Floating Body Contact Circuit for MOSFET ESD and Switching Speed

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Solution Overview

Problem

Semiconductor devices, particularly MOSFETs on SOI and SOS substrates, face challenges in improving ESD performance and switching speed due to accumulated charge, which introduces harmonic distortion, intermodulation distortion, and reduces breakdown voltage, while larger gate resistors enhance ESD handling but increase switching time and insertion loss.

Innovation Solution

Incorporating an accumulated charge sink (ACS) and a switchable gate resistor module (SGRM) to manage accumulated charge and optimize gate resistance, allowing for improved ESD handling and switching speed by dynamically adjusting resistance based on operational requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If larger gate resistors are used to enhance ESD handling, then ESD performance is improved, but switching time increases and insertion loss increases

Engineering Contradiction:

ImproveESD performanceVSAvoidswitching time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the gate resistance variable rather than fixed. A switchable gate resistor module is implemented that can dynamically adjust the gate resistance value based on operational conditions. During ESD events, higher resistance is applied to improve ESD handling, while during normal switching operations, lower resistance is used to maintain fast switching speed and low insertion loss.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the resistance parameter of the gate resistor from a fixed value to a variable value that can be adjusted based on operational requirements. An accumulated charge sink is also employed to actively manage charge accumulation in the body, allowing the device to maintain optimal performance across different operating conditions by adjusting electrical parameters in real-time.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If accumulated charge is present in floating body devices, then device operation is enabled, but harmonic distortion increases, intermodulation distortion increases, and breakdown voltage decreases

Engineering Contradiction:

Improvedevice operationVSAvoidharmonic distortion, intermodulation distortion, reduced breakdown voltage

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the harmful accumulated charge from the floating body through an accumulated charge sink. This sink provides a dedicated path for charge to be removed from the body, separating the charge accumulation function from the normal device operation. By extracting the harmful charge carriers, the device maintains good linearity and breakdown voltage while still enabling proper operation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The accumulated charge sink acts as an intermediary element between the floating body and the charge carriers. It mediates the charge management by providing a controlled path for charge removal, allowing the device to operate with minimal accumulated charge and thus reducing harmonic and intermodulation distortion while maintaining breakdown voltage.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10256287B2Floating body contact circuit method for improving ESD performance and switching speed

Publication Date: 2019.04.09 PSEMI CORP

AI summary

Embodiments of systems, methods, and apparatus for improving ESD performance and switching time for semiconductor devices including metal-oxide-semiconductor (MOS) field effect transistors (FETs), and particularly to MOSFETs fabricated on Semiconductor-On-Insulator (“SOI”) and Silicon-On-Sapphire (“SOS”) substrates.