Transformer Outphasing Power Combiner for Low-Loss RF Isolation
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Solution Overview
Problem
Conventional outphasing power combiners in RF transmitters face issues of power loss and interference due to phase differences in constant-envelope signals, leading to inefficiencies and increased error vector magnitude (EVM) in wireless communication systems.
Innovation Solution
A low-loss isolating outphasing power combiner is designed, utilizing transformers and load impedances to match and combine amplified constant-envelope signals from separate power amplifiers, minimizing power dissipation and interference, and enhancing power efficiency by using differential or polarized antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an isolating power combiner (such as Wilkinson combiner) is used, then power loss occurs in the resistor due to phase differences, but if a non-isolating power combiner is used, then power amplifiers interfere with each other reducing linearity
Solution Approach 1:
The patent introduces an intermediary component (isolating element such as a resistor or isolation network) between the power amplifiers in the combiner circuit. This intermediary absorbs the harmful interference and phase differences between the constant-envelope signals, preventing direct interaction between amplifiers while minimizing power loss through proper impedance matching and placement.
2Use of energy by moving object
If power amplifiers operate with constant-envelope signals, then amplification efficiency improves, but phase differences cause power dissipation in the combiner
Solution Approach 1:
The patent converts the harmful phase differences between constant-envelope signals into a beneficial isolation mechanism. The isolating element uses the phase differences to create impedance mismatches that prevent interference between amplifiers, while the constant-envelope operation maintains high amplification efficiency. The energy that would otherwise be lost to interference is redirected through the isolating element in a controlled manner.
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 reduces power loss and interference, improving the linearity and efficiency of RF transmission by effectively combining amplified signals without significant power dissipation, thereby enhancing the overall performance of outphasing RF transmitters.
Implementation Method 1
utilizing transformers and load impedances to match and combine amplified constant-envelope signals
Implementation Method 2
utilizing transformers and load impedances to match and combine amplified constant-envelope signals from separate power amplifiers, minimizing power dissipation and interference
Data Source
AI summary
The power combiner circuit includes a transformer having a first primary coil coupled to a first power amplifier (PA), a second primary coil coupled to 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 first primary coil with respect to a second phase of a second amplified constant-envelope signal in the second primary coil. A first load impedance is associated with the first PA and a second load impedance is associated with the second PA. The first load impedance and the second load impedance receive currents from the first PA and second PA, respectively, based on a second direction of the first phase of the first amplified constant-envelope signal with respect to the second phase of the second amplified constant-envelope signal.