ESD Clamp Circuit With Staged NMOS Discharge Paths
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Solution Overview
Problem
Integrated circuits are vulnerable to damage from electrostatic discharge (ESD) due to high voltage spikes during ESD events, as existing ESD protection circuits often have trigger voltages close to the breakdown voltage, leading to delayed discharge and potential device failure.
Innovation Solution
The proposed ESD circuit design incorporates n-type transistors and a power clamp module with a reduced trigger voltage, featuring multiple discharge paths and an embedded NMOS transistor to quickly divert electrostatic charges, thereby reducing the overall trigger voltage and enhancing robustness against ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ESD protection circuits are used, then ESD protection is provided, but the trigger voltage is close to the breakdown voltage causing delayed discharge and potential device failure
Solution Approach 1:
The ESD protection circuit is segmented 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 each transistor to operate at optimized trigger voltages, with the second transistor providing lower trigger voltage discharge path that activates before the first transistor, enabling timely ESD protection while maintaining reliability.
Solution Approach 2:
The invention changes the trigger voltage parameter by introducing a second transistor with a lower breakdown voltage than the first transistor. The second transistor's breakdown voltage is specifically designed to be lower than the first transistor's breakdown voltage, creating a staged discharge mechanism where the lower voltage path activates first, reducing the overall trigger voltage and preventing delayed discharge.
2Loss of time
If trigger voltage is reduced for timely discharge, then ESD protection response time is improved, but device robustness against high voltage spikes may be compromised
Solution Approach 1:
The circuit dynamically switches between different discharge paths based on the voltage level. At normal operating voltages, the second transistor provides a low-impedance discharge path for rapid response. When voltage exceeds the first transistor's breakdown voltage, the first transistor activates to handle higher voltage spikes. This dynamic adaptation allows the circuit to provide both fast response time and robust protection against high voltage events.
Solution Approach 2:
The second transistor is designed to activate first at a lower voltage threshold, creating a preliminary discharge path that kicks in before the first transistor. This preliminary action ensures timely discharge of ESD events at lower voltage levels, while the first transistor stands ready to provide additional protection if the voltage spike exceeds the second transistor's breakdown voltage.
3Reliability
If multiple discharge paths are added to reduce trigger voltage, then ESD protection capability is enhanced, but circuit complexity increases
Solution Approach 1:
The invention merges the ESD protection function with existing circuit elements by integrating the first and second transistors into the power clamp module. The transistors share common connections to power rails and ground, and their combined operation provides enhanced ESD protection without requiring completely separate protection circuits. This merging approach enhances protection capability while minimizing additional complexity.
Solution Approach 2:
The first and second transistors serve multiple functions: they provide ESD protection through their breakdown characteristics, act as voltage clamps during normal operation, and create staged discharge paths for different voltage levels. This multi-functionality allows the same circuit elements to provide both ESD protection and voltage regulation, enhancing protection capability without proportionally increasing circuit complexity.
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 for ESD events, ensuring timely discharge of electrostatic charges and protecting sensitive components from damage, while maintaining a compact layout without the need for large RC components.
Implementation Method 1
In response to the first terminal reaching a trigger voltage, the first transistor may be turned on
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.