Compact MEMS Switched Capacitor for Microwave Filters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switched capacitor structures for microwave filters are bulky, result in significant microwave losses, and have limited lifetime due to the separate integration of capacitors and MEMS switches, leading to increased size and reduced longevity.
Innovation Solution
A compact switched capacitor structure where the capacitor is directly integrated into the MEMS switch, comprising a series MEMS switch with a metallic membrane and dielectric layer, allowing for adjustable capacitance and reduced bulk, and utilizing a suspended membrane or cantilever beam design to minimize losses and enhance longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate integrated capacitor and MEMS switch structure is used, then the switched capacitor can be implemented with good microwave performance, but the overall size increases and occupies more space in the integrated circuit
Solution Approach 1:
The patent merges the capacitor and MEMS switch into a single integrated structure where the capacitor is formed directly within the switch architecture. The first and second layers of metal form capacitor electrodes, with the dielectric layer between them, eliminating the need for separate capacitor and switch components and reducing overall device area.
2Reliability
If separate integrated capacitor and MEMS switch structures are used with connection lines, then the switched capacitor can be implemented, but microwave losses increase due to multiple interfaces
Solution Approach 1:
By integrating the capacitor directly into the MEMS switch structure, the patent eliminates multiple interfaces between separate components. The continuous metal layers and reduced number of connection points minimize reflection and insertion losses, improving overall microwave performance.
3Ease of manufacture
If a conventional MEMS switch structure is used, then the switch can be integrated, but the service life is limited due to the lifetime of the MEMS switch
Solution Approach 1:
The integrated structure allows the capacitor and MEMS switch to age together as a single unit, eliminating wear at connection interfaces between separate components. This unified architecture reduces stress concentration and potential failure points, extending overall device lifetime.
4Reliability
If separate integrated capacitor and MEMS switch structures are used, then the switched capacitor can be implemented, but the number of operating cycles is reduced
Solution Approach 1:
The monolithic integration of capacitor and switch reduces the mechanical travel distance and switching time by eliminating interface delays. The unified structure allows faster, more reliable switching operations that can withstand greater numbers of operating cycles without degradation.
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 integrated structure reduces overall size, minimizes microwave losses, and significantly increases the number of operating cycles, thereby extending the service life of the switched capacitor.
Implementation Method 1
the membrane in the low state establishing an ohmic contact between the parts of the second layer of metal located on either side and on the other side of the line break
Implementation Method 2
the capacitor to be switched being formed by the layer of dielectric material between the facing surfaces of the first layer of metal and of the second layer of metal
Implementation Method 3
a layer of dielectric material
Data Source
Figure 1~2b
Figure 3~4b
Figure 5~6
AI summary
The capacitor (400) has a series microelectromechanical system (MEMS) switch i.e. suspended membrane type series MEMS switch, provided with a metal layer (403), a dielectric layer (404) and an operable metallic membrane (411) attaining high and low states. Another metal layer (405) is formed on a part of a surface of the dielectric layer. The dielectric layer is formed between a contact surface of the former metal layer and the latter metal layer. The metallic membrane at low state is provided in direct contact with the latter metal layer. An independent claim is also included for a frequency tunable filter comprising oscillating circuits.