What is the Effect of Floating MOSFET Base Plate?

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SUMMARY

Leaving a MOSFET base plate floating can lead to potential voltage breakdown and increased susceptibility to electrostatic discharge (ESD). Typically, the substrate is connected to the source terminal to prevent these issues and maintain isolation through reverse biasing of the PN contact layer. The specific voltage acquired by a floating base plate depends on the MOSFET model and the circuit configuration. For accurate guidance, users should provide detailed information such as the MOSFET part number and circuit schematic.

PREREQUISITES
  • Understanding of MOSFET operation and configurations
  • Familiarity with electrical isolation techniques
  • Knowledge of electrostatic discharge (ESD) prevention methods
  • Ability to read and interpret electronic schematics
NEXT STEPS
  • Research the implications of floating substrates in MOSFETs
  • Learn about the body effect in MOSFETs and its impact on performance
  • Explore ESD protection strategies for semiconductor devices
  • Study specific MOSFET part numbers and their recommended configurations
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Electrical engineers, circuit designers, and anyone involved in semiconductor device design and optimization will benefit from this discussion.

EE4me
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Are there any downsides to leaving a MOSFET base plate floating?
My specific system will benefit from having the MOSFET base plate floating. Are there any downsides to leaving a MOSFET base plate floating? Are there any reasons not to?
 
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EE4me said:
Are there any downsides to leaving a MOSFET base plate floating?
Base plate ? = body ? substrate ?
It is usual to connect the substrate to the source terminal so as to prevent voltage breakdown, ESD, and to maintain isolation by reverse biasing the PN contact layer on the substrate.
What voltage will it acquire if it is left to float ?
https://en.wikipedia.org/wiki/MOSFET#Body_effect
 
Last edited:
This depends on the specific device and the circuit/application. Usually the "base plate" is connected to the drain, so it won't be truly floating. You won't get a useful answer from us without providing more information. You could start with a schematic, the part number of the MOSFET, and a description of what you want your circuit to do.
 

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