Compact MOS ESD Protection Circuit With Shared Substrate Resistor
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Solution Overview
Problem
Existing ESD protection devices for integrated circuits can be triggered during normal operation due to uncontrolled environmental conditions, leading to potential damage and errors, and they often occupy significant surface area, especially when distributed across multiple signal terminals.
Innovation Solution
The integration of MOS transistors with a common resistor coupling the substrate and gate to the reference terminal, allowing for direct or indirect gate-reference coupling, prevents premature triggering and reduces the footprint by enabling a compact, hybrid operation-compatible ESD protection system across multiple terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESD protection devices are distributed across multiple signal terminals, then protection coverage is improved, but surface area occupied increases
Solution Approach 1:
The patent combines multiple ESD protection devices into a single integrated structure where multiple MOS transistors share common components including a common substrate resistor, common source region, and common drain region. This merging approach maintains comprehensive protection across multiple signal terminals while significantly reducing the total surface area required compared to distributed separate devices.
2Reliability
If hybrid operation transistors are used for ESD protection, then resistance to ionizing radiation is improved, but device complexity increases
Solution Approach 1:
The hybrid operation transistor serves multiple functions within a single device structure: it provides ESD protection, exhibits resistance to ionizing radiation, and maintains low power consumption during normal operation. The same transistor structure that enables radiation resistance through its bipolar component also provides the ESD protection capability, eliminating the need for separate dedicated ESD devices and reducing overall system 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
This configuration effectively absorbs electrostatic discharge currents between any pair of terminals, preventing damage and errors while maintaining a reduced footprint, even during operation, by ensuring the gate of the MOS transistors is not prematurely polarized and allowing for efficient triggering of the protection devices.
Implementation Method 1
An electrostatic discharge generally results in a current peak varying in size (amplitude, magnitude) and brevity (time) between two terminals of an electronic module of the integrated circuit
Implementation Method 2
the breakdown of the drain-substrate or source-substrate junction of the first MOS transistor TR1
Implementation Method 3
Hybrid operation transistors are MOS transistors comprising a parasitic bipolar transistor the operation of which involves an operation of this bipolar transistor and an operation of the MOS transistor in a sub-threshold mode
Data Source
AI summary
An integrated circuit includes a power supply terminal, a reference terminal, and a signal terminal. A first protection device is coupled between the signal terminal and the power supply terminal, the first protection device including a first MOS transistor. A second protection device is coupled between the signal terminal and the reference terminal, the second protection device including a second MOS transistor. Gates of the MOS transistors are directly or indirectly coupled to the reference terminal. Substrates of the MOS transistors are coupled to the reference terminal via a common resistor.