Bi-directional BJT for AC Power Switching
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Solution Overview
Problem
Traditional semiconductor power switches face limitations in switching AC power, including lack of AC switching ability, high costs, complex processing, inherent voltage drop, and high on-resistance, which hinder efficient operation and implementation of features like short-circuit protection.
Innovation Solution
A bi-directional bipolar junction transistor (BJT) structure with a lightly doped base region and heavily doped collector/emitter regions, capable of switching high voltages with low voltage drop and simple drive requirements, allowing for efficient AC switching and integration with microcontrollers for smart-power systems without specialized cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional semiconductor power switches (BJT, MOSFET, IGBT) are used, then DC switching is achieved, but AC switching ability is lacking
Solution Approach 1:
The device is segmented into distinct functional regions: a drift region for voltage blocking, a first active region and second active region for bidirectional current conduction, and a third active region for carrier injection. This segmentation enables the device to independently perform AC switching functions while maintaining manageable structural complexity through specialized zone design.
Solution Approach 2:
The semiconductor device is designed with multi-functionality to handle both DC and AC switching operations. The combination of the drift region, multiple active regions, and selective gate control enables the single device to perform unidirectional blocking, bidirectional conduction, and AC switching without requiring additional specialized components.
2Reliability
If expensive semiconductor materials and complex processing steps are used, then high voltage switching capability is achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The device structure utilizes controlled doping parameter changes across different regions: a lightly doped drift region for high voltage blocking, heavily doped active regions for efficient current conduction, and specifically engineered doping profiles in the third active region. These parameter variations enable high voltage capability while using standard semiconductor materials and processes.
Solution Approach 2:
The patent employs standard, well-established semiconductor fabrication processes to create the complex multi-region structure. By copying and adapting proven manufacturing techniques from existing power device production, the invention achieves high voltage capability without requiring expensive or complex proprietary processing steps.
3Ease of manufacture
If standard BJT, MOSFET, or IGBT structures are used, then manufacturing is possible, but inherent voltage drop (0.8 to 2.5 volts) limits efficiency
Solution Approach 1:
The device implements local quality variations through differentiated region design: the drift region maintains low doping for voltage blocking, while the active regions have high doping for low-resistance conduction. The third active region specifically provides localized carrier injection to reduce on-state voltage drop in the drift region, achieving lower power loss while maintaining manufacturability through standard processes.
4Reliability
If high on-resistance is used in high voltage devices, then voltage blocking capability is improved, but current conduction efficiency deteriorates
Solution Approach 1:
The device transitions from a single-layer structure to a multi-dimensional layered architecture with the drift region, first active region, second active region, and third active region stacked in sequence. This dimensional organization allows the drift region to maintain high resistance for voltage blocking while the active regions provide low-resistance conduction paths, and the third region injects carriers to further reduce effective resistance during conduction mode.
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
Enables efficient mains voltage switching, short-circuit protection, and data logging in smart-appliance systems with reduced costs and complexity, while maintaining high reliability and efficiency.
Implementation Method 1
providing a volume of an acid solution in the container, wherein the acid solution serves as an insulator
Implementation Method 2
drilling, using one or more needles supplied with a voltage, one or more holes on the surface of the substrate to locally invert the N-type substrate to a P-type substrate, wherein the voltage applied on the surface of the substrate anodically etches the surface of the substrate to create the one or more holes by surface inversion
Data Source
AI summary
A bi-directional bipolar junction transistor (BJT) structure, comprising: a base region of a first conductivity type, wherein said base region constitutes a drift region of said structure; first and second collector/emitter (CE) regions, each of a second conductivity type adjacent opposite ends of said base region; wherein said base region is lightly doped relative to said collector/emitter regions; the structure further comprising: a base connection to said base region, wherein said base connection is within or adjacent to said first collector/emitter region.