ESD Protection Circuit Switching Capacitance to Block Gate Leakage
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Solution Overview
Problem
Conventional ESD protection circuits with metal-oxide-capacitance units featuring thin gate oxide layers experience significant gate leakage current, which disrupts normal operation and ESD protection functions in advanced CMOS semiconductor processes.
Innovation Solution
Incorporating a switch unit between the resistance unit and the capacitance unit, controlled by a driving unit to be in an un-conducting status during normal operation and a conducting status during ESD conditions, effectively isolating the capacitance unit and minimizing gate leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a thinner gate oxide layer is used in metal-oxide-capacitance units, then the area required is reduced, but gate leakage current increases
Solution Approach 1:
The patent extracts the harmful gate leakage current path by introducing a switch unit that disconnects the capacitance unit from the power rail during normal operation. The switch unit is positioned between the power rail and the capacitance unit, allowing the harmful leakage current to be isolated and removed from the operational circuit path.
Solution Approach 2:
The patent makes the connection between the power rail and capacitance unit dynamic by using a controllable switch unit that can transition between conducting and non-conducting states. During normal operation, the switch is off, isolating the capacitance unit. During ESD events, the switch turns on to provide protection, creating a dynamic adaptation to different operational conditions.
2Manufacturing precision
If a thinner gate oxide layer is used in metal-oxide-capacitance units, then manufacturing precision is improved, but circuit reliability deteriorates due to gate leakage current
Solution Approach 1:
The patent removes the harmful effect of gate leakage current from the circuit by extracting it through the switch unit mechanism. The switch unit disconnects the capacitance unit during normal operation, preventing leakage current from affecting circuit reliability while preserving the benefits of thin gate oxide layer manufacturing.
Solution Approach 2:
The switch unit acts as an intermediary element between the power rail and the capacitance unit. It mediates the connection by being open during normal operation to block harmful leakage current, and closed during ESD events to provide protection, thus reconciling the conflict between manufacturing precision and circuit reliability.
3Reliability
If the capacitance unit is always connected to provide ESD protection, then ESD protection is maintained, but gate leakage current disrupts normal operation
Solution Approach 1:
The patent implements dynamic control of the capacitance unit connection through the switch unit. The switch transitions from a static always-connected state to a dynamic state where it is open during normal operation to prevent leakage current, and closes during ESD events to provide protection. This dynamic behavior resolves the contradiction between continuous protection and normal operation.
Solution Approach 2:
The switch unit operates periodically, switching between conducting and non-conducting states based on operational conditions. During normal operation, it remains non-conducting to prevent leakage; during ESD events, it switches to conducting state to provide protection, creating a periodic action pattern that alternates between protection and normal operation modes.
Data Source
AI summary
The disclosure provides an ESD protection circuit. The ESD protection circuit comprises: a clamping unit, a driving unit, a resistance unit, a switch unit, and a capacitance unit. The clamping device is coupled between a first power source and a second power source. The driving unit is coupled between the clamping device and a reference node. The resistance unit is coupled between the first power source and the reference node. The switch unit is coupled to the driving unit via the reference node. The capacitance unit is coupled between the switch unit and the second power source. Under a normal operation condition, the driving unit controls the switch unit to be in an un-conducting status. Under an ESD condition, the driving unit controls the switch unit to be in a conducting status.