# MOSFET I-Vg Curve: Which Curve is Impossible?

• zhangz64
In summary, the conversation discusses the I - Vg curve for different MOSFETs and which curve is impossible for a MOSFET. The participants agree that curve #1 represents infinite gain and is clearly impossible. Curve #5 is also considered strange, possibly indicating reverse breakdown of the gate oxide. However, it is noted that tunneling is not possible with zero Vgs.
zhangz64
Homework Statement
Below graph shows the I - Vg curve for different MOSFET, which curve is impossible for MOSFET?
Relevant Equations
I - Vg
Homework Statement: Below graph shows the I - Vg curve for different MOSFET, which curve is impossible for MOSFET?
Homework Equations: I - Vg

I am inclined to select 1), as it is not likely to have a sharp transition from subthreshold to Quadritica region. However, graph 5 also looks strange, since it somehow shows current in at subthreshold region. I am therefore confused about whether it should be 1) or 5).

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I would agree. Could be either.

Tom.G said:
Curve #5 reminds one of reverse breakdown (due to Electron tunneling) of the gate oxide.
You can't tunnel with zero Vgs!

## What is a MOSFET I-Vg curve?

A MOSFET (metal-oxide-semiconductor field-effect transistor) I-Vg (current-voltage gate) curve is a graphical representation of the relationship between the voltage applied to the gate terminal of a MOSFET and the resulting current flowing through the device.

## Why is it important to analyze a MOSFET I-Vg curve?

Analyzing a MOSFET I-Vg curve allows us to understand the behavior of the device and its performance characteristics. It helps in determining the voltage levels required to turn the device on and off, as well as its saturation region and maximum current handling capabilities.

## Which curve is impossible in a MOSFET I-Vg curve?

In a MOSFET I-Vg curve, the curve representing a negative gate voltage (Vg) and a positive drain-source voltage (Vds) is impossible. This is because a negative gate voltage would result in the formation of a depletion region, preventing current flow through the device.

## What does the slope of a MOSFET I-Vg curve represent?

The slope of a MOSFET I-Vg curve represents the transconductance (gm) of the device, which is a measure of the change in drain current for a given change in gate voltage. It is an important parameter in determining the amplification and switching capabilities of the MOSFET.

## How can I use a MOSFET I-Vg curve in circuit design?

A MOSFET I-Vg curve can be used in circuit design to select the appropriate MOSFET for a specific application. It can also be used to analyze the stability and performance of the circuit, and to ensure that the device is operated within its safe operating limits.

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