Transformer Outphasing Combiner for PA Isolation and Low Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional outphasing power combiners face inefficiencies due to power loss in dummy loads and interference between power amplifiers, leading to reduced linearity and spectral efficiency in RF transmitters.
Innovation Solution
An outphasing power combiner design that utilizes a transformer, load impedance, and ripple detector to match impedances and prevent power loss, allowing for isolating operation without dummy loads and minimizing amplifier interference, thereby enhancing power efficiency and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an isolating power combiner (Wilkinson combiner) is used, then power loss in dummy load occurs due to different phases of amplified constant-envelope signals, but if a non-isolating (low-loss) power combiner is used, then power amplifiers interfere with each other reducing linearity
Solution Approach 1:
The patent introduces a mediator circuit between the two power amplifiers that includes a first coupling circuit connected to the first power amplifier, a second coupling circuit connected to the second power amplifier, and a combining circuit that combines signals from both coupling circuits. This intermediary structure allows the power amplifiers to operate in isolation while combining their outputs, eliminating both the dummy load power loss and the amplifier interference problems
Solution Approach 2:
The patent segments the power combining function into separate coupling circuits for each power amplifier, with each coupling circuit handling one amplifier's output independently. The combining circuit then merges these segmented signals. This segmentation allows independent impedance matching and phase control for each amplifier path, resolving the contradiction between isolation and low loss
2Productivity
If variable-envelope signals are used for communication, then spectral efficiency is improved, but power efficiency deteriorates compared to constant-envelope signals
Solution Approach 1:
The patent segments the variable-envelope signal into two constant-envelope signals with different phases using the outphasing technique. Each constant-envelope signal is then amplified by a separate power amplifier operating in its efficient non-linear region. The segmented constant-envelope signals are subsequently combined to reconstruct the original variable-envelope signal, achieving both spectral efficiency and power efficiency
Solution Approach 2:
The patent changes the parameters of the signal by decomposing the variable-envelope signal into constant-envelope components with specific phase relationships. The power amplifiers operate with constant envelope parameters (amplitude), while the phase parameters are modulated to carry the information. This parameter transformation allows efficient amplification while maintaining spectral efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves higher power efficiency, longer battery life, smaller device sizes, and improved linearity, supporting higher data rates and spectral efficiency for advanced wireless communication standards like 5G and future generations.
Implementation Method 1
a first coupling circuit coupled to the first power amplifier, a second coupling circuit coupled to the second power amplifier, and a combining circuit coupled to the first and second coupling circuits
Implementation Method 2
The ripple detector is coupled to a terminal of the transformer. The ripple detector may be configured to detect voltage ripples at a terminal of the antenna
Data Source
AI summary
A circuit includes a transformer having a primary coil coupled to a first power amplifier (PA) and a second PA, and a secondary coil. The secondary coil supplies a current to an antenna based on a first direction of a first phase of a first amplified constant-envelope signal in the primary coil with respect to a second phase of a second amplified constant-envelope signal in the primary coil. The circuit further includes load impedance coupled between a median point of the primary coil and ground. The load impedance dissipates the current based on a second direction of the first phase of the first amplified constant-envelope signal in the primary coil with respect to the second phase of the second amplified constant-envelope signal in the primary coil, which results in improved power efficiency.