In a mosfet channel when the channel is pinched off, the current is crossing (passing)?

[stackprogramer]

In a mosfet channel when the channel is pinch off,the current is crossing(passing)?

in a mosfet channel when the channel is pinch off,the current is crossing(passing)?
the connection is possible between source and drain?
we now this aera is Depletion?
does it realated to tunneling phenomenon in mechanic Quantum?
please explain .


thanks very mcuh for your replies.

 

[FvM]

Re: In a mosfet channel when the channel is pinch off,the current is crossing(passin

Drain-bulk current should be sufficient to explain off-state current flow.

 

[stackprogramer]

Re: In a mosfet channel when the channel is pinch off,the current is crossing(passin

i finded the a answer from other site,

Even though the conductive channel formed by gate-to-source voltage no longer connects source to drain during saturation mode, carriers are not blocked from flowing. Considering again an n-channel enhancement-mode device, a depletion region exists in the p-type body, surrounding the conductive channel and drain and source regions. The electrons which comprise the channel are free to move out of the channel through the depletion region if attracted to the drain by drain-to-source voltage. The depletion region is free of carriers and has a resistance similar to silicon. Any increase of the drain-to-source voltage will increase the distance from drain to the pinch-off point, increasing the resistance of the depletion region in proportion to the drain-to-source voltage applied. This proportional change causes the drain-to-source current to remain relatively fixed, independent of changes to the drain-to-source voltage, quite unlike its ohmic behavior in the linear mode of operation. Thus, in saturation mode, the FET behaves as a constant-current source rather than as a resistor, and can effectively be used as a voltage amplifier. In this case, the gate-to-source voltage determines the level of constant current through the channel.

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i finded that other phenomenon,that channel lenght modulation,this reality causes the current no should accurately fixed
a little changed.
thanks very much for your attention

 

[erikl]

Re: In a mosfet channel when the channel is pinch off,the current is crossing(passin

Drain-bulk current should be sufficient to explain off-state current flow.

Not off-state, saturation mode is meant: Vgs > Vth , and Vds > Vgs - Vth (pinch-off).

 

[FvM]

Re: In a mosfet channel when the channel is pinch off,the current is crossing(passin

Right of course, I didn't notice Vgs > Vth.