Photo Relay Vertical Layout for High-Frequency Signal Isolation
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Solution Overview
Problem
Existing photo relay devices face challenges in improving high-frequency signal transmission characteristics due to coupling capacitances and open stub effects, which deteriorate performance at both high and low frequencies, and require larger installation areas.
Innovation Solution
The photo relay device configuration includes a substrate with MOSFETs, a support base, a light receiving element, and a light emitting element disposed in a longitudinal direction, reducing coupling capacitances and wire lengths, thereby improving high-frequency transmission characteristics and allowing for a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light receiving element and light emitting element are disposed in a conventional layout, then the device structure is simple, but coupling capacitances and open stub effects deteriorate high-frequency signal transmission characteristics
Solution Approach 1:
The patent applies dimensionality change by transitioning from a planar layout to a three-dimensional stacked configuration. The light receiving element and light emitting element are disposed at different vertical levels on the substrate, with the light receiving element positioned at a first location and the light emitting element at a second location in the vertical direction. This spatial separation in the vertical dimension reduces coupling capacitances between signal lines while maintaining a compact footprint, thereby improving high-frequency signal transmission characteristics without significantly increasing device complexity.
2Reliability
If wire lengths are reduced to improve high-frequency transmission, then signal quality improves, but the device requires more compact arrangement which increases design complexity
Solution Approach 1:
The patent utilizes vertical stacking to reduce horizontal wire lengths. By positioning the light receiving element and light emitting element at different vertical levels, the signal paths become shorter and more direct, reducing the impact of open stub effects and improving high-frequency transmission characteristics. The vertical arrangement allows for more efficient wire routing with fewer vias and interconnects compared to planar layouts.
3Reliability
If coupling capacitances are minimized for better signal transmission, then high-frequency performance improves, but the device layout becomes more constrained
Solution Approach 1:
The patent achieves minimal coupling capacitances by separating signal lines in the vertical dimension rather than relying solely on horizontal spacing. The light receiving element and light emitting element are positioned at different vertical levels, allowing signal lines to be routed at different heights with reduced parasitic coupling. This vertical separation maintains layout flexibility while effectively minimizing coupling capacitances for improved 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
This configuration enhances high-frequency signal transmission beyond 1 GHz by minimizing coupling capacitances and open stub effects, while also reducing the device's size and electromagnetic interference.
Implementation Method 1
a light emitting element that is in contact with a third surface of the light receiving element facing the first direction
Implementation Method 2
a light receiving element that is in contact with a second surface of the support base facing the first direction
Data Source
AI summary
According to one embodiment, a semiconductor device includes: a substrate that has a first surface extending in a first direction and a second direction; a first metal oxide semiconductor field effect transistor (MOSFET) that is provided on the first surface of the substrate; a support base that is provided above the first surface of the substrate and extends in a third direction intersecting the first direction and the second direction; a light receiving element that is in contact with a second surface of the support base facing the first direction; and a light emitting element that is in contact with a third surface of the light receiving element facing the first direction.