High-Voltage Switch Topology for Polarity-Independent Current Interruption
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Solution Overview
Problem
High Voltage switches used in ultrasound apparatuses face limitations in interrupting current independently of voltage polarity due to the creation of a junction between source and drain terminals, leading to suboptimal performance during fast voltage transitions.
Innovation Solution
A High Voltage switch configuration comprising two diodes in antiseries with a triggering circuit that stores charges in the diodes before applying the input signal, allowing for a conductive path to be formed independently of voltage polarity, using a DMOS transistor, a third diode, and a resistor to generate a triggering current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single MOS transistor is used as a High Voltage switch, then the device complexity is reduced, but the ability to interrupt current independently of voltage polarity is lost due to the creation of a junction between source and drain terminals
Solution Approach 1:
The single MOS transistor is segmented into two separate MOS transistors connected in series. This segmentation allows each transistor to handle one polarity independently, enabling current interruption for both positive and negative voltage polarities without creating a blocking junction between source and drain terminals.
Solution Approach 2:
The invention inverts the conventional approach by connecting the transistors in series with their body terminals connected together, rather than connecting source to drain. This inversion of the typical parallel connection allows both transistors to conduct simultaneously in their respective directions, enabling bidirectional current interruption.
2Reliability
If two MOS transistors are placed in series to overcome polarity limitations, then the current interruption capability is improved, but the device complexity increases
Solution Approach 1:
The body terminals of the two MOS transistors are merged and connected together, forming a common node that serves as both the drain of one transistor and the source of the other. This merging reduces the number of external connections required and simplifies the overall device structure despite using two transistors.
Solution Approach 2:
The common body terminal connection serves multiple functions: it acts as the drain for one transistor, the source for the other transistor, and provides a reference potential for both devices. This multi-functionality reduces the complexity of external circuitry needed to control and monitor the switch operation.
3Speed
If a triggering circuit is added to store charges in the diodes, then the output signal sharpness and current flow during fast transitions is improved, but the device complexity increases
Solution Approach 1:
The triggering circuit pre-charges the intrinsic diodes of the MOS transistors before the main switching event occurs. By storing charges in the diodes in advance, the circuit ensures that when fast voltage transitions occur, the pre-charged diodes can immediately conduct, enabling sharp output signals without requiring complex external charging circuits.
Solution Approach 2:
The triggering circuit uses the inherent capacitance of the MOS transistor diodes themselves as the storage medium, rather than requiring external capacitors. The circuit leverages the existing parasitic elements of the transistors to achieve the desired fast switching performance, reducing the need for additional external components.
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
The configuration achieves a sharper output signal with higher current flow during fast transitions, maintaining reliability and simplicity, and effectively handles high-frequency input signals by utilizing stored charges in the diodes for stable conduction paths.
Implementation Method 1
A High Voltage switch configuration comprising two diodes in antiseries with a triggering circuit that stores charges in the diodes before applying the input signal
Implementation Method 2
two diodes in antiseries with a triggering circuit that stores charges in the diodes
Implementation Method 3
using a DMOS transistor, a third diode, and a resistor to generate a triggering current
Implementation Method 4
allowing for a conductive path to be formed independently of voltage polarity
Data Source
AI summary
A High Voltage switch configuration having an input terminal which receives an input signal and an output terminal which issues an output signal to a load. The High Voltage switch configuration comprises at least a first and a second diode, being placed in antiseries between said input and output terminals and having a pair of corresponding terminals in common, in correspondence of a first internal circuit node.