Doherty Amplifier Input Power Steering for Low-Level Efficiency
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Solution Overview
Problem
Conventional Doherty power amplifiers experience reduced efficiency at lower output levels, particularly for complex modulation like OFDM, due to wastage of signal power when the auxiliary amplifier is not turned on, which limits the overall power efficiency of wireless devices.
Innovation Solution
An improved Doherty power amplifier design incorporates a hybrid plus coupler and phase shifter to dynamically control power distribution between the main and auxiliary amplifiers based on detected power levels, optimizing input power utilization and enhancing efficiency at low power levels by steering power to the main amplifier and away from the auxiliary amplifier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional Doherty power amplifier uses a power splitter to divide input power between main and auxiliary amplifiers, then high output power capability is achieved, but signal power is wasted when the auxiliary amplifier is not turned on, reducing efficiency at lower output levels
Solution Approach 1:
The patent implements dynamic power distribution control by detecting the input signal power level and adjusting the phase shifter accordingly. When signal power is below a threshold, the phase shifter redirects power away from the auxiliary amplifier; when signal power exceeds the threshold, normal Doherty operation resumes. This dynamic adaptation eliminates static power waste while maintaining high output capability.
Solution Approach 2:
The patent changes the phase parameter of the signal directed to the auxiliary amplifier based on detected power levels. By adjusting the phase shift amount dynamically, the system optimizes power distribution between amplifiers, directing power to the main amplifier when auxiliary should remain off, and enabling auxiliary participation when needed for high power operation.
2Loss of energy
If the auxiliary amplifier remains off at lower output levels to save power, then efficiency improves, but the signal power directed to it is wasted without proper redistribution
Solution Approach 1:
The patent introduces a phase shifter as an intermediary component between the power splitter and the auxiliary amplifier. This mediator dynamically adjusts the phase of the signal destined for the auxiliary amplifier based on detected power levels, effectively redirecting unused signal power to the main amplifier when the auxiliary should remain off, thereby preventing power waste while maintaining efficiency.
Solution Approach 2:
The patent implements a feedback mechanism where the detected power level from the input signal is used to control the phase shifter's operation. The detector monitors signal power and provides feedback that determines whether to redirect power away from the auxiliary amplifier, creating a closed-loop system that optimizes power distribution based on real-time conditions.
Data Source
AI summary
A novel Doherty amplifier with improved efficiency is disclosed. In an exemplary embodiment an apparatus includes a phase shifter configured to generate a phase shifted first millimeter (MM) wave signal based on a selected phase shift, and a hybrid plus coupler comprising output terminals and configured to adjust output power levels at the output terminals based on combinations of the phase shifted first MM wave signal and a second MM wave signal.