Filter With Planar Comb Electrodes For Stable Capacitance
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Solution Overview
Problem
Existing filters with resonators and dielectric sheets face variations in capacitance due to thickness changes, leading to inconsistent filter characteristics.
Innovation Solution
A filter design with resonators, via electrodes, and comb-shaped coupling capacitance electrodes formed in the same layer within a dielectric substrate, ensuring consistent electrostatic capacitance and positional alignment regardless of dielectric sheet thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling capacitance is formed using a coupling adjustment line between resonators, then resonator coupling is achieved, but capacitance varies when dielectric sheet thickness varies, leading to filter characteristic variation
Solution Approach 1:
The patent transitions from forming coupling capacitance in the thickness direction (between different dielectric sheets) to forming it in the planar direction (within the same dielectric sheet layer). The coupling capacitance electrodes are arranged adjacent to each other in the same layer, eliminating dependence on dielectric sheet thickness while maintaining effective capacitance for resonator coupling.
Solution Approach 2:
The patent uses comb-shaped electrode structures where multiple finger electrodes are formed in a planar arrangement. This copying of the electrode pattern within the same layer creates consistent capacitance values that are replicated across different resonator couplings, ensuring uniform filter characteristics regardless of dielectric thickness variations.
2Ease of operation
If resonators are coupled using capacitance formed across dielectric sheets, then resonator interaction is enabled, but positional misalignment occurs due to thickness variation
Solution Approach 1:
The patent relocates the coupling capacitance formation from the vertical dimension (across dielectric sheets) to the horizontal dimension (within the same layer). This planar arrangement of coupling capacitance electrodes eliminates the alignment problems caused by dielectric sheet thickness variations, as all electrodes are formed in the same manufacturing layer with precise positional control.
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 stabilizes filter characteristics by preventing variations in electrostatic capacitance and positional misalignment, maintaining performance across different thicknesses and frequencies.
Implementation Method 1
a first coupling capacitance electrode which is provided to a first resonator among the plurality of resonators and includes a first comb-shaped electrode including a plurality of first electrodes; and a second coupling capacitance electrode which is provided to a second resonator adjacent to the first resonator, includes a second comb-shaped electrode including a plurality of second electrodes
Data Source
AI summary
Provided is a filter capable of suppressing variation in characteristics. A filter has: a plurality of resonators each having a via electrode and a first strip line that is opposed to a first shielding conductor and connected to one end of the via electrode; a first coupling capacitive electrode that has a first comb-shaped electrode including a plurality of first electrodes and that is provided to the first resonator; and a second coupling capacitive electrode that is provided to the second resonator, that has a second comb-shaped electrode including a plurality of second electrodes, and that is formed on the same layer as that of the first coupling capacitive electrode, wherein the first and second electrodes are arranged so as to be adjacent to each other.