Doherty Amplifier Input Phase Networks for Wideband Efficiency
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Solution Overview
Problem
Current Doherty amplifiers experience efficiency degradation when amplifying wideband modulated RF signals, such as 5G New Radio signals, due to limitations in maintaining high efficiency across a wide frequency band.
Innovation Solution
Incorporating phase lead and phase lag components between the RF input and either the main or auxiliary amplifiers, along with a quarter wave component, to provide specific phase shifts that ensure maximum output power remains within ±0.5 dB of a target power across a frequency band defined by 3GPP or FCC standards, thereby enhancing the amplification efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional Doherty amplifier structure is used, then high efficiency at maximum output power is achieved, but efficiency degrades when amplifying wideband modulated RF signals
Solution Approach 1:
The patent introduces dynamic phase adjustment mechanisms (phase lead and phase lag components) that adapt the phase relationships between main and auxiliary amplifiers across different frequencies. This dynamic adaptation allows the amplifier to maintain optimal performance across wide frequency bands while preserving high efficiency, directly resolving the contradiction between efficiency and frequency adaptability.
Solution Approach 2:
The patent modifies key operational parameters including phase shifts (+(1-α)β and -αβ), amplitude relationships, and impedance transformations across the frequency band. By carefully controlling these parameter changes, the amplifier maintains constructive interference and high efficiency over wide bandwidths, solving the contradiction between narrowband efficiency and wideband adaptability.
2Adaptability or versatility
If phase lead and phase lag components are added to achieve target phase shift over wide frequency band, then operating bandwidth and efficiency are improved, but device complexity increases
Solution Approach 1:
The patent divides the phase adjustment function into separate, modular components: phase lead components connected to the main amplifier path and phase lag components connected to the auxiliary amplifier path. This segmentation allows independent optimization of each component and simplifies the overall design while achieving wideband performance, resolving the contradiction between complexity and adaptability.
Solution Approach 2:
The patent introduces intermediate phase adjustment networks (LC circuits, transmission lines) that mediate between the input signal and the main/auxiliary amplifiers. These intermediary components provide the necessary phase shifts without requiring direct modification of the amplifier cores, thereby achieving wideband coverage with minimal increase in overall system complexity.
Data Source
AI summary
This disclosure relates generally to Doherty amplifiers. In one embodiment, a Doherty amplifier includes an RF input of the Doherty amplifier for receiving a radio frequency (RF) signal, a main amplifier coupled to the RF input, and an auxiliary amplifier coupled to the RF input. A phase lag component connected between the RF input and one of either the main amplifier or the auxiliary amplifier and a phase lead component connected between the RF input and another one of either the main amplifier or the auxiliary amplifier. In some embodiments, the phase lead and phase lag components ensure that the split signals output from the main and auxiliary amplifier are recombined in phase throughout a frequency band.