# Define MOSFET and igbt

#### Tom gayle

Joined Sep 20, 2021
83
Hey,I can't understand what basically the MOSFET and igbt?

#### ronsimpson

Joined Oct 7, 2019
3,045
A " bipolar transistor" has an input "Base" which needs current, not voltage, to turn on the part.
A MOSFET has a "Gate" which turns on by voltage and not current.
A IGBT is an insulated-gate bipolar transistor. The Gate is like a MOSFET and the output is like a bipolar transistor.

#### crutschow

Joined Mar 14, 2008
34,464
A " bipolar transistor" has an input "Base" which needs current, not voltage, to turn on the part.
You likely will get some flack about the BJT not needing base voltage, so let's just add that the the base-emitter has a voltage equal to the forward biased base-emitter diode at its operating base current (typically about 650-700mV).
We can leave the argument from the pedantic types about the BJT technically being a voltage operated device for another time.

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#### Ian0

Joined Aug 7, 2020
9,842
An IGBT is a bit like a Sziklai pair made from one MOSFET and one PNP Bipolar transistor.
What is very confusing is that the Emitter terminal of the IGBT actually connects to the collector of the PNP transistor, and the collector terminal of the IGBT connects to the emitter of the PNP transistor.
The transistor relies on the the resistor to turn it off, so that's why an IGBT takes until a week next tuesday to turn off.

#### ronsimpson

Joined Oct 7, 2019
3,045
IGBT takes until a week next tuesday to turn off
IMO, a IGBT is for people that don't know how to turn on/off a power transistor.
A MOSFET "Gate" is simple. 12V=on, 0V=off.
A power transistor is more complicated. Applying 0.65V probably will not work.

#### neonstrobe

Joined May 15, 2009
190
Do you know the basics of how a diode works?
Or a bipolar transistor?

#### Tom gayle

Joined Sep 20, 2021
83
Do you know the basics of how a diode works?
Or a bipolar transistor?
Diode is used to flow of current in one direction.And I don't know about bipolar transistor...

#### Tom gayle

Joined Sep 20, 2021
83
An IGBT is a bit like a Sziklai pair made from one MOSFET and one PNP Bipolar transistor.
View attachment 261073What is very confusing is that the Emitter terminal of the IGBT actually connects to the collector of the PNP transistor, and the collector terminal of the IGBT connects to the emitter of the PNP transistor.
The transistor relies on the the resistor to turn it off, so that's why an IGBT takes until a week next tuesday to turn off.
What is bipolar transistor ? can anybody help me?

#### crutschow

Joined Mar 14, 2008
34,464

#### Ian0

Joined Aug 7, 2020
9,842
What is bipolar transistor ? can anybody help me?
ALL transistors use the voltage between gate/base and source/emitter to control the flow of current between drain/collector and source/emitter.

In Bipolar transistors you have to provide a continuous base current because there is a diode between base and emitter.
In FETs you have only to provide short current pulses into the gate because there is a capacitor between gate and source

#### Ya’akov

Joined Jan 27, 2019
9,170
This video covers the differences. Though it concentrates on IGBTs it gives a good explanation of the differences and why you might choose one over the other. It includes both basic information and a bit of more technical information. If you watch it and have questions about the content in it, I would be happy to answer those (an no doubt others would be too.)

My problem with your original question is that I have no idea what you do and don't know, or why you are asking it, so giving answers is like shooting in the dark.

#### Tom gayle

Joined Sep 20, 2021
83
This video covers the differences. Though it concentrates on IGBTs it gives a good explanation of the differences and why you might choose one over the other. It includes both basic information and a bit of more technical information. If you watch it and have questions about the content in it, I would be happy to answer those (an no doubt others would be too.)

My problem with your original question is that I have no idea what you do and don't know, or why you are asking it, so giving answers is like shooting in the dark.

Nope, I just wanna ask it.i Haven't know what are those components.so I just ask...

#### Ya’akov

Joined Jan 27, 2019
9,170
Nope, I just wanna ask it.i Haven't know what are those components.so I just ask...
Nope? What are you answering "nope" to?

#### Tom gayle

Joined Sep 20, 2021
83
Nope? What are you answering "nope" to?