Element Mounting Substrate with Extended Transmission Line for Wideband Noise Filtering
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Solution Overview
Problem
Existing element mounting substrates face challenges in achieving high attenuation characteristics over a wide band due to the proximity of inductors, which reduces the effectiveness of noise filtering in electronic devices, especially when dealing with wide frequency bands or closely spaced noise frequencies.
Innovation Solution
The substrate design includes a transmission line connecting impedance elements in series, where the line length is longer than the shortest distance between them, allowing for high attenuation characteristics across a wide band by utilizing the characteristic impedance of the transmission line, thereby adjusting the anti-resonant frequency and enhancing noise filtering capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If inductors are arranged close to each other to reduce substrate size, then substrate area is reduced, but attenuation characteristics are lowered
Solution Approach 1:
A transmission line is introduced as an intermediary element between the first and second inductors. This transmission line has a specific characteristic impedance that forms a filter circuit with the inductors, enabling high attenuation characteristics even when the inductors are positioned close together. The transmission line mediates the interaction between the inductors to achieve both compact size and effective noise filtering.
2Area of stationary object
If transmission lines are connected at shortest distance between inductors, then substrate area is reduced, but attenuation characteristics are lowered
Solution Approach 1:
The transmission line serves as a mediator that transforms the simple shortest-distance connection into a functional filter circuit. By designing the transmission line with appropriate characteristic impedance and length, it creates antiresonance conditions that provide high attenuation, thereby resolving the contradiction between compact layout and filtering performance.
Solution Approach 2:
The characteristic impedance and length of the transmission line are carefully controlled as key parameters. By adjusting these parameters, the filter circuit achieves high attenuation characteristics at specific frequency bands while maintaining a compact substrate layout. The parameter optimization allows the system to achieve both small size and effective noise filtering.
3Adaptability or versatility
If multiple filter circuits are used for different frequency bands, then noise filtering in multiple bands is achieved, but device complexity increases
Solution Approach 1:
The filter circuit using the transmission line and inductors provides multi-functional noise filtering capability. By adjusting the characteristic impedance and length of the transmission line, the same basic circuit structure can target different frequency bands (such as 800 MHz and 1.5 GHz bands), eliminating the need for separate dedicated filter circuits for each band and reducing overall device complexity.
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 enables high attenuation characteristics in a wide band, effectively counteracting noise across multiple frequency bands, including those previously difficult to manage, such as the 800 MHz and 1.5 GHz bands, while allowing for miniaturization of the substrate without compromising performance.
Implementation Method 1
a line length between the first end and the second end in the transmission line is longer than a shortest distance between the first end and the second end... it is possible for a filter unit composed of the first impedance element, the transmission line, and the second impedance element to obtain high attenuation characteristics in a wide band by using the characteristic impedance of the transmission line
Implementation Method 2
antiresonance between the filter circuits prevents attenuation in frequency bands other than the frequency band of the external noise
Implementation Method 3
the usable frequency band is matched with a self-resonant frequency of a filter circuit including an impedance element such as an inductor, and a specific frequency band is set to high impedance
Data Source
AI summary
An element mounting substrate includes a substrate, a first impedance element and a second impedance element on a main surface of the substrate and each having an electrode, and a transmission line on the substrate and having a first end connected to the electrode of the first impedance element and a second end connected to the electrode of the second impedance element. The first impedance element and the second impedance element are electrically connected in series via the transmission line on the substrate, and a line length between the first end and the second end in the transmission line is longer than a shortest distance between the first end and the second end.