Bi-Directional MOSFET Switch Circuit for Leakage Suppression
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Solution Overview
Problem
Solid state switches, particularly MOSFETs, suffer from parasitic capacitance and current leakage that negatively impact measurement accuracy and power efficiency in precision measurement apparatuses and automated test equipment.
Innovation Solution
A bi-directional solid state switch design incorporating MOSFETs in series with buffers to provide current sources to their bulk terminals, reducing leakage via parasitic diodes by maintaining zero voltage differential across them, thereby improving measurement accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MOSFETs are used as solid state switches, then switching functionality is provided, but current leakage occurs at input and output terminals
Solution Approach 1:
A buffer circuit is introduced as an intermediary component between the input terminal and the bulk terminal of the MOSFET. This buffer acts as a mediator that provides a controlled current path to the bulk terminal, preventing leakage current from flowing through parasitic diodes while maintaining the switching functionality of the MOSFET.
Solution Approach 2:
The voltage differential across parasitic diodes is changed to zero by actively controlling the bulk terminal voltage through the buffer circuit. By adjusting the electrical parameter (voltage) at the bulk terminal to match the input terminal voltage, the parasitic diodes are prevented from conducting, thereby eliminating leakage current.
2Measurement precision
If leakage reduction techniques are applied, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The buffer serves as a simple intermediary that adds minimal complexity while effectively eliminating leakage. Rather than using complex compensation circuits or multiple additional components, a single buffer stage provides the necessary bulk terminal current, achieving leakage reduction with minimal increase in device complexity.
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 proposed design effectively eliminates or significantly reduces current leakage at the input and output terminals of the switch, enhancing power efficiency and measurement accuracy in precision instruments.
Implementation Method 1
Solid state switches, particularly MOSFETs, suffer from parasitic capacitance and current leakage
Implementation Method 2
reducing leakage via parasitic diodes by maintaining zero voltage differential across them
Data Source
AI summary
A solid state switch, comprising a first metal-oxide-semiconductor field-effect transistor (MOSFET). The first MOSFET has a first terminal, a second terminal, a bulk terminal and a gate terminal, and is configured to be switched between an on-state and an off-state. The solid state switch also comprises a second MOSFET in series with the first MOSFET. The second MOSFET has a first terminal, a second terminal, a bulk terminal, and a gate terminal. The second terminal of the first MOSFET is connected to the second terminal of the second MOSFET. The solid state switch comprises a first buffer comprises an output terminal coupled to the bulk terminal of the first MOSFET, and an input terminal coupled to the first terminal of the first MOSFET.