Band-Pass Filter Layout for Low-Side Attenuation and Reduced Coupling
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Solution Overview
Problem
Existing band-pass filters face challenges in achieving sufficient pass attenuation on the low-pass side of the passband due to unintended magnetic coupling between inductors in miniaturized designs.
Innovation Solution
The band-pass filter configuration includes a series of high-pass filters with distinct attenuation pole frequencies, where the second high-pass filter has a higher frequency attenuation pole than the first and third high-pass filters, and no low-pass filter is provided between the first and second high-pass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If miniaturization of band-pass filter is implemented using stacked dielectric and conductor layers, then the size and footprint are reduced, but unintended magnetic coupling occurs between inductors of high-pass and low-pass filters
Solution Approach 1:
The patent applies dimensionality change by making the magnetic flux directions of adjacent inductors orthogonal to each other. Specifically, the high-pass filter inductor has its magnetic flux direction substantially perpendicular to the magnetic flux direction of the low-pass filter inductor, achieved through different winding orientations in the stacked layer structure. This spatial arrangement in three dimensions prevents magnetic coupling while maintaining miniaturization.
2Reliability
If multiple high-pass filters are provided to increase pass attenuation on low-pass side, then pass attenuation is improved, but magnetic coupling between multiple inductors occurs
Solution Approach 1:
The patent extends the orthogonal arrangement principle to multiple high-pass filter inductors. Adjacent inductors in the series connection are arranged with substantially perpendicular magnetic flux directions, preventing magnetic coupling between them while maintaining the multiple high-pass filter configuration for enhanced pass attenuation.
Solution Approach 2:
The patent applies local quality by making each inductor's magnetic flux direction locally orthogonal to its neighbors. This localized differentiation in orientation (some inductors wound in one direction, others perpendicular) prevents magnetic coupling at each interface while allowing the overall system to achieve high pass attenuation through the series connection of multiple high-pass filters.
3Reliability
If the frequency of the attenuation pole formed by the second high-pass filter is set higher than that of the first and third high-pass filters, then pass attenuation on low-pass side is increased, but the circuit configuration becomes more complex
Solution Approach 1:
The patent applies parameter changes by strategically setting the attenuation pole frequency of the second high-pass filter higher than that of the first and third filters. This frequency parameter differentiation creates effective pass attenuation on the low-pass side. The specific frequency values are optimized to achieve the desired attenuation characteristics while managing the complexity of the circuit configuration.
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 increases pass attenuation on the low-pass side of the passband by minimizing magnetic coupling between the high-pass filters, thereby enhancing the filter's performance in miniaturized designs.
Implementation Method 1
Each of the high-pass filter and the low-pass filter includes an inductor
Implementation Method 2
miniaturization of the stack causes unintended magnetic coupling occurring between an inductor of the high-pass filter and an inductor of the low-pass filter
Data Source
AI summary
A band-pass filter includes a first port, a second port, first to third high-pass filters provided between the first port and the second port in this order from a first-port side in a circuit configuration, and a low-pass filter provided between the second high-pass filter and the third high-pass filter in the circuit configuration. Each of the first to third high-pass filters forms an attenuation pole on a low-pass side of the passband. A frequency of the attenuation pole formed by the second high-pass filter is higher than a frequency of the attenuation pole formed by each of the first and third high-pass filters.