Optical Module Protrusion Ground Pin Crosstalk Reduction
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Solution Overview
Problem
High-frequency electrical signals in optical modulators experience crosstalk due to close proximity of wiring patterns on Flexible Printed Circuits (FPC) units, leading to degraded signal characteristics, and existing solutions like enlarging pattern distance or forming large ground patterns either increase size or reduce flexibility.
Innovation Solution
Incorporating protrusion ground pins with a larger cross-sectional size than signal pins, positioned between signal pins to act as a barrier, reducing crosstalk without increasing the FPC unit's size or compromising flexibility by eliminating the need for a full ground pattern on the FPC unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If wiring patterns are positioned close to each other on the FPC unit, then the apparatus size is kept compact, but crosstalk occurs between transfer paths degrading signal characteristics
Solution Approach 1:
A ground pattern is introduced as an intermediary element between adjacent signal wiring patterns on the FPC unit. This ground pattern acts as a mediator that shields the signal lines from each other, reducing crosstalk through electromagnetic field isolation while allowing the wiring patterns to remain in close proximity for compact design
Solution Approach 2:
The ground pattern is selectively positioned only in critical areas where crosstalk is most likely to occur between adjacent signal lines, rather than covering the entire FPC unit. This localized approach reduces crosstalk effectively while minimizing the impact on FPC flexibility and overall size
2Object-affected harmful factors
If the distance between wiring patterns is enlarged to reduce crosstalk, then signal characteristics improve, but the FPC unit size increases
Solution Approach 1:
The ground pattern serves as a shielding intermediary that enables signal lines to be positioned closer together without suffering from crosstalk. This eliminates the need to increase spacing between wiring patterns, thereby preventing FPC unit size enlargement while still achieving effective crosstalk reduction
3Object-affected harmful factors
If a ground pattern is formed in a large area to reduce crosstalk, then signal integrity improves, but the FPC unit flexibility and pliability are impaired
Solution Approach 1:
The ground pattern is applied locally only in specific regions where crosstalk protection is most needed, rather than covering the entire FPC unit surface. This localized ground pattern approach provides sufficient electromagnetic shielding to reduce crosstalk while leaving other areas of the FPC flexible and pliable for bending and routing
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
Significantly reduces crosstalk at the connecting section, thereby improving the overall signal integrity of high-frequency signals transferred through the FPC unit, while maintaining the compact size and flexibility of the optical module.
Implementation Method 1
crosstalk may occur between the transfer paths. In other words, when the plurality of wiring patterns are printed on the FPC unit, if the wiring patterns are positioned close to each other, a problem arises where the crosstalk occurs
Data Source
AI summary
An optical module includes: an optical modulator that includes a plurality of electrodes and that performs an optical modulation process by using electrical signals input to the electrodes; and a flexible substrate that has flexibility and has a plurality of wiring patterns used for transferring the electrical signals each of which is input to a different one of the electrodes. The optical modulator includes: a plurality of connecting members that connect together the electrodes and the wiring patterns; and at least one protrusion that has a ground voltage, is connected to the flexible substrate while being positioned on a line segment connecting together two of the connecting members positioned adjacent to each other, and has a cross section of which the size measured in the direction perpendicular to the line segment is larger than the size of the cross section of each of the connecting members.