FPC-Attached Optical Modulator Impedance Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Impedance mismatch at the connection points between lead pins and conductor patterns in optical modulators leads to electromagnetic radiation and crosstalk, deteriorating high-frequency characteristics such as eye pattern extinction ratio and jitter in optical transmission systems.
Innovation Solution
Incorporating a conductive extension portion along the length of lead pins on the relay substrate, which extends to include the connection points, and is electrically connected to the housing, to adjust and maintain the characteristic impedance of the connection regions, thereby reducing impedance mismatch and electromagnetic radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If lead pins are directly connected to conductor patterns on the relay substrate, then the device structure is simple, but impedance mismatch occurs causing electromagnetic radiation and crosstalk
Solution Approach 1:
A connection portion is introduced as an intermediary structure between the lead pin and the conductor pattern on the relay substrate. This connection portion includes a first conductor pattern on the lead pin side and a second conductor pattern on the relay substrate side, which are coupled together. This intermediary structure enables impedance matching and reduces electromagnetic radiation by providing a controlled transition zone for the high-frequency signal.
2Object-generated harmful factors
If the connection portion structure is added to reduce impedance mismatch, then electromagnetic radiation is suppressed, but the device complexity increases
Solution Approach 1:
The connection portion is designed with specific impedance parameters to match the lead pin impedance with the conductor pattern impedance on the relay substrate. By carefully controlling the geometry, material, and dimensions of the connection portion conductors, the characteristic impedance is optimized to minimize reflections and reduce crosstalk between adjacent lead pins.
3Volume of moving object
If lead pins are positioned close together to reduce housing size, then the modulator is downsized, but impedance control becomes difficult leading to increased electromagnetic interference
Solution Approach 1:
The connection portion serves as a controlled intermediary that enables precise impedance matching even when lead pins are positioned close together. The structured design of the connection portion allows for independent impedance control of each lead pin connection, maintaining signal integrity and reducing crosstalk despite the compact spacing.
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 configuration effectively suppresses noise and crosstalk, maintaining stable high-frequency characteristics and preventing deterioration of optical modulation performance by ensuring impedance matching and shielding the connection areas.
Implementation Method 1
adjust and maintain the characteristic impedance of the connection regions, thereby reducing impedance mismatch
Implementation Method 2
shielding the connection areas
Data Source
AI summary
An optical modulator includes: an optical modulation element which is accommodated in a housing and has a signal electrode; a lead pin for inputting a high-frequency signal; a relay substrate in which a conductor pattern which electrically connects the lead pin and the signal electrode is formed; and a conductive extension portion which extends along a length direction of the lead pin in a range which includes at least a position of a connection portion between the lead pin and the conductor pattern, in which the extension portion is electrically connected to the housing.