Bi-Directional TVS With Segmented Base Doping
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Solution Overview
Problem
Existing high surge transient voltage suppressors (TVS) face a trade-off between low leakage current and clamping voltage, as increasing base doping to reduce leakage current compromises clamping voltage, and require separate protection for power and data pins with different capacitance needs.
Innovation Solution
A bi-directional TVS is constructed using an NPN bipolar transistor with individually optimized collector-base and emitter-base junctions in avalanche mode breakdown, featuring a lightly doped base region bordered by more heavily doped regions to achieve low leakage current and robust clamping voltage, allowing for tunable breakdown voltage to match the protected device's operating voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If base doping level is increased to reduce leakage current, then leakage current is reduced, but clamping voltage is compromised
Solution Approach 1:
The base region is divided into two distinct doping zones: a lightly-doped first base region (112) for low leakage current and a heavily-doped second base region (114) for robust clamping voltage. This local differentiation allows each region to optimize its function independently, resolving the contradiction between low leakage and high clamping voltage.
Solution Approach 2:
The base doping structure is segmented into multiple regions with different doping concentrations. The first base region has a lower doping concentration than the second base region, creating distinct functional zones within the base that simultaneously achieve low leakage current and high clamping voltage characteristics.
2Reliability
If protection device capacitance is increased for power supply pins, then surge protection is improved, but data speed is reduced
Solution Approach 1:
The invention enables independent optimization of capacitance parameters for different pin types through the bipolar transistor structure. Power supply pins can utilize the full capacitance of the TVS device for maximum surge protection, while data pins experience minimal capacitance impact, allowing both high surge protection and high data speed requirements to be satisfied simultaneously.
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 design provides high surge protection with low leakage current and improved clamping voltage characteristics, meeting the needs of both power and data pins while adhering to international surge protection standards.
Implementation Method 1
individually optimized collector-base and emitter-base junctions both with avalanche mode breakdown
Data Source
AI summary
A transient voltage suppressor (TVS) is constructed as an NPN bipolar transistor including individually optimized collector-base and emitter-base junctions both with avalanche mode breakdown. The TVS device is constructed using a base that includes a lightly doped base region bordered by a pair of more heavily doped base regions. The two more heavily doped base regions are used to form the collector-base junction and the emitter-base junction both as avalanche breakdown junctions. The lightly doped base region between the collector-base and emitter-base doping regions ensures low leakage current in the TVS device. In this manner, the TVS bipolar transistor of the present invention provides high surge protection with robust clamping while ensuring low leakage current.