GaN Bilateral Switch Substrate Biasing for Back-Gating Control
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Solution Overview
Problem
Existing gallium nitride based bilateral switch power devices face issues with substrate voltage clamping and back gating phenomena, leading to imbalanced voltages and reduced conduction due to floating substrates, which conventional external circuits fail to address effectively.
Innovation Solution
An integrated bilateral switch power device with a substrate bias RC network that electrically couples the substrate node to conduction contact regions, maintaining the substrate voltage at a minimum potential, thereby stabilizing the device operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the substrate is left floating to avoid clamping to minimum voltage, then the device structure is simpler, but back gating phenomenon occurs causing intermediate voltage and voltage imbalance
Solution Approach 1:
The patent introduces an intermediate substrate contact structure that couples the substrate to both source terminals through resistive paths. This intermediary connection allows the substrate to act as a voltage reference without being directly clamped to minimum voltage, preventing back gating while maintaining voltage balance through the resistive mediation of the substrate contacts.
Solution Approach 2:
The patent changes the electrical parameters of the substrate connection by introducing specific resistance values in the substrate contact paths. By controlling the resistance parameters of the substrate contacts, the system achieves optimal voltage distribution and prevents back gating phenomenon while maintaining structural simplicity.
2Reliability
If external circuits are used to couple the substrate to the voltage which is each time lower in the device, then voltage balance is improved, but device complexity and synchronization speed are reduced
Solution Approach 1:
The patent merges the substrate biasing function into the intrinsic device structure by integrating substrate contacts directly with the semiconductor layers. This combination eliminates the need for separate external biasing circuits, achieving voltage balance through the device's own structural elements while maintaining high synchronization speed.
Solution Approach 2:
The device structure itself provides the substrate voltage reference function through integrated substrate contacts that automatically couple to the lower voltage source terminal. The system serves itself by using its own structural components rather than requiring external assistance, achieving both voltage balance and high speed operation.
3Stability of the object's composition
If the substrate is clamped to minimum voltage, then voltage reference is stable, but the substrate cannot adapt to switching operations where source terminals alternate voltages
Solution Approach 1:
The patent creates a dynamic substrate voltage reference system where the substrate voltage automatically adapts to the lower voltage source terminal through resistive coupling. This dynamic behavior allows the substrate to maintain a stable reference relative to the active switching terminal while adapting to voltage alternations during switching operations.
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 solution ensures stable substrate voltage clamping, preventing back gating and maintaining efficient conduction by synchronizing the substrate voltage with the lowest conduction potential, enhancing device performance and speed.
Implementation Method 1
substrate bias RC network configured to electrically couple the substrate node selectively to the first and the second conduction contact regions
Implementation Method 2
substrate bias RC network configured to electrically couple the substrate node selectively to the first and the second conduction contact regions
Data Source
AI summary
An integrated bilateral switch power device is based on gallium nitride, formed in a die having a semiconductor body integrating a first and a second field effect transistor. The semiconductor body has a semiconductor substrate and a layer stack based on gallium nitride. The layer stack is superimposed on the substrate and forms a channel region and a first and a second gate region arranged side by side and at a mutual distance above the channel region. The substrate is electrically coupled to a substrate node. A first and a second conduction contact region are arranged side by side and at a mutual distance on opposite sides of the channel region and a substrate bias RC network is configured to electrically couple the substrate node selectively to the first and the second conduction contact regions which is at a minimum potential.