Low Capacitance TVS Device With Segmented Voltage Clamp
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Solution Overview
Problem
Conventional low capacitance high holding voltage transient voltage suppressing (TVS) devices face challenges in independently scaling reverse breakdown voltage and intrinsic snap-back voltage, as these parameters are interdependent, making it difficult to customize the device's protection capabilities effectively.
Innovation Solution
The design incorporates a voltage clamp component with adjustable doping concentrations, allowing for independent scaling of the trigger voltage and holding voltage, using a semiconductor material like silicon with specific conductivity types, and employing an intrinsic diode of the SCR instead of a low side diode to reduce components and capacitance, enabling higher breakdown voltage of the SCR while maintaining desired holding voltage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional low capacitance high holding voltage TVS devices are realized by connecting a low capacitance forward diode in series with a high reverse blocking large area/cap diode clamp, then the holding voltage is determined by the snap-back voltage of the transistor and the blocking capability of breakdown voltage, but it is difficult to independently scale the reverse breakdown voltage and the intrinsic snap-back voltage as they are interdependent
Solution Approach 1:
The invention divides the TVS device into two functionally independent segments: a first TVS diode structure dedicated to reverse breakdown voltage control and a second TVS diode structure dedicated to snap-back voltage control. This segmentation allows each segment to be optimized independently for its specific function, eliminating the interdependence problem in conventional single-structure devices. The first diode can be scaled for reverse breakdown protection while the second diode can be separately scaled for snap-back characteristics, providing independent scaling capability.
2Reliability
If a high reverse blocking large area/cap diode clamp is used to achieve high holding voltage, then the holding voltage increases, but the capacitance also increases
Solution Approach 1:
The invention segments the holding voltage function from the capacitance-contributing elements. The high holding voltage is achieved through the first TVS diode structure with optimized reverse breakdown characteristics, while the second TVS diode structure provides low-capacitance snap-back protection. This segmentation allows the device to maintain high holding voltage without requiring a large area/capacitance clamp diode, thus reducing overall capacitance.
Solution Approach 2:
The invention changes the structural parameters of the TVS device by implementing two distinct diode structures with different geometric and material parameters. The first diode is designed with parameters optimized for reverse breakdown voltage (affecting holding voltage), while the second diode is designed with parameters optimized for low capacitance and snap-back characteristics. This parameter differentiation allows simultaneous achievement of high holding voltage and low capacitance.
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 allows for the creation of TVS devices with high holding voltage and low capacitance, enabling customizable protection against transient voltage spikes without affecting the breakdown voltage, thereby enhancing the device's operational flexibility and effectiveness.
Implementation Method 1
The snap back voltage is the voltage at which the avalanche breakdown or impact ionization occurring within the transistor (or rectifier) provides sufficient current to turn the transistor to the on state
Implementation Method 2
The snap back voltage is the voltage at which the avalanche breakdown or impact ionization occurring within the transistor (or rectifier) provides sufficient current to turn the transistor to the on state
Data Source
AI summary
A transient voltage suppressing (TVS) device including a first silicon-controlled rectifier and a voltage clamp having a first terminal and a second terminal. The first terminal is connected to a cathode of the first silicon-controlled rectifier.