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 due to resistor dissipation and interference between power amplifiers, leading to reduced linearity and increased error vector magnitude (EVM) in RF signals.
Innovation Solution
A low-loss isolating outphasing power combiner is designed, which decomposes variable-amplitude RF signals into constant-amplitude signals, amplifies them using separate power amplifiers with minimized interference, and combines them using a power combiner with impedance matching and transformer configurations to minimize power dissipation and interference.
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 due to resistor dissipation, 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 isolating element (resistor or isolation network) as an intermediary component in the power combiner circuit. This intermediary absorbs the harmful interference between power amplifiers while allowing the useful power signals to pass through with minimal loss, thus resolving the contradiction between power loss and linearity maintenance
Solution Approach 2:
The patent optimizes the impedance values and configuration of the isolating elements to achieve a balance point where sufficient isolation is provided without excessive power dissipation. By carefully selecting and adjusting parameters such as resistor values, Q-factors, and impedance transformations, the system achieves both low power loss and maintained linearity
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 enhances power efficiency, reduces distortion, and maintains linearity, thereby improving the overall performance of RF transmitters by minimizing power loss and interference between power amplifiers.
Implementation Method 1
a power combiner with impedance matching and transformer configurations
Implementation Method 2
a certain amount of power may be lost in a resistor within the power combiner due to the different phases of the two outphasing constant-envelope signals
Data Source
AI summary
The 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.