Optical Module Impedance Matching for High-Speed Signal Transmission
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In high-speed optical communication systems, semiconductor optical modulation elements face challenges with impedance matching due to parasitic capacitances, resistances, and inductances, leading to band deterioration and signal reflection issues, particularly with coaxial type configurations where the line impedance is not matched to standard 50Ω, causing phase rotation and gain cancellation.
Innovation Solution
An optical module design featuring a metal stem with a coaxial lead pin and dielectric filling, combined with a terminal matching circuit comprising a series resistor and parallel resistor-capacitor configuration, to supply high-frequency signals while minimizing band degradation from multiple reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a coaxial type semiconductor optical modulation device is used for high speed communication, then high frequency signal transmission is enabled, but impedance matching becomes difficult due to parasitic capacitances, resistances, and inductances
Solution Approach 1:
The patent changes the impedance parameter from the conventional 50Ω to a lower value (20Ω to 30Ω) that matches the characteristic impedance of the metal stem penetration section. This parameter adjustment resolves the impedance mismatch problem caused by parasitic elements at high frequencies, enabling better signal transmission without reflection.
2Shape
If the line impedance is 20Ω to 30Ω due to glass and lead pin diameter restrictions, then the coaxial structure is maintained, but it cannot be matched with general 50Ω standard
Solution Approach 1:
The patent applies different impedance values to different sections of the transmission path. The metal stem penetration section uses 20Ω to 30Ω impedance matching the coaxial structure, while the terminal matching circuit uses 50Ω to match standard equipment. This local differentiation allows both coaxial structure maintenance and standard compatibility.
Solution Approach 2:
The patent introduces an impedance transformation section as an intermediary between the 20Ω to 30Ω coaxial line and the 50Ω terminal. This intermediary component gradually transforms the impedance, preventing signal reflection while maintaining compatibility with standard 50Ω equipment.
3Speed
If electrical signal penetrates through metal stem, then signal transmission is achieved, but signal reflection occurs at penetration point causing band deterioration
Solution Approach 1:
The patent changes the impedance parameter of the metal stem penetration section to 20Ω to 30Ω, which matches the characteristic impedance of the coaxial structure. This parameter matching eliminates impedance discontinuity at the penetration point, preventing signal reflection and band deterioration while maintaining efficient signal transmission.
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
The optical module effectively supplies high-frequency signals up to higher frequencies while suppressing band degradation and improving frequency response characteristics by matching impedance and reducing signal reflections.
Implementation Method 1
a dielectric member is provided to fill the penetration hole around the outer circumference of the lead pin
Implementation Method 2
the terminal matching circuit is configured by a series connecting body which is comprised of a first resistor and a parallel body which is comprised of a second resistor and a capacitor
Data Source
AI summary
Provided is an optical module comprising a plate-like metal stem and a semiconductor optical modulation element mounted to a dielectric substrate provided on one side of the metal stem, wherein the metal stem has a metal stem penetration section in which a metal lead pin is inserted coaxially in a penetration hole which is formed in the metal stem and a dielectric member is provided to fill the penetration hole around the outer circumference of the lead pin, and a signal for modulation is supplied to the semiconductor optical modulation element connected in parallel with a terminal matching circuit, from the other side of the metal stem via the metal stem penetration section, wherein the terminal matching circuit is configured by a series connecting body which is comprised of a first resistor and a parallel body which is comprised of a second resistor and a capacitor.