Trench MOS Transistor Adaptive Capacitance for Noise Immunity
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Solution Overview
Problem
Trench MOS transistors face challenges with electromagnetic susceptibility (EMS) due to their susceptibility to noise, which can cause incorrect switching between on and off states, especially in noisy environments, and existing solutions either consume additional chip area or increase component count.
Innovation Solution
The integration of additional capacitance and a switchable resistance between the gate and source terminals of the trench MOS transistor, allowing dynamic adaptation of capacitance to improve EMS across a broader frequency spectrum without requiring additional chip area or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional capacitance is integrated between gate and source, then electromagnetic susceptibility (EMS) is improved, but device complexity increases
Solution Approach 1:
The patent merges the additional capacitance function with the existing gate structure by forming the capacitance between the gate electrode and source region using existing trench structures and dielectric materials. This integration approach improves EMS without adding separate discrete components, thereby avoiding increased device complexity.
Solution Approach 2:
The gate structure is given multiple functions: it serves both as the control electrode for transistor switching and as one plate of the additional capacitance. The trench structure similarly serves both as the transistor architecture and as part of the capacitance formation. This multi-functionality improves EMS while maintaining simple device structure.
2Reliability
If switchable resistance is added between gate and source, then immunity to low frequency noise is improved, but manufacturing complexity increases
Solution Approach 1:
The switchable resistance is integrated into the existing transistor fabrication process by forming the resistive element within the trench structure or as part of the gate assembly. The resistance switch functionality is incorporated using standard semiconductor processing techniques, avoiding the need for separate discrete resistance components and simplifying manufacturing.
3Reliability
If dynamic capacitance adjustment is implemented, then EMS across broader frequency spectrum is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements dynamic capacitance adjustment by making the additional capacitance switchable, allowing it to be connected or disconnected based on operating conditions. The capacitance can be dynamically adjusted to provide optimal EMS protection across different frequency ranges while maintaining simple control through standard switching mechanisms.
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 approach enhances the transistor's immunity to both high and low frequency noise by dynamically adjusting the gate-to-source capacitance ratio, effectively reducing EMS without increasing costs or complexity.
Implementation Method 1
A capacitor is coupled between the gate and source of the transistor. The capacitor is dynamic such that the capacitor can be switched between an integrated state in which the capacitance is between the gate and source and a disconnected state in which the capacitance is not between the gate and source.
Implementation Method 2
A resistor is selectively coupled by a second switch between the gate and source of the transistor such that immunity to low frequency noise is improved.
Data Source
AI summary
A circuit includes a transistor having a source, drain, a gate, and an electrode structure. A source terminal is coupled to the source. A drain terminal coupled to the drain. Terminals are coupled to the gate and to the electrode structure. A switch is coupled to the source, the gate terminal and the electrode terminal to selectively couple one of the gate and electrode structure to the source. In further embodiments, a second switch is used to selectively couple a resistor between the gate and the source. A method is used to control the switches to keep the transistor in an off state or allow it to switch to an on state.