Thin-Oxide MOSFET Protection Using Thick-Oxide Clamps
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Solution Overview
Problem
Thin-oxide metal-oxide-semiconductor field-effect transistors (MOSFETs) in data converters face challenges in over-voltage protection due to varying power sequences in VLSI designs, where common solutions like diode clamps may compromise high linearity requirements.
Innovation Solution
An electrical circuit with a thick-oxide MOSFET clamp circuit and an adaptive voltage reference circuit is used to protect thin-oxide MOSFETs from high voltages, ensuring over-voltage protection while maintaining high linearity by biasing the clamp circuit with an adaptive reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diode clamps are used in power domain interfaces, then over-voltage protection is provided, but linearity is compromised
Solution Approach 1:
The patent introduces thick-oxide MOSFETs as intermediary protection devices between power domains. These MOSFETs function as voltage clamps that activate only during over-voltage conditions, providing protection without interfering with normal signal operation. The thick-oxide structure enables these devices to withstand higher voltages while maintaining low capacitance, thus preserving signal linearity in the data converter path.
2Use of energy by moving object
If different voltages are used to power different circuit segments, then power consumption is reduced, but over-voltage protection challenges arise
Solution Approach 1:
The patent applies different oxide thicknesses to different MOSFETs based on their specific functional requirements. Thick-oxide MOSFETs are used specifically for protection functions where high voltage tolerance is needed, while thin-oxide MOSFETs are used in signal paths where low capacitance and high speed are critical. This localized differentiation allows each device to be optimized for its specific role, enabling multi-voltage operation with built-in protection.
3Device complexity
If power sequence is controlled externally, then power management is simplified, but adaptability to different power sequences is reduced
Solution Approach 1:
The protection circuit is designed to automatically adapt to different power sequences without requiring external control. The thick-oxide MOSFET clamps are biased to activate at specific voltage thresholds, enabling them to self-regulate protection based on the actual power-up or power-down sequence occurring in the system. This self-adaptive behavior eliminates the need for complex external power management control while maintaining protection across various scenarios.
Data Source
AI summary
One embodiment features an electrical circuit comprising: a high-voltage input configured to receive a high voltage into the electrical circuit; a low-voltage input configured to receive a low voltage into the electrical circuit; a thin-oxide circuit comprising a thin-oxide metal-oxide-semiconductor field-effect transistor (MOSFET); and a protection circuit configured to protect the thin-oxide circuit from the high voltage, wherein the protection circuit comprises a thick-oxide MOSFET clamp circuit, and an adaptive voltage reference circuit configured to provide an adaptive reference voltage, wherein the thick-oxide MOSFET clamp circuit is biased by the adaptive reference voltage.