High-Frequency Measurement Line Structure for Mode Conversion Loss Reduction
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Solution Overview
Problem
High-frequency measurement accuracy is compromised due to mode conversion loss and impedance mismatch when using ground-signal-ground probes with grounded co-planar waveguide transmission lines, especially at higher frequencies, leading to excessive reflection and loss.
Innovation Solution
A high-frequency measurement line structure featuring a multi-layer circuit board with a transition section and high-frequency probe pads, including a slot in the second metal layer to facilitate mode conversion between the multi-conductor transmission line and the probe, optimizing the slot's width and shape to reduce radiation loss and signal coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If grounded co-planar waveguide transmission line is used with ground-signal-ground probe, then the structure is compatible with multi-layer board integration and substrate thickness requirements, but mode conversion loss and impedance mismatch occur leading to measurement inaccuracy
Solution Approach 1:
The patent introduces a transition section as an intermediary structure between the ground-signal-ground probe and the grounded co-planar waveguide transmission line. This transition section includes a signal line with specific impedance transformation and ground plane configurations that gradually convert the electromagnetic mode from the probe to the transmission line, reducing mode conversion loss and impedance mismatch while maintaining compatibility with multi-layer board integration.
Solution Approach 2:
The patent employs parameter changes in the transition section, including varying the signal line width, adjusting the ground plane dimensions, and modifying the impedance values along the transition path. These parameter transformations enable smooth impedance matching between the probe and transmission line, reducing reflections and improving measurement accuracy while adapting to multi-layer board constraints.
2Device complexity
If ground-signal-ground probe is used to probe grounded co-planar waveguide, then the probe structure is simple and commonly available, but excessive reflection and loss occur at high frequencies reducing measurement accuracy
Solution Approach 1:
The transition section serves as an intermediary that bridges the simple ground-signal-ground probe and the grounded co-planar waveguide. It includes impedance transformation structures and ground plane designs that reduce signal reflection and energy loss at high frequencies, allowing the use of simple probes without sacrificing measurement quality.
Solution Approach 2:
The patent addresses high-frequency performance by introducing dimensional changes in the transition section, such as varying the thickness of dielectric layers, adjusting the height of signal lines, and modifying the three-dimensional arrangement of ground planes. These dimensional adjustments reduce parasitic effects and improve high-frequency signal integrity while maintaining probe simplicity.
Data Source
AI summary
A high-frequency measurement line structure includes a circuit board structure and a multi-conductor transmission line section, a high-frequency measurement probe pad section and a transition section which are formed by the circuit board structure, wherein the transition section is arranged between the multi-conductor transmission line section and the high-frequency measurement probe pad section to be connected to the multi-conductor transmission line section and the high-frequency measurement probe pad section. The high-frequency measurement probe pad section includes a group of high-frequency measurement probe pads arranged on a first metal layer of the circuit board structure to touch a high-frequency probe to transmit a high-frequency signal. A second metal layer of the circuit board structure defines a slot arranged in accordance with the high-frequency measurement probe pad section and the transition section to help a mode conversion between the high-frequency probe and the multi-conductor transmission line section.