Coaxial Load Pull Tuner Horizontal Probe Attenuator
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Solution Overview
Problem
Existing RF load and source pull testing methods for medium and high-power RF transistors and amplifiers require precise vertical axis mechanisms for slide screw impedance tuners, which are complex, prone to electrical sparking, and demand high precision, while also facing challenges with achieving a wideband 50Ω neutral state and controlling spurious oscillations.
Innovation Solution
A load pull tuner system using a horizontally-only high-speed tuning probe with an in-series adjustable attenuator and a vertically-only RF energy-absorbing device, eliminating the need for a vertical axis mechanism and allowing for wideband 50Ω neutral state creation, while reducing spurious reflections and oscillations through adjustable attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a vertical axis mechanism is used for slide screw impedance tuners, then tuning precision is improved, but device complexity increases and reliability decreases due to electrical sparking risks
Solution Approach 1:
The patent inverts the conventional vertical axis tuning mechanism by implementing a horizontal tuning probe movement instead. The tuning probe moves horizontally along the coaxial transmission line rather than vertically, eliminating the need for complex vertical axis mechanisms while maintaining tuning precision through the horizontal positioning system.
Solution Approach 2:
The patent extracts and eliminates the vertical axis mechanism entirely from the tuner design. By removing this complex component, the system reduces device complexity and associated reliability issues while achieving the same tuning function through horizontal probe movement controlled by a simplified positioning system.
2Measurement precision
If a vertical axis mechanism is used for slide screw impedance tuners, then tuning precision is improved, but reliability worsens due to electrical sparking
Solution Approach 1:
The patent inverts the conventional vertical axis tuning mechanism by implementing a horizontal tuning probe movement instead. The tuning probe moves horizontally along the coaxial transmission line rather than vertically, eliminating the need for complex vertical axis mechanisms while maintaining tuning precision through the horizontal positioning system.
3Adaptability or versatility
If conventional slide screw tuners are used, then impedance tuning capability is achieved, but spurious oscillations increase due to residual reflections
Solution Approach 1:
The patent introduces an intermediary component - an adjustable attenuator - positioned between the signal source and the tuning probe. This attenuator mediates the signal path by reducing the amplitude of residual reflections from the tuner, thereby suppressing spurious oscillations while preserving the impedance tuning capability of the horizontal probe system.
Solution Approach 2:
The patent converts the harmful residual reflections that cause spurious oscillations into a controllable parameter by using the adjustable attenuator. The attenuator transforms the harmful high-level reflections into manageable signal levels, turning a potential reliability issue into a controlled design parameter that can be optimized for different operating conditions.
4Adaptability or versatility
If conventional tuners are used, then impedance matching is achieved, but wideband 50Ω neutral state creation is difficult
Solution Approach 1:
The patent implements a universal tuning system where the horizontal probe movement mechanism can achieve multiple functions: precise impedance tuning across different frequencies and the creation of a wideband 50Ω neutral state. The simplified horizontal positioning system provides multi-functional capability that replaces the need for complex vertical axis mechanisms while achieving superior broadband performance.
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 simplifies the tuner design, reduces tuning error sensitivity, and effectively mitigates spurious oscillations across a large frequency bandwidth, enabling more stable and accurate impedance matching for potentially unstable RF components.
Implementation Method 1
the probe creates, at its own reference plane, a concentric reflection factor circle on the Smith chart
Implementation Method 2
an in series adjustable attenuator to mitigate the disadvantageous residual spurious reflection of the tuner
Data Source
AI summary
Coaxial load pull tuners use one horizontally-only moving metallic reflective probe inserted in the slabline at fixed penetration and an adjustable RF energy absorbing eccentrically into the slabline rotated disc. The tuner does not use high precision vertical axes. The remotely adjustable attenuator is inserted adjacent to the test port and mitigates spurious high reflection. Calibration procedures using de-embedding or adapter removal techniques allow high resolution full tuner characterization in a few minutes.