Slow-Wave Microstrip Line With Alternating Width And Thickness
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Solution Overview
Problem
Current microstrip line structures in integrated circuits are limited in reducing the size and cost of passive components, particularly in microwave and millimeter-wave integrated circuits, due to high losses and inefficient use of board area, necessitating the development of advanced interconnects that promote slow-wave propagation.
Innovation Solution
The implementation of a slow-wave microstrip line structure with a signal layer having alternating wide and narrow portions of different thicknesses and heights, allowing for adjustable capacitance and inductance tuning by varying the thickness and spacing of these portions, and the incorporation of a cross-under metal layer to enhance capacitance, enabling compact and efficient design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional microstrip line structures are used, then the design and manufacturing are simple, but the passive components occupy large board area and have high losses
Solution Approach 1:
The signal layer is segmented into alternating wide and narrow portions along its length, creating a non-uniform microstrip line structure. This segmentation allows different sections to contribute differently to the overall electrical characteristics, enabling slow-wave propagation while maintaining manufacturability through standard fabrication processes.
Solution Approach 2:
Different portions of the signal layer are given different local qualities through varying width and thickness. The wide portions provide higher capacitance while the narrow portions provide higher inductance, creating a distributed structure that achieves slow-wave effects without requiring complex external components.
2Area of stationary object
If discrete passive components are used, then the circuit functionality is achieved, but 80% of the transceiver board area is occupied
Solution Approach 1:
The microstrip line structure merges multiple functions into a single interconnect element. It simultaneously serves as a transmission line, a delay line, and a frequency-selective structure, eliminating the need for separate discrete passive components and significantly reducing board area while increasing integration density.
Solution Approach 2:
The non-uniform microstrip line structure provides multi-functionality by achieving slow-wave propagation, impedance transformation, and frequency selection all within the same interconnect structure, making it a universal solution for various RF circuit requirements.
3Area of stationary object
If on-chip passive components are integrated, then the space is reduced, but high losses occur in transmission lines and antennas
Solution Approach 1:
The microstrip line structure introduces dynamic electrical characteristics through its non-uniform geometry. The alternating wide and narrow portions create varying capacitance and inductance values along the line, enabling slow-wave propagation that reduces the electrical length and consequently reduces transmission losses without increasing physical chip area.
4Length of moving object
If slow-wave propagation is achieved through conventional structures, then the component size is reduced, but the characteristic impedance control is limited
Solution Approach 1:
The structure enables independent control of multiple parameters including width, thickness, and spacing of the signal layer portions. By varying these geometric parameters, the characteristic impedance and slow-wave factor can be independently tuned to achieve optimal performance for different frequency ranges and circuit requirements.
Data Source
AI summary
On-chip high performance slow-wave microstrip line structures, methods of manufacture and design structures for integrated circuits are provided herein. The structure includes at least one ground and a signal layer provided in a different plane than the at least one ground. The signal layer has at least one alternating wide portion and narrow portion with an alternating thickness such that a height of the wide portion is different than a height of the narrow portion with respect to the at least one ground.