereby improving linearity and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single power amplifier operates below peak output power to avoid saturation, then linearity is improved, but efficiency deteriorates
Solution Approach 1:
The system divides the amplification task into multiple segments by using multiple power amplifiers with different maximum output powers. Each amplifier handles a specific power range, with the lowest-power amplifier operating at its peak for maximum efficiency while maintaining required linearity. This segmentation resolves the contradiction by allowing each amplifier to operate in its optimal efficiency region rather than forcing a single amplifier to operate below peak power.
Solution Approach 2:
The control circuitry dynamically switches between different amplifiers based on the instantaneous signal power level. When signal power is low, the lowest-power amplifier is activated; when signal power increases, other amplifiers are activated or deactivated. This dynamic switching ensures that the active amplifier always operates near its peak output power for maximum efficiency while still handling the full dynamic range of input signals with appropriate linearity.
2Loss of energy
If multiple power amplifiers with different maximum output powers are used, then efficiency across wider power range is improved, but device complexity increases
Solution Approach 1:
The outputs of multiple power amplifiers are merged together at a common output node without requiring additional combining circuitry. The amplifiers share common components including input signal distribution, output combining, and control circuitry. This merging approach achieves the efficiency benefits of multiple amplifiers operating at peak power while minimizing the increase in system complexity through component sharing and direct output combination.
3Loss of energy
If power amplifiers are operated at peak output power, then efficiency is improved, but the ability to accommodate large signal peaks deteriorates
Solution Approach 1:
The system segments the signal amplification task across multiple amplifiers with different power capabilities. The lowest-power amplifier handles average signal levels at peak efficiency, while higher-power amplifiers are activated when large signal peaks occur. This segmentation allows the system to maintain high efficiency during normal operation while still accommodating large signal peaks without clipping or distortion.
Solution Approach 2:
The control circuitry dynamically adjusts which amplifiers are active based on the instantaneous signal power level. When large signal peaks are detected, the control circuitry activates appropriate higher-power amplifiers to handle the peak while keeping lower-power amplifiers inactive or deactivated. This dynamic adaptation maintains high efficiency during average operation while providing the necessary headroom for large signal peaks.
Data Source
AI summary
An amplifier for amplifying radio frequency signals comprising: a signal splitter configured to split an input radio frequency signal into two or more signals; and two or more switching power amplifiers. Each of the switching power amplifiers is configured to amplify a respective signal of the two or more signals using an active device and output a respective amplified signal at a respective output terminal of the switching power amplifier when the switching power amplifier is activated. Each of the two or more switching power amplifiers has a different maximum output power. The amplifier further comprises: an output node connected to each of the output terminals of the switching power amplifiers to combine the amplified signals and output a combined amplified signal; and control circuitry configured to issue control signal to control bias voltages provided to a gate of each of the active devices of the switching power amplifier to selectively activate and deactivate the active devices.