Bi-Directional MOS Switch Body Clamping for ESD and Hot-Plug Events
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Solution Overview
Problem
Existing bi-directional MOS-based switches face challenges in protecting against electrostatic discharge (ESD) and hot-plug events, which can cause damage and require effective protection mechanisms.
Innovation Solution
A bi-directional MOS-based switch arrangement incorporating first and second clamp circuits with transistors and diodes to provide ESD protection, clamping terminal-to-terminal voltages, and ensuring the MOS switch is self-protected by shorting its body to the source terminal during transient events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bi-directional MOS-based switch is used, then the switch can operate bidirectionally with low on-resistance, but the switch becomes vulnerable to electrostatic discharge and hot-plug events
Solution Approach 1:
The patent introduces intermediary protection circuits between the MOS switch and the external environment. These circuits include clamp circuits with Zener diodes and transient voltage suppression networks that act as mediators to capture and dissipate voltage transients before they reach the MOS switch, thereby protecting the switch from ESD and hot-plug events while maintaining its bidirectional operation
Solution Approach 2:
The protection circuits are designed to activate before voltage transients can damage the MOS switch. Zener diodes are selected with breakdown voltages slightly above the normal operating voltage, creating a cushioning effect that absorbs excess voltage energy through controlled breakdown, preventing direct exposure of the MOS switch to harmful voltage spikes
2Reliability
If protection circuits are added to the MOS switch, then electrostatic discharge protection is provided, but the device complexity increases
Solution Approach 1:
The patent merges multiple protection functions into integrated circuit configurations. The clamp circuits are designed to simultaneously handle both ESD protection and hot-plug event protection, while also maintaining bidirectional switch operation. This consolidation reduces the number of separate components needed compared to implementing each function independently
Solution Approach 2:
The protection circuits are designed with multi-functionality to address multiple threats with a single circuit architecture. The same clamp circuit structure provides protection against both electrostatic discharge and hot-plug voltage transients, eliminating the need for separate protection circuits for each threat type and thereby reducing overall device 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 switch arrangement effectively limits drain-source and source-drain voltages during ESD and hot-plug events, preventing damage and maintaining optimal performance by rapidly conducting ESD currents and clamping voltages to safe levels.
Implementation Method 1
a first diode of Zener diode type having an anode terminal coupled to the body of the MOS switch and a cathode terminal coupled to the source terminal
Implementation Method 2
a bi-directional metal-oxide-semiconductor, MOS, switch having a drain terminal, a source terminal, a gate terminal and a body
Data Source
Figure 1~2
Figure 3~4
AI summary
A switch arrangement comprising: a bi-directional metal-oxide-semiconductor, MOS, switch having a drain, source and gate and a body; a first circuit coupled between the drain, the gate and the source for providing electrostatic discharge protection; a first transistor having a source coupled to the body of the MOS switch, a drain coupled to the source of the MOS switch and a gate coupled to the gate of the MOS switch; and a second circuit for providing electrostatic discharge protection comprising a first diode of Zener diode type having an anode coupled to the body of the MOS switch and a cathode coupled to the source, and a second transistor having a source coupled to the body of the MOS switch, a drain coupled to the source of the MOS switch and a gate coupled to the anode of the first diode.