Optical Transmitter Interconnecting Circuit Board Impedance Matching
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Solution Overview
Problem
Conventional interconnecting circuit boards for optical transmitters suffer from degraded electrical signal reflection characteristics, particularly at high-frequency applications, due to wide spacing between electrode pads which increases impedance mismatch.
Innovation Solution
The interconnecting circuit board design includes a coplanar waveguide and microstrip line with a narrower signal wiring line and reduced spacing between the signal and ground wiring lines, maintaining ease of mounting while improving impedance matching and reflection characteristics by reducing impedance mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wide spacing is provided between electrode pads for ease of surface mounting, then ease of manufacture is improved, but impedance matching deteriorates and reflection characteristics degrade
Solution Approach 1:
The patent applies local quality by creating a transition region where the spacing between signal and ground wiring lines gradually changes from wide (for ease of mounting) to narrow (for impedance matching). This is achieved by extending the ground wiring line to overlap with the signal wiring line in a transition section, providing different spacing characteristics in different locations along the same connection path.
2Ease of manufacture
If wide spacing is provided between electrode pads, then ease of manufacture is improved, but electrical signal reflection characteristics deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-designing the transition section with gradual spacing change before the final narrow spacing region. This gradual transition prepares the electromagnetic field for the impedance change, preventing sudden reflections that would occur with abrupt spacing changes, thereby improving reflection characteristics while maintaining ease of manufacture.
3Reliability
If narrow spacing is provided between signal and ground wiring lines, then impedance matching is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the wiring line structure into distinct sections: a first section with wide spacing for ease of mounting, a transition section with gradually changing spacing, and a second section with narrow spacing for impedance matching. This segmentation allows each section to optimize for its specific function without compromising the others.
Data Source
AI summary
An optical transmitter including: an optical module; an interconnecting circuit board configured to be electrically coupled to the optical module; and a printed circuit board configured to be electrically coupled to the interconnecting circuit board; wherein the interconnecting circuit board includes: a coplanar waveguide; and a microstrip line including a signal wiring line extended from an end of the coplanar waveguide and a ground wiring line, wherein the width of the signal wiring line is narrower than the width of a signal wiring line of the coplanar waveguide, and the spacing between the signal wiring line extended from the end of the coplanar waveguide and the ground wiring line is smaller than the spacing between the signal wiring line of the coplanar waveguide and the ground wiring line.