TVS Diode Series Junctions for Low Parasitic Capacitance
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Solution Overview
Problem
Conventional transient voltage suppressors (TVS) face challenges in reducing parasitic capacitance while maintaining effective electrostatic discharge (ESD) and surge protection capabilities, as increasing the number of diodes in series to reduce capacitance leads to higher on-resistance and compromised protection capabilities.
Innovation Solution
The TVS diode device incorporates a substrate with separated wells and electrodes, forming a current path through multiple PN junctions with varying gaps and doping concentrations to reduce parasitic capacitance while maintaining ESD and surge protection, allowing for selection of diode type based on gap and doping parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the area of the diode is increased to bear great energy, then the ESD and surge protection capability is improved, but the parasitic capacitance increases and the operation rate slows down
Solution Approach 1:
The patent divides a single large-area diode into multiple smaller diodes connected in series. Each small diode has low capacitance due to its small area, but when connected in series, they collectively provide the necessary current handling capability for ESD and surge protection. The segmentation allows the TVS device to achieve both low capacitance and high power handling capability.
2Speed
If the number of diodes coupled in series is increased to reduce capacitance, then the parasitic capacitance is reduced, but the on-resistance becomes larger and the ESD and surge protection capability deteriorates
Solution Approach 1:
The patent optimizes the local properties of each diode in the series connection. By carefully designing the area, doping concentration, and structure of each individual diode, the patent achieves low capacitance while maintaining low on-resistance. The local quality of each diode is tailored to contribute to both low capacitance and low overall resistance of the series string.
3Speed
If diodes with small area are used to reduce capacitance, then the parasitic capacitance is reduced, but the ESD and surge protection capability is limited
Solution Approach 1:
The patent merges multiple small diodes in series to create a composite structure that exhibits both low capacitance and high power handling capability. The series connection of multiple low-capacitance diodes creates an equivalent capacitance that is lower than any individual diode, while the cumulative current handling capability of all diodes in series provides the necessary power handling for ESD and surge 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 approach effectively reduces parasitic capacitance while maintaining ESD and surge protection capabilities, allowing for flexible diode configuration to suit different applications by adjusting gap and doping concentrations.
Implementation Method 1
the parasitic capacitance and slow operation rate
Implementation Method 2
PN junctions having large area are necessary in the TVS
Data Source
AI summary
A diode device of a transient voltage suppressor (TVS) is disclosed. The diode device includes a substrate, a first well, a second well, a first electrode and a second electrode. The substrate has a first surface. The first well is formed in the substrate and near the first surface. The second well is formed in the substrate and near the first surface. There is a gap between the first well and the second well. The first electrode is electrically connected with the first well. The second electrode is electrically connected with the second well. A current path is formed from the first electrode, the first well, the substrate, the second well to the second electrode. The current path passes through a plurality of PN junctions to form an equivalent circuit having a plurality of equivalent capacitances coupled in series.