Dynamically Terminated Diode String ESD Protection Circuit
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Solution Overview
Problem
Conventional electrostatic discharge (ESD) protection circuits using diode strings often include unnecessary components and are not optimized to dynamically adjust their length based on the ESD event, leading to inefficient current dissipation.
Innovation Solution
A dynamically terminating diode string circuit with metal oxide semiconductor field effect transistors (MOSFETs) that can be activated during ESD events to divert current away from the diode string, reducing voltage levels and dynamically altering the effective length of the diode string for each event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diode string is designed to dissipate worst-case ESD events, then ESD protection capability is improved, but the circuit includes multiple components that remain unused in normal operation, increasing device complexity
Solution Approach 1:
The patent implements dynamic termination of the diode string using switches (transistors) that are activated during ESD events to disconnect portions of the diode string from the power supply. This allows the circuit to adapt its configuration based on ESD event severity, using only the necessary number of diode stages rather than permanently configuring for worst-case scenarios. The switches enable the circuit to transition from a static, over-provisioned design to a dynamic, demand-responsive architecture.
2Reliability
If a diode string is designed to handle worst-case ESD events, then ESD protection capability is improved, but unnecessary components are included that are only used occasionally, reducing ease of operation
Solution Approach 1:
The circuit dynamically adjusts the active portion of the diode string during ESD events through switch activation. During normal operation, the circuit operates efficiently with minimal components engaged. During ESD events, additional diode stages are activated only as needed, allowing the circuit to optimize its operational efficiency while maintaining protection capability.
3Productivity
If MOSFETs are added to dynamically terminate the diode string, then ESD current dissipation efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces MOSFETs as intermediary switching devices that mediate between the diode string and the power supply. These MOSFETs act as controlled connection points that can rapidly activate or disconnect diode stages during ESD events. The MOSFETs simplify the control logic by providing direct electrical switching capability, eliminating the need for complex control circuits while improving response time and dissipation efficiency.
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 dissipates ESD currents by selectively engaging MOSFETs to dissipate current to ground, reducing the voltage across multiple stages of the diode string and optimizing the number of stages used for each ESD event, thereby improving efficiency and reducing unnecessary component usage.
Implementation Method 1
Each of the plurality of switches is controllable to selectively couple the anode to the power supply terminal in response to an ESD event. The plurality of switches configured to dissipate an ESD current associated with the ESD event and dynamically terminate the unterminated diode string
Data Source
AI summary
An integrated circuit includes a plurality of terminals, an unterminated diode string formed from a plurality of P-N junction devices arranged in series and coupled to the plurality of terminals, and a plurality of switches. Each of the plurality of switches includes a first terminal coupled to an anode of one of the plurality of P-N junction devices and a second terminal coupled to a power supply terminal, and is controllable to selectively couple the anode to the power supply terminal in response to an ESD event. The plurality of switches configured to dissipate an ESD current associated with the ESD event and dynamically terminate the unterminated diode string at a node where the ESD current falls below a turn-on threshold of a next P-N junction device in the unterminated diode string.