Bidirectional Switch Passive Network for Substrate Potential Stability
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Solution Overview
Problem
Bidirectional switches face capacitive coupling issues due to the absence of a single reference potential terminal, leading to reliability and stability problems, as conventional solutions with substrate contacts are not applicable.
Innovation Solution
A semiconductor device with a passive electrical network that includes capacitors connected to current-controlled switching devices, allowing temporary electrical connection of the substrate region to input-output terminals based on voltage polarity, using self-biasing to generate control signaling without external biasing signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple electrical contact is used to tie the substrate to a reference potential in a bidirectional switch, then the device structure remains simple, but the reliability and stability deteriorate due to capacitive coupling between the floating substrate and the channel
Solution Approach 1:
The patent introduces a substrate contact structure with multiple contact regions (first substrate contact region and second substrate contact region) that act as intermediaries between the substrate and the channel. These contact regions are selectively connected to different input-output terminals based on voltage polarity, mediating the capacitive coupling issue by providing controlled electrical connection paths rather than a simple fixed contact.
Solution Approach 2:
The substrate contact structure dynamically changes its electrical connection state based on the voltage polarity applied to the bidirectional switch. When the first input-output terminal is at a higher potential, the first substrate contact region connects to the substrate; when the second input-output terminal is at a higher potential, the second substrate contact region connects. This dynamic adaptation resolves the capacitive coupling problem while maintaining structural integration.
2Reliability
If conventional substrate contact solutions are applied to bidirectional switches, then the reference potential stability is improved, but the solution becomes more complex and less cost-effective
Solution Approach 1:
The patent merges the substrate contact function with the existing bidirectional switch structure by integrating the first and second substrate contact regions directly into the device architecture. These contact regions are formed as part of the semiconductor structure and are selectively connected through the drift region, combining multiple functions into a unified integrated solution rather than adding separate discrete components.
Solution Approach 2:
The substrate contact structure serves multiple functions: it provides reference potential stabilization, manages capacitive coupling, and adapts to bidirectional voltage polarity changes. The same structural elements (substrate contact regions, drift region connections) perform both the substrate biasing function and the voltage-polarity-dependent switching function, reducing overall device complexity.
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 solution effectively alleviates capacitive coupling issues by providing necessary control signaling for switching devices, ensuring reliable operation and integrating into a single integrated circuit, offering a simpler and cost-effective solution compared to discrete component-based approaches.
Implementation Method 1
A passive electrical network includes a first capacitance and a second capacitance. The first capacitance is connected between a control terminal of the second switching device and the first input-output terminal. The first capacitance is configured to supply a temporary current to the control terminal of the second switching device during a transition of the bidirectional switch from a blocking state to a conducting state
Implementation Method 2
The second capacitance is connected between a control terminal of the first switching device and the second input-output terminal. The second capacitance is configured to supply a temporary current to the control terminal of the first switching device during a transition of the bidirectional switch from a blocking state to a conducting state at a second voltage polarity
Implementation Method 3
A bidirectional switch is formed in the semiconductor body and is configured to control current flow in both directions. The bidirectional switch includes first and second gate structures that are each configured to control a conductive state of an electrically conductive channel
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A device includes a semiconductor body having an active region and a substrate region that is beneath the active region. A bidirectional switch is formed in the semiconductor body having first and second gate structures that are configured to block voltage across two polarities as between first and second input-output terminals that are in ohmic contact with the electrically conductive channel. First and second switching devices are configured to electrically connect the substrate region to the first and second input-output terminals, respectively. A passive electrical network includes a first capacitance connected between a control terminal of the first switching device and the second input-output terminal and a second capacitance connected between a control terminal of the second switching device and the first input-output terminal. The passive electrical network is configured temporarily electrically connect the substrate region to the first and second input-output terminal at different voltage conditions.