Waveguide Load Pull Tuner With Horizontal Probe and Fast Calibration
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Solution Overview
Problem
Existing RF load and source pull testing systems for medium and high-power RF transistors face challenges with precision and safety due to the complex and cumbersome vertical axis mechanisms in slide screw tuners, which are prone to electrical sparking and require high accuracy, making them incompatible with on-wafer integration and lacking a generic wideband calibration method.
Innovation Solution
A load pull tuner system utilizing a horizontally moving tuning probe and a pre-inserted adjustable attenuator, combined with a fast de-embedding calibration method, simplifies the design by eliminating the need for vertical axes and enabling precise impedance synthesis across a wideband, allowing for efficient and safe high-power tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vertical axis mechanisms are used in slide screw tuners to achieve precise impedance control, then tuning precision is improved, but device complexity and risk of electrical sparking increase
Solution Approach 1:
The patent removes the complex vertical axis mechanism from the tuner design. Instead of using a slide screw with vertical movement, the invention employs a simplified horizontal probe movement system where the probe is moved along a linear path without requiring precision vertical positioning mechanisms, thereby eliminating the complexity and sparking risks associated with vertical axes.
Solution Approach 2:
The patent inverts the traditional slide screw approach by using a fixed probe position with a moving ground plane or reference structure instead of moving the probe vertically. This inversion allows achieving the same impedance tuning effect without the problematic vertical axis mechanism.
2Adaptability or versatility
If tuning probes are positioned very closely to the center conductor to achieve high reflection, then tuning range is improved, but risk of electrical sparking increases
Solution Approach 1:
The patent introduces an intermediary structure (such as a dielectric support or modified probe geometry) between the tuning probe and the center conductor, allowing the probe to achieve the necessary electrical coupling for high reflection without direct contact or extremely close positioning, thereby reducing sparking risk while maintaining tuning range.
3Measurement precision
If complex vertical axis arrangements are used to achieve precise probe movement, then positioning accuracy is improved, but device size and complexity increase
Solution Approach 1:
The patent replaces the complex mechanical vertical axis system with a simpler mechanical or even electrostatic positioning system. The probe positioning is achieved through a linear actuator or simple translation mechanism along a horizontal axis, eliminating the need for complex vertical gears, belts, or lead screws, thereby reducing device size and complexity while maintaining positioning accuracy.
4Manufacturing precision
If traditional slide screw tuners are used for impedance matching, then impedance control is achieved, but compatibility with on-wafer integration is reduced
Solution Approach 1:
The patent segments the tuner into modular components that can be integrated onto the wafer substrate. The tuning probe and supporting structures are designed as separate modules that can be mounted directly on the wafer, allowing impedance matching functionality to be incorporated into the on-wafer test setup, thereby improving compatibility with on-wafer integration while maintaining impedance control capability.
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 system achieves precise impedance control with reduced complexity and size, enabling faster calibration and operation, reducing the risk of electrical sparking and improving compatibility with on-wafer integration while providing a wideband neutral state.
Implementation Method 1
an adjustable attenuator, which includes an absorbing sliver 44, which can be inserted 46 into a slot 47 in the waveguide 45
Implementation Method 2
a reflective tuning probe 55, which is held by a vertical axis 58 and can be moved 59 towards and away from the test port 91 by a linear actuator 52
Data Source
AI summary
A simple low-profile waveguide load pull tuner uses a horizontally only moving reflective probe and an adjustable attenuator placed between the DUT and the tuning probe. Both controls are using stepper attenuators mounted on the waveguide. This simplifies the design and minimizes the cost of manufacturing. The tuner has wideband 50 Ohm tuning capability allowing minimum risk of transient spurious oscillations. A de-embedding adapter removal calibration method allows generating thousands of calibrated points in a small fraction of the time needed for calibration of the full permutations.