Outphasing Amplifier Coupling Layout for Low-Loss Reactance Tuning
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Solution Overview
Problem
Existing outphasing amplifiers suffer from increased loss and difficulty in finely adjusting reactance components due to direct coupling between transmission lines and coupling circuits, which affects isolation and frequency dependence of insertion loss.
Innovation Solution
The outphasing amplifier design includes separate coupling circuits for each transmission line, with stubs and coupling lines that add reactance components opposite to the transmission lines, allowing for reduced coupling and easier adjustment of reactance, thereby suppressing loss and frequency dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a stub is directly provided on the transmission line, then coupling is achieved, but loss increases and reactance adjustment becomes difficult
Solution Approach 1:
The coupling circuit is divided into separate components: a coupling line connected to the transmission line, and a stub connected to the coupling line. This segmentation allows independent adjustment of the stub's reactance without affecting the transmission line, making reactance adjustment easier while reducing signal loss.
Solution Approach 2:
A coupling line is introduced as an intermediary between the transmission line and the stub. This coupling line acts as a mediator that enables the stub to provide reactance adjustment without directly coupling to the transmission line, thereby reducing signal loss and improving adjustability.
2Reliability
If direct coupling is used between transmission line and coupling circuit, then coupling is achieved, but isolation deteriorates
Solution Approach 1:
The coupling circuit is segmented into a coupling line and a stub connected in series. This segmentation creates better isolation between the transmission line and the stub, as the coupling line acts as a buffer that reduces direct interaction, thereby improving signal isolation while maintaining functional simplicity.
3Loss of energy
If stub is directly connected to transmission line, then reactance is added, but frequency dependence of insertion loss increases
Solution Approach 1:
The coupling line serves as an intermediary that decouples the stub from the transmission line. This reduces the direct frequency-dependent interaction between the stub and transmission line, thereby reducing the frequency dependence of insertion loss while keeping the coupling structure relatively simple.
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
This design improves efficiency and reduces loss in the outphasing amplifier by minimizing signal leakage and enabling precise reactance adjustment, maintaining consistent insertion loss across frequencies.
Implementation Method 1
The first coupling circuit may add a reactance component opposite to a reactance component of the first transmission line alone in a band of the outphasing amplifier to the first transmission line
Implementation Method 2
The second coupling circuit may add a reactance component opposite to a reactance component of the second transmission line alone in the band to the second transmission line
Data Source
AI summary
An outphasing amplifier includes a first amplifier configured to amplify a first signal, a second amplifier configured to amplify a second signal of which a phase difference from the first signal changes, and a synthesizer that has a first transmission line through which a third signal output from the first amplifier passes, a second transmission line through which a fourth signal output from the second amplifier passes, a first coupling circuit that is separately provided from the first transmission line and is coupled to the first transmission line, a second coupling circuit that is separately provided from the second transmission line and coupled to the second transmission line, and a node that synthesizes the third signal having passed through the first transmission line and the fourth signal having passed through the second transmission line.