Passive ESD Protection Circuit with Trigger Voltage Control
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Solution Overview
Problem
Conventional ESD protection circuits in integrated circuits often occupy valuable space, increase component count, and decrease reliability due to active shut-off circuitry, which can lead to false triggering and leakage paths, complicating design and testing while requiring additional protection against ESD events.
Innovation Solution
A passive trigger voltage controlled ESD protection circuit using a resistor, capacitor, and blocking diode to selectively conduct current during ESD events, preventing false triggering and reducing leakage by maintaining a high impedance during normal operation and increasing the trigger voltage only during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active shut-off circuitry is used to disable ESD protection during normal operation, then false triggering is reduced, but device complexity and component count increase
Solution Approach 1:
The patent extracts the active shut-off circuitry from the ESD protection system and replaces it with a passive RC circuit. The active transistor-based shut-off mechanism is removed entirely, leaving only the resistor-capacitor network to control the trigger voltage, thereby reducing device complexity while maintaining false triggering prevention
Solution Approach 2:
The patent substitutes the active electronic control system (transistors, logic circuits) with a passive electrical system (resistor-capacitor network). The active shut-off transistor is replaced by a passive RC circuit that naturally filters the trigger signal, replacing complex active control with simple passive components
2Ease of operation
If active shut-off circuitry is used to control ESD protection, then ESD protection can be disabled during normal operation, but leakage paths are introduced and reliability decreases
Solution Approach 1:
The patent uses a simple, inexpensive RC circuit instead of complex active shut-off circuitry. The passive components (resistor and capacitor) are basic, reliable elements that introduce no additional leakage paths, replacing the unreliable active control mechanism with a robust passive alternative
Solution Approach 2:
The RC circuit automatically controls the ESD protection trigger voltage without requiring additional control logic or active management. The capacitor naturally charges and discharges through the resistor, providing self-regulating trigger voltage control that eliminates the need for complex active shut-off management
3Adaptability or versatility
If active shut-off circuitry is used, then ESD protection can be dynamically controlled, but area occupation on the die increases
Solution Approach 1:
The patent removes the active shut-off transistor and associated control circuitry from the die, retaining only the essential RC components. This extraction eliminates the need for large isolation regions and reduces the overall area occupied by the ESD protection control mechanism while preserving dynamic control through the passive RC time constant
Solution Approach 2:
The RC circuit serves multiple functions: it filters normal signal variations, controls trigger voltage, and provides dynamic adaptation to ESD events without requiring separate active control circuits. This multi-functionality reduces the total component count and die area compared to dedicated active shut-off circuitry
4Ease of operation
If active shut-off circuitry is used, then ESD protection can be turned off during normal operation, but design and testing complexity increases
Solution Approach 1:
The patent replaces the complex active control system with a simple passive RC circuit whose behavior is determined by basic electrical time constants. This substitution dramatically simplifies both design (no active control logic needed) and testing (predictable RC charging/discharging behavior) while maintaining operational control capability
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 effectively reduces rate sensitivity, increases immunity to false triggering, and enhances reliability by eliminating the need for active shut-off circuits, conserving space and simplifying design and testing while maintaining effective ESD protection.
Implementation Method 1
a capacitor connected between the control node and an internal node... the capacitor and blocking circuit are selected so that a time constant representing the product of the capacitance and a diode leakage resistance is greater than the period of the time-varying signal
Implementation Method 2
A blocking circuit such as a diode is connected between the protected node and the internal node to allow charging current to flow from the protected node to charge the capacitor and to provide a high impedance to the internal node to prevent or mitigate flow of leakage current
Implementation Method 3
The resistor in certain examples, the resistor allows current to flow from the capacitor to the reference node to increase the amplitude of the control voltage signal to turn the ESD protection element on in response to an ESD event
Data Source
AI summary
Disclosed examples include an ESD protection circuit, including a transistor operative according to a control voltage signal at a control node to selectively conduct current from a protected node to a reference node during an ESD event, as well as a resistor connected between the control node and the reference node, a capacitor connected between the control node and an internal node, and a diode with an anode connected to the protected node and a cathode connected to the internal node to allow charging current to flow from the protected node to charge the capacitor and to provide a high impedance to the internal node to prevent or mitigate flow of leakage current from the internal node to the protected node to raise a trigger voltage of the protection circuit during normal operation.