ESD Avoiding Circuit with Segmented Transistors and RC Filter

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Solution Overview

Problem

Conventional ESD protection circuits often allow ESD current to flow into core circuits due to high trigger-on voltages, potentially damaging internal components, and may experience leakage currents during regular operation modes, especially when boosting programming voltages.

Innovation Solution

An ESD avoiding circuit comprising a first ESD protection unit, an ESD detection unit, a switch unit, and an RC filter unit is designed to detect ESD occurrences and control the flow of ESD current, while ensuring operation voltage is provided to core circuits during regular operation, thereby preventing damage and leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional ESD protection circuit with high trigger-on voltage is used, then the ESD current can be blocked, but the ESD current may still flow into the core circuit before the protection transistor turns on, causing damage

Engineering Contradiction:

ImproveESD protection capabilityVSAvoidESD current damage to core circuit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The ESD protection function is divided into two independent parts: a first ESD protection unit (transistor N0) with high trigger-on voltage for general protection, and a second ESD protection unit (transistor N1) with low trigger-on voltage for immediate ESD current diversion. This segmentation allows each unit to specialize in different aspects of ESD protection, resolving the contradiction between blocking capability and response timing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Transistor N1 acts as an intermediary between the ESD event and the core circuit. When ESD occurs, N1 quickly turns on with its low trigger-on voltage to divert the ESD current away from the core circuit, while N0 maintains its high trigger-on voltage for normal operation protection. This intermediary mechanism prevents direct damage to the core circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the trigger-on voltage of the ESD protection transistor is lowered to prevent ESD current damage, then ESD protection improves, but leakage current occurs during regular operation mode

Engineering Contradiction:

ImproveESD current damage preventionVSAvoidleakage current

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The protection function is segmented into two transistors with different trigger-on voltages: N0 with high trigger-on voltage that remains off during normal operation (no leakage), and N1 with low trigger-on voltage that activates only during ESD events. This segmentation allows the system to achieve both ESD protection and low leakage current during regular operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the ESD protection system have different electrical characteristics tailored to their specific functions. N0 has high trigger-on voltage suitable for normal operation protection, while N1 has low trigger-on voltage optimized for rapid ESD response. This local quality differentiation resolves the contradiction between protection effectiveness and leakage prevention.

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single ESD protection transistor is used, then the circuit structure is simple, but it cannot simultaneously provide ESD protection and prevent leakage current

Engineering Contradiction:

Improvecircuit structureVSAvoidESD protection effectiveness

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The ESD protection function is segmented into two transistors working in parallel, each with optimized characteristics for their specific role. This segmentation increases reliability by ensuring both immediate ESD response and normal operation protection, while maintaining relatively simple circuit structure through the parallel configuration.

Inventive Principle:

Principle #1Segmentation

4Loss of energy

If an RC circuit is used to control the ESD protection transistor during regular operation, then leakage current is prevented, but the RC circuit may delay the signal and cause misoperation

Engineering Contradiction:

Improveleakage current preventionVSAvoidsignal response speed

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The control mechanism is segmented into two paths: one through the RC circuit for gradual voltage adjustment during normal operation (preventing leakage), and another direct path for rapid ESD response. This segmentation allows the system to achieve both leakage prevention and fast signal response by routing ESD signals through the direct path bypassing the RC delay.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7660087B2Electrostatic discharge avoiding circuit

Publication Date: 2010.02.09 EMEMORY TECH INC

AI summary

An ESD avoiding circuit includes a first ESD protection unit, an ESD detection unit, a switch unit, and an RC filter unit. The first ESD protection unit transmits an ESD current between a first conducting path and a second conducting path. The ESD detection unit is coupled to the first conducting path. The ESD detection unit includes an input terminal, and an output terminal coupled to the first ESD protection unit for detecting an ESD and controlling the first ESD protection unit to conduct the ESD current according to a detection result. The switch unit is coupled between the first conducting path and a core circuit and conducts the first conducting path to the core circuit according to signals of the input terminal and the output terminal of the ESD detection unit. The RC filter unit couples a first voltage to the input terminal of the ESD detection unit.