Optical Coupling Device High Frequency Transmission
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Solution Overview
Problem
Conventional optical coupling devices face challenges in maintaining good high frequency current transmission characteristics, particularly at higher frequencies due to issues like insertion loss and leakage, which affect the efficiency of high frequency current control.
Innovation Solution
The optical coupling device design incorporates a light receiving element, a light emitting element, MOSFETs, and electrode plates with a sealing member, where the MOSFETs are strategically positioned and connected to minimize inductance and leakage, and the use of an insulating film instead of a metal plate under the light receiving element reduces parasitic capacitance and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional optical coupling device structure is used, then the device can transmit high frequency current, but insertion loss increases and leakage occurs at frequencies above 10 GHz
Solution Approach 1:
The patent removes the metal plate that was conventionally placed beneath the light receiving element, extracting the source of parasitic capacitance and leakage. This extraction eliminates the harmful electromagnetic coupling between the metal plate and the light receiving element, thereby reducing insertion loss and improving high frequency transmission characteristics above 10 GHz
Solution Approach 2:
The patent introduces an insulating film as an intermediary layer between the light receiving element and the mounting substrate. This intermediary prevents direct electromagnetic coupling and reduces parasitic capacitance, serving as a mediator that blocks the harmful interaction while maintaining structural support and electrical isolation
2Area of stationary object
If electrode plates are placed close to the light receiving element for compact design, then device size is reduced, but leakage and parasitic capacitance increase
Solution Approach 1:
The insulating film serves as a mediator between the electrode plates and the light receiving element, allowing them to be positioned closer together for compact device size while preventing harmful electromagnetic coupling. The insulating film fills the space between these components, providing electrical isolation and reducing parasitic capacitance despite the reduced spacing
3Reliability
If MOSFETs are positioned to minimize inductance, then high frequency response is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality optimization by positioning the MOSFETs with their source regions adjacent to the light receiving element and configuring the electrode plates to create low-inductance current paths. This localized optimization of the MOSFET region minimizes parasitic inductance in the critical signal path, improving high frequency response without requiring complex changes to the entire device structure
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 enhances high frequency current transmission characteristics by reducing insertion loss and suppressing leakage, especially at frequencies above 10 GHz, thereby improving the overall efficiency of high frequency current control.
Implementation Method 1
a light emitting element 12 provided on the light receiving element 11
Implementation Method 2
a light receiving element 11 provided with a pair of output terminals 11a, 11b
Data Source
AI summary
An optical coupling device includes a light receiving element provided with a first output terminal and a second output terminal, a light emitting element provided on the light receiving element, a first switching element, a first electrode plate, and a sealing member. The first switching element is provided side by side on the light receiving element. A first main terminal and a control terminal are provided on an upper surface of the first switching element. A second main terminal is provided on a lower surface of the first switching element. The first main terminal is connected to the first output terminal. The control terminal is connected to the second output terminal. An upper surface of the first electrode plate is connected to the second main terminal. The sealing member covers the light receiving element, the light emitting element, and the first switching element.