Decoupling Capacitance Circuit for Thin-Oxide MOSFET Protection
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Solution Overview
Problem
Existing semiconductor devices face challenges in effectively decoupling functional circuits from voltage variations due to variations in reference voltages, leading to potential breakdown of thin gate oxides and increased current leakage in MOSFETs, particularly in high-frequency applications.
Innovation Solution
Incorporating a decoupling capacitance system with a decap circuit and a bias circuit, where the decap circuit is coupled in series with a self-bias or boosted bias circuit, using thin-oxide MOSFETs to reduce voltage drops and minimize gate oxide breakdown and current leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If thin-oxide MOSFETs are used to reduce device area, then area is reduced, but susceptibility to breakdown and leakage increases
Solution Approach 1:
A decoupling capacitance system is introduced as an intermediary component between the power supply and the thin-oxide MOSFET circuitry. This capacitance system absorbs voltage variations and prevents them from reaching the MOSFETs, thereby protecting them from breakdown and leakage while allowing the use of thin-oxide devices for area reduction.
Solution Approach 2:
The decoupling capacitance is positioned beforehand in the circuit to cushion against voltage variations before they can affect the thin-oxide MOSFETs. By placing the capacitance close to the MOSFETs and configuring it with appropriate values, the system prepares a protective buffer that absorbs potential harmful voltage swings in advance.
2Reliability
If decoupling capacitance is increased to protect against voltage variations, then protection is improved, but device area increases
Solution Approach 1:
The patent optimizes the capacitance value parameters to achieve the minimum required protection while minimizing area. By carefully selecting capacitance values based on the specific voltage variation characteristics and circuit requirements, the design achieves effective protection without unnecessarily increasing the decoupling capacitance size.
Solution Approach 2:
The decoupling capacitance is strategically placed locally near the thin-oxide MOSFETs that require protection, rather than using a single large capacitor elsewhere in the circuit. This local placement provides targeted protection to the vulnerable components while minimizing the overall area occupied by the decoupling system.
3Reliability
If series bias circuit is added to reduce voltage drops, then voltage control is improved, but device complexity increases
Solution Approach 1:
The bias circuit is configured to automatically adjust and maintain appropriate voltage levels without requiring external control circuitry. The series bias circuit uses the inherent characteristics of the decoupling capacitance and power supply to self-regulate the voltage drops, providing improved voltage control while avoiding additional complexity from external control 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
The solution provides effective capacitive decoupling, reducing the susceptibility of thin-oxide MOSFETs to breakdown and leakage, while maintaining a relatively small footprint and current consumption, suitable for both low and high-frequency applications.
Implementation Method 1
Incorporating a decoupling capacitance system with a decap circuit and a bias circuit
Data Source
AI summary
A semiconductor device includes: a decoupling capacitance system configured to decouple voltage variations in a first voltage drop between a first reference voltage rail and a second reference voltage rail, the decoupling capacitance system including: a decoupling capacitance circuit; and a filtered biasing circuit, wherein an unswitched series electrical connection couples the decoupling capacitance circuit and the filtered biasing circuit between the first reference voltage rail and the second reference voltage rail.