Millimeter-Wave Switching Device Via Hole Isolation
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Solution Overview
Problem
Conventional high-frequency switching devices in millimeter-wave communication systems face challenges in achieving high isolation with low insertion loss, particularly in small RF control circuits, due to parasitic components and increased chip size and manufacturing costs associated with multi-stage shunt structures.
Innovation Solution
A high-isolation switching device with a unit cell structure featuring symmetrically arranged ground via holes connected to input/output transmission lines, reducing the distance between via holes and transmission lines to enhance isolation without increasing insertion loss, thereby allowing for a smaller chip size and lower manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-stage shunt technique is used to ensure high isolation, then isolation is improved, but chip size increases due to additional components
Solution Approach 1:
The patent divides the shunt structure into multiple independent via holes (first, second, third, and fourth via holes) distributed at specific positions around the transmission line. Each via hole acts as an independent isolation element, collectively achieving high isolation without requiring a compact multi-stage configuration that would increase chip size.
Solution Approach 2:
The patent transitions from a planar multi-stage shunt configuration to a three-dimensional spatial arrangement of via holes at different heights and positions. The via holes are formed at first, second, third, and fourth positions with different depths, creating a vertical dimension for isolation that does not consume additional horizontal chip area.
2Reliability
If a multi-stage shunt technique is used to ensure high isolation, then isolation is improved, but manufacturing cost increases
Solution Approach 1:
The isolation function is segmented into multiple via holes that can be independently formed using standard semiconductor fabrication processes. Each via hole is a simple structural element that can be manufactured using conventional via formation techniques, avoiding the need for complex multi-stage assembly or specialized manufacturing processes.
Solution Approach 2:
The via holes are formed to extend through multiple layers of the semiconductor structure, with upper via holes formed through upper layers and lower via holes formed through lower layers. This self-organizing structure allows the isolation function to be achieved through the natural layering of the fabrication process, reducing manufacturing complexity and cost.
3Reliability
If transmission line and via holes are perpendicularly connected to minimize distance, then isolation is improved, but only 2 via holes can be disposed limiting isolation degree
Solution Approach 1:
The patent introduces a vertical dimension to the via hole configuration, with via holes formed at different depths (first and second via holes at first position, third and fourth via holes at second position). This vertical stacking allows more than two via holes to be disposed in a compact footprint, overcoming the limitation of planar arrangements while maintaining minimal distance from the transmission line.
Solution Approach 2:
The via hole structure is segmented into multiple groups at different positions (first position with first and second via holes, second position with third and fourth via holes). Each group serves as an independent isolation element, and the distributed arrangement around the transmission line maximizes the isolation effect without requiring complex interconnections between via holes.
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 achieves isolation of up to -29 dB in the millimeter-wave band without deteriorating on-state insertion loss, reducing chip size, and lowering manufacturing costs by eliminating the need for additional components like λ/4 transformers and multi-stage shunt structures.
Implementation Method 1
The shunt structure connects a ground via hole to a drain or source of a switching device, and adjusts the voltage of a gate, which is a control electrode, according to a millimeter-wave signal input to the source or drain electrode, thereby making an unwanted signal flow to ground and finally intercepting the flow to an output end.
Data Source
AI summary
Provided is a high-isolation switching device for a millimeter-wave band control circuit. By optimizing a cell structure to improve the isolation of an off-state without deteriorating the insertion loss of an on-state, it is possible to implement a high-isolation switching device useful in the design and manufacture of a millimeter-wave band control circuit such as a phase shifter or digital attenuator using switching characteristics. In addition, when a switch microwave monolithic integrated circuit (MMIC) is designed to use the switching device, it is not necessary to use a multi-stage shunt field effect transistor (FET) to improve isolation, nor to dispose an additional λ/4 transformer transmission line, inductor or capacitor near the switching device. Thus, chip size can be reduced, degree of integration can be enhanced, and manufacturing yield can be increased. Consequently, it is possible to reduce manufacturing cost.