Meandered RF Termination Microstrip for High Power
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Solution Overview
Problem
Existing RF termination devices face challenges in achieving high frequency performance and power handling while maintaining a simple and cost-effective manufacturing process, particularly due to issues with parasitic capacitance and the complexity of stripline structures.
Innovation Solution
A lossy termination device is developed using standard thick film processes with a microstrip structure, featuring two meandered transmission lines with higher impedance and reduced length, allowing for efficient RF signal attenuation and reduced device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a thick film process deposits substantially rectangular resistive patches onto a dielectric layer to achieve high power handling, then power handling capability is improved, but parasitic capacitance increases which limits high frequency performance
Solution Approach 1:
The termination device is divided into multiple unit elements arranged in a grid pattern. Each unit element contains a resistive patch connected to ground through a via, with isolation trenches between them. This segmentation reduces the overall parasitic capacitance while maintaining power handling capability through the distributed structure.
Solution Approach 2:
The patent introduces isolation trenches filled with low dielectric constant material around each resistive patch and via structure. This creates locally optimized regions with reduced parasitic capacitance while maintaining the required power dissipation characteristics in the resistive patches themselves.
2Object-affected harmful factors
If additional tuning components (inductance) are employed to eliminate parasitic capacitance at resonant frequency, then high frequency performance is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the source of parasitic capacitance by introducing isolation trenches around resistive patches and vias. This removes the need for additional tuning components like inductors, achieving high frequency performance without increasing device complexity.
Solution Approach 2:
The patent converts the potentially harmful parasitic capacitance into a manageable parameter by using isolation trenches to control and reduce it to acceptable levels. This transforms the problem of parasitic capacitance from a harmful effect requiring complex compensation into a controlled design parameter.
3Object-affected harmful factors
If a lossy transmission line is used to achieve good high frequency response, then bandwidth is improved, but manufacturing complexity increases due to required multilayer stripline structure
Solution Approach 1:
The patent uses a simplified microstrip structure that copies the essential functionality of the lossy transmission line approach. Instead of implementing a complex multilayer stripline, the invention achieves similar high frequency performance using a single-layer microstrip with resistive patches and isolation trenches, greatly simplifying manufacturing.
4Power
If the size of the termination device is increased to improve power handling, then power handling capability is improved, but device size increases
Solution Approach 1:
The termination device is segmented into multiple unit elements that can be arranged in various configurations. This allows power handling capability to be scaled by adding more unit elements rather than increasing the size of individual elements, enabling modular scaling of power handling without proportional increases in overall device footprint.
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 provides improved high frequency performance and power handling capabilities while simplifying the manufacturing process and reducing the size and cost of the termination device, achieving a significant reduction in line length and linewidth, enabling implementation in a microstrip structure.
Implementation Method 1
The resistive patches are configured to convert the RF energy to thermal energy (i.e., I2R losses) so that the dielectric layer conducts the heat to the underlying heat sink
Implementation Method 2
the dielectric layer conducts the heat to the underlying heat sink
Data Source
AI summary
The present invention is directed to an RF termination device that includes a substrate having a first meandered transmission line disposed on a first surface thereof. The meandered first transmission line has a predetermined first transmission line length and a characteristic impedance substantially equal to twice the predetermined system impedance. One end of the first meandered transmission line is configured as an open circuit. A second meandered transmission line is disposed on the first major surface adjacent the first meandered transmission line. The meandered second transmission line has a predetermined second transmission line length and a characteristic impedance substantially equal to twice the predetermined system impedance. One end of the second meandered transmission line is coupled to the other end of the first transmission line and the other end is coupled to ground.