High Voltage Switching Circuit Using MOSFET Body Diode
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Solution Overview
Problem
Existing high voltage switching circuits for PiN/NiP diodes in RF applications are complex and expensive due to the need for complex gate driver circuits to manage high voltage MOSFETs, especially when switching between high and low voltage states at high speed and low frequency.
Innovation Solution
A switching circuit that includes a driver circuit with optocoupler phototransistors and a MOSFET, allowing asynchronous switching between high and low voltage inputs on a common output, eliminating the need for floating drive circuits and simplifying the design, enabling quick switching between voltage modes without special gate charging circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If complex gate driver circuits are used to manage high voltage MOSFETs for high speed switching, then switching speed is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the high voltage switching function from the MOSFET gate driver circuit by using the body diode of the MOSFET as the primary switching element. The gate driver only needs to provide simple forward bias voltage to turn on the body diode, eliminating the need for complex high voltage gate drive circuitry while maintaining fast switching capability.
Solution Approach 2:
The MOSFET body diode serves its own switching function without requiring external high voltage drive circuitry. The diode naturally switches on when forward biased and switches off when reverse biased, providing self-service switching action that eliminates the need for complex gate driver circuits designed for high speed operation.
2Reliability
If floating drive circuits are used to maintain high voltage MOSFET on-state, then high voltage switching capability is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the floating drive circuit requirement by extracting the switching function to the body diode. The MOSFET is used only in its diode mode, which eliminates the need for floating gate drive circuits to maintain the on-state, thereby reducing manufacturing complexity and cost.
Solution Approach 2:
Instead of using the MOSFET in its typical enhanced mode requiring floating gate drive, the patent inverts the approach by using the MOSFET body diode in its natural rectifying mode. This inversion eliminates the need for complex floating drive circuits while maintaining high voltage switching capability.
3Speed
If specialized gate driver circuits are used for high frequency switching, then high speed switching is achieved, but device complexity increases for low frequency applications
Solution Approach 1:
The patent creates a universal switching solution that works for both high frequency and low frequency applications by using the MOSFET body diode. The same simple circuit configuration provides fast switching capability across all frequency ranges, eliminating the need for specialized high frequency gate driver circuits.
Solution Approach 2:
The body diode provides self-service switching that naturally adapts to any frequency requirement without needing specialized driver circuitry. The diode switches on and off based on the applied voltage polarity, providing universal functionality for both high and low frequency applications with a single simple circuit design.
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 solution reduces manufacturing costs and space requirements, achieving high speed switching within 15 μsec or less, improving the efficiency and reliability of RF impedance matching networks by simplifying the circuitry and reducing switching losses.
Implementation Method 1
A switching circuit includes an optocoupler phototransistor and a metal oxide semiconductor field effect transistor (MOSFET)
Data Source
AI summary
A switching circuit includes: an electronic switch comprising one or more diodes for switching a capacitor within an electronic variable capacitor array; a first power switch receiving a common input signal and a first voltage input; and a second power switch receiving the common input signal and a second voltage input, wherein the second voltage input is opposite in polarity to the first voltage input, and the first power switch and the second power switch asynchronously connect the first voltage input and the second voltage input, respectively, to a common output in response to the common input signal, the one or more diodes being switched according to the first voltage input or the second voltage input connected to the common output.