ESD Protection Circuit with Dual Clamping Paths
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Solution Overview
Problem
Conventional ESD protection circuits for large-signal circuits suffer from reduced effectiveness due to increased turn-on resistance and time in diode strings, which can lead to ESD current flowing into the protected circuit, limiting the voltage swing and causing waveform clipping.
Innovation Solution
The proposed ESD protection circuit employs a diode string with multiple diodes connected in series between the output terminal and operating voltages, along with two clamping circuits: one between the output terminal and the first operating voltage, and another between a connecting node of the diodes and the second operating voltage, to create a shorter conduction path for ESD current dissipation during ESD events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a diode string with multiple diodes is used to protect against voltage swing clipping, then the voltage swing is maintained, but the turn-on resistance and turn-on time increase
Solution Approach 1:
The ESD protection function is segmented into two independent paths: a fast protection path using a single diode (Dp1) for immediate ESD current shunting, and a voltage swing control path using a multi-diode string (Dp1-Dp5) for maintaining output voltage swing. This segmentation allows each path to be optimized independently - the single diode path for speed and the multi-diode path for voltage control - resolving the contradiction between protection effectiveness and voltage swing maintenance.
2Stability of the object's composition
If the number of diodes in the diode string is increased to maintain voltage swing, then the voltage swing is preserved, but the conduction path length increases
Solution Approach 1:
The conduction paths are segmented into two distinct routes: a short direct protection path through diode Dp1 for ESD current, and a longer voltage control path through the multi-diode string (Dp1-Dp5) for normal operation. The segmentation allows the ESD protection function to use the shortest possible path while the voltage swing function uses the appropriate multi-diode path, eliminating the trade-off between path length and voltage control.
Solution Approach 2:
Diode Dp1 serves as an intermediary element that participates in both ESD protection and voltage swing control. During ESD events, it provides a fast shunt path. During normal operation, it works with Dp2-Dp5 to maintain the required voltage swing. This dual role of Dp1 as an intermediary resolves the contradiction by allowing the same component to serve both functions with different characteristics.
3Length of moving object
If a single diode is used in the ESD protection circuit, then the conduction path is short, but the output voltage is clipped
Solution Approach 1:
The ESD protection function and voltage swing control function are merged into a single integrated circuit structure where diodes Dp1-Dp5 serve dual purposes. The same diode string that maintains voltage swing also provides ESD protection, eliminating the need for separate components and allowing both functions to coexist without compromising either conduction path length or output voltage waveform integrity.
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 significantly enhances the effectiveness of ESD protection by reducing the conduction path length and ensuring swift dissipation of ESD current, thereby preventing damage to the large-signal circuit and maintaining a perfect symmetrical waveform.
Implementation Method 1
ESD protection circuit and method thereof for dissipating electrostatic discharge (ESD) swiftly
Implementation Method 2
the diode string to have an increased turn-on resistance Rd (or an increased conduction path length)
Data Source
AI summary
An electrostatic discharge (ESD) protection circuit and method thereof is provided. The ESD protection circuit includes two clamping circuits, an inductor, a diode and a diode string. In addition to a voltage swing of an output voltage able to get rid of the influence of the ESD protection circuit, the invention reduces an ESD conduction path length and dissipates an ESD current swiftly by installing at least two clamping circuits, which significantly increases the effectiveness of the protection for large-signal circuits.