Series-Connected Semiconductor Switches for High Breakdown Voltage
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Solution Overview
Problem
High-voltage semiconductor switches face challenges in achieving optimal breakdown voltage and on-resistance, leading to increased size and cost, as well as the need for multiple transistor designs to accommodate varying voltage requirements, with limitations in exceeding available breakdown voltages.
Innovation Solution
A high-voltage electrical switch is designed using a series connection of semiconductor switches isolated by trenches or junctions, with a radio frequency signal generator and galvanic isolators to control the switches, allowing for customizable breakdown voltage through combinations of standardized sub-elements and reducing the overall area and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single high-voltage transistor is designed to achieve higher breakdown voltage, then the breakdown voltage increases, but the transistor area increases significantly (5-5.7 times larger for doubling breakdown voltage)
Solution Approach 1:
The patent divides a single high-voltage transistor into multiple lower-voltage transistors connected in series. Each transistor operates at a lower breakdown voltage, allowing smaller individual areas. The series connection distributes the total voltage stress across multiple devices, achieving the required high breakdown voltage without the exponential area penalty of a single transistor.
Solution Approach 2:
The patent transitions from a single-device vertical scaling approach to a multi-device series configuration. By adding the dimension of multiple series-connected transistors, the system achieves high breakdown voltage through voltage distribution across series elements rather than relying on a single large-area device, effectively moving from area-based voltage scaling to series-stacking voltage scaling.
2Adaptability or versatility
If multiple transistor designs are developed for different voltage requirements (20V, 60V, 100V), then coverage of voltage ranges improves, but design complexity and qualification effort increase
Solution Approach 1:
The patent creates a universal low-voltage transistor design that can be used in series combinations to achieve various high-voltage requirements. Instead of developing separate optimized transistors for 20V, 60V, 100V, and other voltage levels, a single standardized transistor design serves multiple functions when stacked in series, eliminating the need for multiple design cycles and qualification processes.
Solution Approach 2:
The patent changes the approach from modifying transistor parameters (drift region length, doping profile, gate location) for each voltage level to maintaining fixed transistor parameters and changing the number of series-connected devices. This allows the same transistor design to be configured for different voltage requirements simply by adjusting the series count, rather than redesigning each transistor for specific voltage levels.
3Reliability
If a 60V transistor is used for a 30V application, then voltage headroom is provided, but the area is 5 times larger than a dedicated 30V transistor would yield
Solution Approach 1:
The patent segments the voltage requirement into multiple smaller voltage portions handled by series-connected transistors. For a 30V application, instead of using a single oversized 60V transistor, the system uses two 30V transistors in series, where each transistor operates at its optimal design point with appropriate area, providing the necessary voltage headroom without excessive area penalty.
4Strength
If breakdown voltages beyond available technology (150V, 200V) are required, then the application requirements are met, but the transistor area and cost become prohibitive
Solution Approach 1:
The patent segments high-voltage requirements (150V, 200V, etc.) into multiple lower-voltage stages using series-connected transistors. This allows the use of standardized, cost-effective low-voltage transistor designs that can be mass-produced, rather than requiring expensive custom high-voltage transistor designs for each voltage level. The series configuration achieves high breakdown voltage through composition of multiple affordable units.
Solution Approach 2:
The patent combines multiple identical or similar low-voltage transistor designs in series to create high-voltage switching capability. This merging approach allows leveraging existing mature, low-cost transistor processes and designs to achieve high-voltage functionality, avoiding the need for prohibitively expensive custom high-voltage device development and manufacturing.
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 provides greater flexibility in designing high-voltage switches, reduces IC size, and allows for a wider range of breakdown voltages without the need for multiple transistor designs, achieving a smaller area and lower on-resistance while accommodating varying voltage demands.
Implementation Method 1
a plurality of rectifiers wherein each rectifier is connected to a semiconductor switch control input of one of the semiconductor switches
Implementation Method 2
a plurality of galvanic isolators, wherein each galvanic isolator connects the radio frequency signal generator to one of the plurality of rectifiers
Data Source
AI summary
A high voltage electrical switch including: a plurality of series connected semiconductor switches; a plurality of rectifiers wherein each rectifier is connected to a semiconductor switch control input of one of the semiconductor switches; a radio frequency signal generator; and a plurality of galvanic isolators, wherein each galvanic isolator connects the radio frequency signal generator to one of the plurality of rectifiers, wherein the plurality of semiconductor switches are isolated from one another.