Variable Capacitor With Movable Electrode For RF Stability
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Solution Overview
Problem
Existing variable capacitors in RF blocks face challenges in achieving a variable capacitance value that can range infinitely, as they are limited by the size of the electrode overlap area and are prone to changes under high RF power applications.
Innovation Solution
A variable capacitor design featuring a movable first electrode with an insulating film and a fixed second electrode, where the driving force can be electrostatic, piezoelectric, heat, or magnetic, allowing for 2-axial movement to vary the overlap area and thus the capacitance value, with the electrodes closely adhering to maintain stability under RF power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the electrode overlap area is increased to achieve higher capacitance values, then the capacitance range is improved, but the device size and complexity increase
Solution Approach 1:
The patent employs a movable electrode that can dynamically adjust its position relative to the fixed electrode, enabling continuous variation of the overlap area. This dynamic configuration allows the capacitance to be tuned across a wide range without requiring multiple fixed electrode structures, thereby achieving high adaptability while maintaining device simplicity.
Solution Approach 2:
The invention introduces a spatial dimension by moving the electrode in two axes (X and Y directions) rather than relying solely on increasing the overlap area in a single plane. This dimensional approach enables infinite capacitance variation within a compact footprint, resolving the contradiction between capacitance range and device size/complexity.
2Power
If high RF power is applied to achieve higher power handling capability, then the power transmission is improved, but electrostatic attraction causes capacitance value instability
Solution Approach 1:
The patent introduces an insulating film as an intermediary layer between the movable electrode and the fixed electrode. This intermediate layer prevents direct electrostatic attraction between the electrodes when high RF power is applied, thereby maintaining capacitance value stability while allowing high power handling capability.
3Area of stationary object
If the electrode overlap area is reduced to decrease device size, then the device compactness is improved, but the capacitance adjustment range is limited
Solution Approach 1:
By implementing a movable electrode that can dynamically adjust its position, the patent enables a compact device design to achieve a large capacitance tuning range. The dynamic reconfiguration of the electrode overlap area allows the device to provide variable capacitance values without requiring a large physical footprint.
Solution Approach 2:
The invention utilizes two-axis movement of the electrode to exploit additional spatial dimensions for capacitance adjustment. This approach enables the device to achieve infinite capacitance variation within a minimal footprint by changing the overlap area through positional adjustments rather than increasing the overall device area.
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 design enables a stable capacitance value that does not change under high RF power and allows for an infinite variable range by determining the capacitance based on the overlap area, enhancing the tuning capabilities of RF devices.
Implementation Method 1
a first electrode is fixed closely attaching to a second electrode formed with an insulating film, a set capacitance value is not subject to change at all when a high RF power between a first electrode and a second electrode is applied, which occurring an electrostatic attraction
Implementation Method 2
a driving force moving the first electrode or the second electrode is one of electrostatic force, piezoelectric force, heat driving force and magnetic force
Implementation Method 3
a driving force moving the first electrode or the second electrode is one of electrostatic force, piezoelectric force, heat driving force and magnetic force
Implementation Method 4
a driving force moving the first electrode or the second electrode is one of electrostatic force, piezoelectric force, heat driving force and magnetic force
Implementation Method 5
according to a size of an area overlapped with the first electrode and the second electrode, a capacitance value varies
Data Source
Figure 1~(2b)
Figure 3~(3d)
Figure 4~(4b)
AI summary
Disclosed herein is a variable capacitor and its driving method, the variable capacitor including, a movable first electrode; and a second electrode formed with an insulating film, fixed in place, and its insulating film contacting the first electrode that is moved.