MOSFET VGS

[Kevin Weddle]

How can MOSFET's be used in low voltage circuits when their VGS is high?

 

[Hero999]

It depends on what you mean by low or high voltage?

Technically low voltage is any voltage below 1.5kVDC or 1kVAC which is much higher than the voltage rating of a typical MOSFET.

The short answer is the gate voltage must be high enough to ensure the MOSFET can pass the required drain current.

 

[Kevin Weddle]

A typical MOSFET can have a VGS of 3 volts. A bipolar transistor has a base emitter bias of about .7 volts. The emitter voltage is often low with both transistors, so a 5 volt voltage source would have less than 2 volts to bias a MOSFET.

 

[Hero999]

Keven,
Why do you keep making nonsensical statements? If you want to ask a question, ask one. If you want confirmation as to whether a statement you've made is true or not, end the sentence with a question mark.

A typical MOSFET can have a VGS of 3 volts. A bipolar transistor has a base emitter bias of about .7 volts. The emitter voltage is often low with both transistors,

That makes no sense, a MOSFET doesn't have an emitter.

so a 5 volt voltage source would have less than 2 volts to bias a MOSFET.

That doesn't make any sense either, 5V on a MOSFET's gate (relative to its source) is 5V. The drain current and voltage vs the gate voltage curves are given on the datasheet. I think you should read a datasheet for a typical MOSFET before posting again.