RF MEMS Switch Structure for Self-Actuation and Self-Biasing Control
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Solution Overview
Problem
RF switches, particularly capacitive shunt fixed-fixed beam type switches, experience self-actuation and self-biasing issues due to high-power RF signal transmission, leading to distortion and power limitations.
Innovation Solution
The RF MEMS switch incorporates a new structure with a substrate, first and second signal lines, a ground bridge, and capacitors to branch the RF signal, applying a symmetrical electric force to the signal line, thereby reducing or preventing shaking of the moving structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-power RF signal is transmitted through the switch-on state, then RF signal transmission capability is improved, but self-actuation and self-biasing occur causing signal distortion
Solution Approach 1:
The patent introduces asymmetry by adding a second signal line parallel to the first signal line, creating an unbalanced structure that deliberately generates a counteracting electromagnetic force to offset the self-actuation caused by high-power RF signals, thereby maintaining signal integrity while enabling high-power transmission
2Reliability
If membrane electrode contacts signal line to shunt RF signal (switch-off state), then isolation characteristic is improved, but self-biasing phenomenon occurs due to RF power
Solution Approach 1:
The patent introduces a second signal line as an intermediary element that mediates the electromagnetic interaction between the membrane electrode and the first signal line, creating a balanced force field that prevents unwanted self-biasing while maintaining effective signal shunting when needed
3Reliability
If new structure with second signal line and capacitors is added, then self-actuation and self-biasing are reduced, but device complexity increases
Solution Approach 1:
The patent segments the signal transmission path by introducing a second signal line parallel to the first, and divides the capacitive coupling into two separate capacitors (first capacitor between first signal line and second signal line, second capacitor between second signal line and ground), making the complex electromagnetic balancing mechanism more manageable and manufacturable
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
This configuration effectively reduces self-actuation and self-biasing, enhancing the power handling capability of the RF switch and maintaining signal integrity.
Implementation Method 1
a first capacitor formed between the first point of the first signal line and one end of the second signal line; and a second capacitor formed between the second point of the first signal line and the other end of the second signal line
Implementation Method 2
a ground bridge disposed to be at least partially movable in a space between the first signal line and the second signal line disposed on the substrate and connected to a ground
Data Source
AI summary
A switch in an electronic device includes a substrate, a first signal line, a second signal line, and a ground bridge. The first signal line is on the substrate and extends in a first direction. The second signal line is on the substrate and is spaced apart from the first signal line in a first direction parallel with the first signal line to branch the wireless communication signal at a first point and a second point of the first signal line. The ground bridge is at least partially movable in a space between the first signal line and the second signal line. A first capacitor is between a first point of the first signal line and one end of the second signal line, and a second capacitor is between a second point of the first signal line and the other end of the second signal line.