Optical PCB Layout With VCSEL-TIA Link for Shorter Copper Traces
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Solution Overview
Problem
Existing interconnection technologies face challenges in providing high bandwidth, low power consumption, and reliability while managing increased data traffic, leading to significant signal and power losses due to lengthy copper traces in printed circuit boards (PCBs) connecting transceivers to switch ICs.
Innovation Solution
A PCB design that embeds a transceiver and optically connects it to a switch IC through a short copper trace, utilizing a substrate with insulating layers, wiring patterns, and a dielectric layer to reduce signal and power losses, featuring an optical sensing chip, transimpedance amplifier chip, and an optical connector to minimize electrical connection paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the transceiver is connected to the switch IC through a copper trace on the PCB, then electrical connection is established, but power loss and signal loss increase due to the length of the copper trace
Solution Approach 1:
The patent replaces the electrical connection mechanism (copper trace) with an optical connection mechanism (optical fiber). The transceiver includes an optical connector that couples to the optical fiber, eliminating the need for long copper traces on the PCB. This substitution of mechanical/electrical system with optical system resolves the contradiction by achieving electrical connection functionality through optical means, thereby reducing power loss without being constrained by trace length.
2Loss of energy
If the copper trace length is reduced to minimize power loss, then the transceiver must be placed very close to the switch IC, but this limits design flexibility and increases device complexity
Solution Approach 1:
By substituting the electrical copper trace connection with an optical fiber connection, the patent eliminates the constraint that requires the transceiver to be placed immediately adjacent to the switch IC. The optical connector on the transceiver couples to the optical fiber, allowing flexible PCB layout design while maintaining minimal power loss, thus resolving the contradiction between energy efficiency and design flexibility.
3Loss of energy
If optical connection is used instead of electrical connection, then power loss is reduced, but the device structure becomes more complex with additional components
Solution Approach 1:
The patent merges the optical connector with the transceiver housing, integrating the optical coupling mechanism directly into the transceiver structure. This consolidation reduces the number of separate components and simplifies the overall device structure, thereby resolving the contradiction between achieving low power loss through optical connection and maintaining device simplicity.
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 design effectively reduces signal and power losses by shortening the copper trace length, enhancing communication characteristics and reducing manufacturing costs through simplified packaging and reduced PCB size.
Implementation Method 1
an optical sensing chip including a vertical cavity surface emitting laser (VCSEL) and a photodiode
Implementation Method 2
an optical sensing chip including a vertical cavity surface emitting laser (VCSEL) and a photodiode
Data Source
AI summary
A printed circuit board (PCB) includes a substrate including a first insulating layer and first wiring patterns disposed on the first insulating layer, an optical sensing chip including a vertical cavity surface emitting laser (VCSEL) and a photodiode, disposed on the first insulating layer to be in contact with at least one of the first wiring patterns, a transimpedance amplifier (TIA) chip disposed to be spaced apart from the optical sensing chip on the first insulating layer and disposed to be in contact with at least one first wiring pattern, different from the first wiring pattern connected to the optical sensing chip, among the first wiring patterns, and a dielectric layer stacked on the substrate and having a hole exposing the VCSEL and the photodiode of the optical sensing chip. The optical sensing chip and the transimpedance amplifier chip are connected through a wiring pattern disposed on the dielectric layer.