Shielded RF Filter Layout for Analog Signal Noise Rejection
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Solution Overview
Problem
The effectiveness of filtering in electronic devices for acquiring analog radiofrequency signals can be significantly reduced due to the placement of filtering units on the signal path, allowing external electromagnetic disturbances to degrade the performance of analog components.
Innovation Solution
The proposed solution involves placing a capacitive component of the filtering unit under the shielding and a filtering component in series on the signal path close to the shielding, which effectively filters electromagnetic disturbances and prevents noise from penetrating the analog subassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the filtering unit is placed on the signal path outside the shielding, then the filtering structure is simpler, but the filtering effectiveness decreases due to exposure to electromagnetic disturbances
Solution Approach 1:
The filtering unit is divided into two separate components: a first filtering component placed outside the shielding and a second filtering component placed inside the shielding. This segmentation allows each component to operate in its appropriate electromagnetic environment, with the first component handling initial filtering externally and the second component providing final filtering protection internally, thus resolving the contradiction between structural simplicity and filtering effectiveness.
Solution Approach 2:
The shielding acts as an intermediary element that physically separates the two filtering components. By placing the first filtering component outside and the second inside the shielding, the patent creates a staged filtering approach where the shielding itself serves as a protective mediator, preventing electromagnetic disturbances from directly affecting the sensitive second filtering component while allowing the first component to perform preliminary filtering on incoming signals.
2Ease of operation
If the filtering component is placed far from the shielding, then the installation is easier, but the filtering effectiveness is reduced due to longer exposure to noise
Solution Approach 1:
The first filtering component performs preliminary filtering action on the signal path before the signal enters the shielding. By placing this component outside the shielding at a convenient location, the patent enables easy installation while still providing effective noise reduction. The preliminary filtering reduces the noise burden on the second component inside the shielding, thus resolving the contradiction between installation ease and filtering effectiveness.
3Device complexity
If the capacitive component is placed outside the shielding, then the filtering unit is simpler to install, but high-frequency disturbances are not effectively directed to ground
Solution Approach 1:
The patent applies local quality by placing the capacitive component specifically inside the shielding where the electromagnetic environment is controlled. This localized placement ensures that the capacitive component can effectively direct high-frequency disturbances to ground without being affected by external electromagnetic interference. The different locations of the two filtering components reflect the principle of local quality, with each component optimized for its specific position in the electromagnetic environment.
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 enhances the filtering efficiency by minimizing exposure to external noise, ensuring the analog subassembly operates effectively by directing high-frequency disturbances to ground and maintaining signal integrity.
Implementation Method 1
the filter unit comprises a capacitive component implanted under the shielding and connected to an analog ground
Implementation Method 2
the analog subassembly is protected by a shield implanted on one face of the electronic card
Implementation Method 3
the filter unit further comprises a component filter placed at the input of the filter unit in series on the signal path passing through the shielding or in the immediate vicinity of the outside of the shielding
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2d
AI summary
An electronic device is proposed comprising a circuit board on which an analog subassembly and a filtering unit are mounted. The analog subassembly includes one or more analog radio frequency components for receiving radio frequency signals. The analog subassembly is protected by a shield mounted on one side of the circuit board. The filtering unit is mounted on the same side of the circuit board on a signal path electrically connected to the analog subassembly. The filtering unit includes a capacitive component mounted under the shielding and connected to an analog ground. The filtering unit also includes a filtering component placed at the input of the filtering unit in series on the signal path through the shielding or in the immediate vicinity of the outer edge of the shielding.