ESD Clamp Circuit With Multiple Discharge Paths and Low Trigger Voltage
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Solution Overview
Problem
Electrostatic discharge (ESD) protection circuits in integrated circuits face challenges in effectively discharging electrostatic charges before they reach damaging voltages, leading to potential device failure due to high trigger voltages that are close to breakdown voltages, especially under rapid charge accumulation conditions.
Innovation Solution
The proposed ESD circuit design incorporates n-type transistors and a power clamp module with a reduced trigger voltage, utilizing multiple discharge paths and an embedded NMOS transistor to ensure timely discharge of electrostatic charges, thereby reducing the overall trigger voltage and enhancing robustness against ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ESD protection circuits are used, then the circuit can provide basic ESD protection, but the trigger voltage is too high and close to the breakdown voltage, causing delayed discharge response under rapid charge accumulation
Solution Approach 1:
The ESD protection circuit is divided into multiple parallel discharge paths: a first discharge path through a first transistor and a second discharge path through a second transistor. This segmentation allows different transistors to be triggered at different voltage thresholds, enabling staged discharge response and improving both reliability and response speed.
Solution Approach 2:
The circuit dynamically activates different discharge paths based on the instantaneous voltage level. The first transistor triggers at a lower voltage threshold while the second transistor triggers at a higher voltage threshold, creating a dynamic, adaptive discharge response that optimizes both speed and reliability across different ESD event intensities.
2Speed
If the trigger voltage is reduced to enable timely discharge, then the response speed improves, but the circuit becomes more sensitive and may trigger falsely under normal operating conditions
Solution Approach 1:
The circuit employs dynamic voltage thresholding with multiple transistors having different trigger voltages. Normal operating voltages remain below the lowest trigger threshold, preventing false triggers, while ESD events rapidly exceeding these thresholds trigger appropriate discharge paths. This dynamic response ensures fast protection without excessive sensitivity.
Solution Approach 2:
The circuit provides feedback through the parallel transistor configuration where each transistor monitors the voltage at its gate and activates discharge only when its specific threshold is exceeded. This feedback mechanism ensures that discharge occurs only when genuinely needed, filtering out normal operating variations while responding to actual ESD threats.
3Reliability
If multiple discharge paths are added to improve discharge capability, then the ESD protection effectiveness increases, but the device complexity increases
Solution Approach 1:
The ESD protection is segmented into multiple parallel transistor-based discharge paths, each independently controllable. This segmentation improves discharge effectiveness by providing multiple routes for charge dissipation while maintaining a relatively simple overall circuit structure that can be integrated into existing CMOS processes.
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 the trigger voltage, ensuring timely discharge of electrostatic charges and protecting sensitive components from damage, even under rapid charge accumulation, by utilizing multiple discharge paths and an embedded NMOS transistor, thus enhancing the robustness of the ESD circuit.
Implementation Method 1
Electrostatic discharge (ESD) protection may be called upon to discharge the accumulated electrostatic charges
Data Source
AI summary
The present disclosure provides electrostatic discharge circuits and structures and methods for operating the electrostatic discharge circuits and structures. A circuit includes a first transistor and a second transistor. The first transistor includes a drain, a source, a gate, and a bulk. The drain of the first transistor is connected to a first terminal. The source of the first transistor is connected to receive a first voltage. The gate and the bulk of the first transistor is connected to receive a second voltage. The second transistor includes a drain, a source, a gate, and a bulk. The source, the gate, and the bulk of the second transistor is connected to receive the second voltage. The drain of the second transistor is connected to the first terminal. In response to the terminal reaching a trigger voltage, the first transistor is configured to be turned on.