ESD Protection Circuit with Pin-Specific Trigger and Active Clamp
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ESD protection circuits face inefficiencies due to high voltage margins and area consumption, particularly when dealing with multiple voltage ranges and the need for stacking protection devices, which complicates design and increases silicon area requirements.
Innovation Solution
An ESD protection circuit with a single, voltage-triggered active clamp and a pin-specific trigger circuit using zener diodes to match clamp voltage to the maximum supply voltage, combined with scalable transistors for adjustable breakdown voltages and resistances, minimizing transistor breakdown voltage and circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If snapback-based ESD protection devices are stacked to achieve higher hold voltage above maximum supply voltage, then ESD protection capability is improved, but the difference between trigger voltage and hold voltage increases, requiring higher breakdown voltage components and increasing silicon area
Solution Approach 1:
The patent changes the fundamental operating parameter from snapback behavior to active clamp behavior. Instead of relying on the inherent snapback characteristics of protection devices T1-T4, the invention introduces a separate trigger circuit that actively clamps the voltage at a predetermined level VC. This allows precise control of the clamp voltage to match the maximum supply voltage, eliminating the need for large voltage margins and reducing the required breakdown voltage of components, thereby reducing silicon area.
2Measurement precision
If multiple ESD protection devices are stacked to achieve pin-specific trigger and hold voltage levels, then protection precision for specific pins is improved, but device complexity and design difficulty increase
Solution Approach 1:
The patent segments the ESD protection function into two independent parts: a central active clamp circuit that provides the voltage clamping function, and separate trigger circuits for each pin that detect ESD events. This segmentation allows each pin to have its own trigger threshold while sharing the common clamp circuit, achieving pin-specific protection without the complexity of stacking multiple protection devices for each pin.
Solution Approach 2:
The active clamp circuit serves as a universal protection mechanism that can protect multiple pins simultaneously. The single clamp circuit with voltage VC can handle ESD events from any pin, while the trigger circuits provide pin-specific detection. This multi-functional approach reduces overall device complexity compared to having separate protection paths for each pin.
3Reliability
If voltage margin between maximum supply voltage and ESD hold voltage is increased, then safety margin is improved, but transistor breakdown voltage requirements increase, leading to larger device area
Solution Approach 1:
The patent implements a dynamic protection mechanism where the clamp voltage VC is actively maintained at a predetermined level that can be precisely matched to the maximum supply voltage. Unlike static snapback circuits with fixed trigger and hold voltages, the active clamp dynamically responds to ESD events and maintains the voltage at the optimal level, allowing minimal safety margin without compromising protection effectiveness, thereby reducing device area.
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 solution allows for accurate matching of clamp voltage to the maximum supply voltage, reducing voltage margins and area consumption, while enabling effective ESD protection with minimal transistor breakdown voltage and circuit area, suitable for integrated circuits with multiple voltage ranges.
Implementation Method 1
a trigger circuit (1) being connected to the at least one pin and providing pin specific trigger voltages
Implementation Method 2
an ESD protection device, preferably being configured as a transistor, which is connected between the first and second supply line... capable of conducting current from the first supply line to the second supply line
Implementation Method 3
a trigger circuit (1) being connected to the at least one pin and providing pin specific trigger voltages
Data Source
AI summary
An ESD protection circuit comprises a first supply line (VDD), a second supply line (Vss), an ESD protection device, preferably being configured as a transistor (MP), which is connected between the first and second supply line (VDD, VSS) and at least one pin (VA) connected to the first and second supply lines (VDD, VSS) via diodes D1, D2. The ESD protection device is controllable by a trigger voltage that is set by a trigger voltage setting circuit (RP, RD, Z1, Z2, Z3). The ESD protection circuit comprises a trigger circuit (1) being connected to the at least one pin (VA) and providing pin specific trigger voltages, wherein the trigger circuit (1) is further connected to the trigger voltage setting circuit.