ESD Circuit with Dynamic Switching Resistor
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Solution Overview
Problem
As semiconductor integrated circuits are scaled down, they face increased vulnerability to electrostatic discharge (ESD), which can damage components like MOS transistors due to high electrostatic voltages, necessitating effective protection mechanisms.
Innovation Solution
The implementation of an electrostatic discharge circuit with a driver, switch protection resistor, and ESD detector that adjusts electrical resistance between a pad and driver based on a switch control signal, forming either a current path through or bypassing a protection resistor depending on ESD events, to manage and protect against electrostatic discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection resistor is always connected between the pad and driver, then ESD protection is provided, but the electrical resistance increases during normal operation affecting signal integrity
Solution Approach 1:
The patent applies a switching mechanism that dynamically changes the electrical resistance between the pad and driver based on operating conditions. During normal operation, the switch connects the pad directly to the driver (low resistance). During ESD events, the switch connects the protection resistor (high resistance). This dynamic adjustment resolves the contradiction by providing both signal integrity during normal operation and ESD protection during events.
Solution Approach 2:
The switching mechanism acts as an intermediary between the pad and driver, selectively inserting the protection resistor based on ESD detection. The switch control signal generated by the ESD detector controls this intermediary element to provide protection only when needed, maintaining signal integrity during normal operation while enabling ESD protection when required.
2Object-affected harmful factors
If the electrical resistance between pad and driver is increased for ESD protection, then current flow during ESD is limited, but normal operation performance deteriorates
Solution Approach 1:
The electrical resistance is made dynamic rather than static. The switch control signal causes the resistance to be low (direct connection) during normal operation for optimal performance, and high (through protection resistor) during ESD events for current limiting. This dynamic resistance adjustment resolves the contradiction between ESD protection and normal operation performance.
3Reliability
If a switching mechanism is added to adjust resistance dynamically, then both normal operation and ESD protection are optimized, but device complexity increases
Solution Approach 1:
The switching mechanism and protection resistor are integrated into the existing pad driver structure, allowing these components to serve dual functions: maintaining signal integrity during normal operation and providing ESD protection during events. The ESD detector also serves multiple purposes by monitoring voltage levels and generating control signals. This multi-functionality approach minimizes additional complexity while achieving optimized ESD protection.
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 protects internal circuits from ESD by limiting current flow during events, maintaining normal operation resistance levels and enhancing ESD protection efficiency.
Implementation Method 1
an ESD detector configured to detect a voltage level of the first or second power voltage and generate the switch control signal
Implementation Method 2
a switch protection resistor configured to change an electrical resistance between the pad and the second driver in response to a switch control signal
Implementation Method 3
a first driver configured to pull up a voltage level of a pad to a first power voltage in response to a driving signal, a second driver configured to pull down the voltage level of the pad to a second power voltage
Data Source
AI summary
A semiconductor device includes a first driver configured to pull up a voltage level of a pad to a first power voltage in response to a driving signal, a second driver configured to pull down the voltage level of the pad to a second power voltage in response to the driving signal, a switch protection resistor configured to change an electrical resistance between the pad and the second driver in response to a switch control signal, and an ESD detector configured to detect a voltage level of the first or second power voltage and generate the switch control signal.