Impedance Controlled Signal Traces in Portable Devices
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Solution Overview
Problem
Portable electronic devices face challenges in minimizing size and thickness due to the number and placement of electronic components, which affects the control of electrical impedances and signal trace configurations, leading to inefficiencies in signal transmission and noise reduction.
Innovation Solution
An electrical assembly with a conductive chassis acting as a ground plane, integrated dielectric layers, and signal traces, which eliminates the need for a lower ground layer and reduces the overall thickness while maintaining electrical parameters, using a flexible printed circuit board with a microstrip, embedded microstrip, or stripline circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional multi-layer PCB structures with separate ground layers are used, then electrical impedance control is achieved, but device thickness increases
Solution Approach 1:
The patent combines the ground plane function with the chassis structure itself, merging two separate elements (chassis and ground layer) into one integrated component. This eliminates the need for a separate lower ground layer while maintaining electrical impedance control through the integrated chassis-ground configuration.
Solution Approach 2:
The chassis is designed to serve multiple functions simultaneously: it provides structural support, acts as a ground plane for electrical impedance control, and serves as a mounting structure for electronic components. This multi-functionality reduces the need for separate dedicated ground layers.
2Adaptability or versatility
If more electronic components are added to increase device functionality, then device capabilities improve, but device size and thickness increase
Solution Approach 1:
The patent utilizes the vertical dimension by embedding signal traces within dielectric layers and using the chassis as a ground plane, allowing for compact component arrangement in three-dimensional space rather than spreading components out in two dimensions, thus reducing overall device volume.
Solution Approach 2:
The patent employs a nested structure where dielectric layers with embedded signal traces are positioned between the chassis and the flexible printed circuit board, creating a compact multi-layer configuration that maximizes space utilization and reduces device volume.
3Reliability
If signal traces are routed through multiple layers to achieve impedance control, then signal integrity is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the lower ground layer from the traditional multi-layer PCB structure, simplifying the manufacturing process by reducing the number of layers that need to be manufactured and assembled, while maintaining signal integrity through the alternative chassis-based ground configuration.
Data Source
AI summary
An electrical assembly having controlled impedance signal traces and a portable electronic device comprising an electrical assembly having controlled impedance signal traces are provided. In accordance with one embodiment, there is provided a portable electronic device, comprising an electrical assembly, comprising: a chassis made from a conductive material and forming a first ground plane; a first dielectric substrate layer overlaying the chassis; a first signal trace overlaying the first dielectric substrate layer; and a second dielectric layer overlaying the first signal trace.