Drain-Ballasted Transistor Pull-Down Circuit ESD Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ESD protection designs for integrated circuit devices often result in victim devices being damaged due to high snapback turn-on voltage before the ESD primary circuit is activated, as the trigger voltage of the ESD primary circuit is greater than the breakdown voltage of the pull-down circuit transistors, leading to premature destruction during electrostatic discharge events.
Innovation Solution
The integration of a drain-ballasted transistor with a wider active region in the pull-down circuit, which increases its breakdown voltage to be about 2 to 3 times greater than traditional approaches, allowing it to withstand ESD currents until the ESD primary circuit is activated, and the use of multiple transistors in series and parallel configurations to enhance ESD performance and layout efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional ESD primary circuit is used, then ESD protection function is provided, but victim devices are damaged due to high snapback turn-on voltage before ESD primary circuit is activated
Solution Approach 1:
A drain-ballasted transistor is introduced as an intermediary component between the pad and the ESD primary circuit. This transistor acts as a mediator that limits the snapback turn-on voltage to a safe level, preventing damage to victim devices while still enabling the ESD primary circuit to activate and provide protection. The drain-ballasted transistor effectively decouples the harmful high voltage from the victim devices while maintaining the protective function.
Solution Approach 2:
The invention changes the voltage parameter characteristics by using a drain-ballasted transistor configuration that limits the snapback turn-on voltage to be lower than the breakdown voltage of victim devices. This parameter modification ensures that the voltage waveform during ESD events has a controlled peak that protects sensitive circuits while still allowing the ESD primary circuit to turn on effectively.
2Strength
If drain-ballasted transistor with wider active region is used, then breakdown voltage is increased to withstand ESD currents, but device area increases
Solution Approach 1:
The pull-down circuit is segmented into multiple transistors connected in series, where each transistor has a moderate-sized active region. This segmentation allows the total breakdown voltage to be distributed across multiple components, achieving the required voltage withstand capability without requiring a single large transistor that would consume excessive layout area.
Solution Approach 2:
The invention uses asymmetric configuration of transistor active regions, where the drain-ballasted transistor has a wider active region than standard transistors to achieve higher breakdown voltage, while other transistors in the series chain have smaller active regions. This asymmetric design optimizes the overall breakdown voltage while minimizing total layout area by concentrating the width enhancement only where most needed.
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 prevents damage to integrated circuit devices by ensuring the pull-down circuit can handle ESD currents without being destroyed, and improves ESD performance and layout efficiency, enabling the ESD primary circuit to activate and discharge currents effectively, thus enhancing the overall ESD protection.
Implementation Method 1
a drain-ballasted transistor with a wider active region in the pull-down circuit, which increases its breakdown voltage to be about 2 to 3 times greater than traditional approaches, allowing it to withstand ESD currents until the ESD primary circuit is activated
Data Source
AI summary
An integrated circuit includes a pull-up circuit, an electrostatic discharge (ESD) primary circuit, and a pull-down circuit. The pull-up circuit is coupled between a pad and a first voltage terminal. The ESD primary circuit includes a first terminal which is coupled to the pad and the pull-up circuit, and a second terminal coupled to a second voltage terminal different from the first voltage terminal. The pull-down circuit has a first terminal which is coupled to the pad, the ESD primary circuit and the pull-up circuit, and a second terminal coupled to the second voltage terminal. The pull-down circuit includes at least one first transistor of a first conductivity type having a first terminal coupled to the first terminal of the pull-down circuit. A breakdown voltage of the at least one first transistor is greater than a trigger voltage of the ESD primary circuit.