Twin-Monaural Amplifier PCB Layout for Ground Loop Noise
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Solution Overview
Problem
Conventional twin-monaural amplifying devices suffer from noise reduction due to ground loops formed by grounded lines and signal lines, which degrade the Signal to Noise (S/N) ratio of audio signals when a magnetic field is generated near the ground loop.
Innovation Solution
The amplifying device employs a configuration where the first and second substrates, each with their respective ground lines and signal lines, overlap in planar view, reducing the area of the ground loop and minimizing noise interference by ensuring the substrates face each other with sufficient proximity without requiring additional space for components between them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If substrates are arranged side by side in conventional twin-monaural construction, then component placement is simplified, but ground loop area increases causing noise
Solution Approach 1:
The patent transitions from a planar side-by-side substrate arrangement to a three-dimensional stacked configuration where substrates are positioned above and below a shielding plate. This dimensional change reduces the ground loop area while maintaining manufacturing feasibility through vertical integration rather than horizontal expansion.
Solution Approach 2:
A shielding plate is introduced as an intermediary component between the two substrates. This shielding plate serves multiple functions: it provides a reference potential layer that breaks the ground loop, acts as a physical barrier between substrates, and maintains electrical isolation while enabling compact vertical stacking.
2Object-affected harmful factors
If substrates are placed close together to reduce ground loop area, then noise is reduced, but electrical interference between substrates increases
Solution Approach 1:
The shielding plate functions as an electromagnetic shield and intermediary layer between the two substrates. It provides electrical isolation and reference potential that prevents direct interference while allowing the substrates to be positioned in close proximity for compact construction and reduced ground loop area.
Solution Approach 2:
The shielding plate is configured to provide a uniform reference potential across the interface between substrates. By establishing an equipotential surface, it eliminates potential differences that would cause electrical interference while allowing close substrate spacing for noise reduction.
3Ease of manufacture
If additional space is provided between substrates for components, then component mounting is facilitated, but ground loop area increases causing noise
Solution Approach 1:
The patent resolves the space conflict by transitioning to vertical stacking in the third dimension. Components can be mounted on the surfaces of substrates and shielding plate without requiring horizontal spacing, as the vertical arrangement naturally provides separation while minimizing ground loop area.
Solution Approach 2:
The shielding plate is positioned within the space between the two substrates, creating a nested three-layer structure. This nested configuration maximizes space utilization, allowing components to be mounted on available surfaces without increasing the overall ground loop footprint.
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 reduces noise caused by ground loops, enhancing the S/N ratio by minimizing the area surrounded by the ground loop and maintaining close proximity between substrates without increasing electrical interference.
Implementation Method 1
In the event that a magnetic field is generated near the ground loop formed by the grounded lines and the signal lines, the magnetic field produces a current in the grounded loop. This phenomenon may cause reduction of S/N (Signal to Noise) ratio for audio signals.
Data Source
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AI summary
An amplifying device includes a first substrate and a second substrate. The first substrate has a first mounting surface, and the second substrate has a second mounting surface. The first mounting surface of the first substrate that is on the opposite side of the second substrate is provided with: a first ground line; a first signal line configured to transfer an audio signal; and a first amplifier configured to amplify the audio signal. The second mounting surface of the second substrate that is on the opposite side of the first substrate is provided with: a second grounded line; a second signal line configured to transfer an audio signal; and a second amplifier configured to amplify the audio signal. The first grounded line and the second grounded line correspond to each other in their positions and shapes, and overlap in planar view. The first signal line and the second signal line correspond to each other in their positions and shapes, and overlap in planar view.