Multilayer Bandpass Filter With Overlapping Inductor Loops
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Solution Overview
Problem
Existing multilayer bandpass filters face challenges in achieving a small-sized, low-loss design with steep attenuation at passband edges and low ripple in the passband, due to issues such as increased thickness, reduced Q values, and ripple in transfer characteristics.
Innovation Solution
A multilayer bandpass filter design featuring three or more LC parallel resonators with overlapping loop planes of inductor electrodes, coupled via loop electrodes, and a transverse electrode configuration to enhance coupling strength and reduce ripple, while maintaining low insertion loss and achieving desired inductance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the distance between LC parallel resonators is increased to reduce magnetic coupling and insertion loss, then the Q value improves, but the filter thickness increases
Solution Approach 1:
The patent transitions from planar coil patterns in separate layers to three-dimensional overlapping loop structures. The inductor electrodes are configured to overlap each other in the thickness direction, creating vertical magnetic coupling that achieves strong coupling without requiring large lateral distances, thus maintaining small filter thickness while reducing insertion loss.
Solution Approach 2:
Instead of using traditional lateral magnetic coupling between adjacent coils in the same or separate layers, the patent inverts the coupling approach by using vertical overlapping loops where the magnetic fields interact through the dielectric layer between overlapping electrodes, achieving coupling through a different spatial arrangement.
2Device complexity
If two-layer coil patterns are used to form LC resonators, then the resonator structure is established, but magnetic coupling becomes large and Q value decreases
Solution Approach 1:
The patent moves from two-dimensional planar coil patterns to three-dimensional overlapping loop structures. The inductor electrodes overlap vertically through dielectric layers, creating compact resonators with controlled magnetic coupling that maintain high Q values while establishing the necessary LC resonator structure.
3Volume of moving object
If LC resonators are disposed at different height levels to achieve small size, then the filter compactness improves, but the resonator-to-resonator distance for desired characteristics becomes difficult to control
Solution Approach 1:
The patent uses vertical overlapping of inductor electrodes through multiple dielectric layers to achieve compact three-dimensional arrangement. This overlapping configuration provides well-defined spacing controlled by the dielectric layer thicknesses, enabling precise control of resonator-to-resonator distance while maintaining small overall filter size.
Solution Approach 2:
The patent controls the magnetic coupling and resonator spacing by adjusting dielectric layer thicknesses and electrode overlap dimensions. By changing these geometric parameters, the resonator-to-resonator distance and coupling strength can be precisely controlled during manufacturing to achieve desired filter characteristics.
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 achieves a small-sized, low-loss bandpass filter with steep attenuation at passband edges and reduced ripple, utilizing overlapping inductor loops and a transverse electrode to optimize coupling and inductance, resulting in improved passband characteristics.
Implementation Method 1
a plurality of LC resonators are formed with a plurality of capacitances defined by a plurality of capacitor formation electrodes and inductances occurring on the plurality of capacitor formation electrodes, such that adjacent LC resonators are electromagnetically coupled with each other
Implementation Method 2
capacitances defined by a plurality of capacitor formation electrodes and inductances occurring on the plurality of capacitor formation electrodes
Data Source
AI summary
In a multilayer bandpass filter, capacitances are produced between a ground electrode provided in a ground electrode formation layer and capacitor electrodes provided in a capacitor electrode formation layer. A plurality of inductor electrodes are defined by via-electrodes and line electrodes such that loop planes of inductor electrodes at least partially overlap each other when seen in a direction in which the inductor electrodes are arranged. The direction of the loop of the inductor electrode of the LC parallel resonator located (at a first stage) at an input end is set to be opposite to the direction of the loop of the inductor electrodes of the LC parallel resonator (at a second stage) adjacent to the inductor electrode of the LC parallel resonator located at the input end. Similarly, the direction of the loop of the inductor electrode of the LC parallel resonator located (at a fifth stage) at an output end is set to be opposite to the direction of the loop of the inductor electrodes of the LC parallel resonator (at a fourth stage) adjacent to the inductor electrode of the LC parallel resonator located at the output end.