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For a JFET, when VDS is increased beyond the pinch off voltage, the drain current

For a JFET, when VDS is increased beyond the pinch off voltage, the drain current Correct Answer Remains constant

Junction Field Effect Transistor (JFET):

They have no PN-junction but instead has a narrow piece of high resistivity semiconductor material forming a “Channel” of either N-type or P-type silicon for the majority carriers to flow through with two ohmic electrical connections at either end commonly called the Drain and the Source respectively.

There are two basic configurations of junction field effect transistor, the N-channel JFET and the P-channel JFET.

  • The N-channel JFET’s channel is doped with donor impurities meaning that the flow of current through the channel is negative (hence the term N-channel) in the form of electrons.
  • The P-channel JFET’s channel is doped with acceptor impurities means that the flow of current through the channel is positive (hence the term P-channel) in the form of holes.
  • N-channel JFET’s have a greater channel conductivity (lower resistance) than their equivalent P-channel types, since electrons have a higher mobility through a conductor compared to holes. This makes the N-channel JFET’s a more efficient conductor compared to their P-channel counterparts.

 

There is a third electrical connection which is called the Gate terminal and this can also be a P-type or N-type material forming a PN-junction with the main channel.

The voltage at which the channel closes is called the “pinch-off voltage”, ( VP ).

When VDS is increased beyond the pinch off voltage, VGS (Gate Voltage) controls the channel current and VDS has little or no effect ie: remains constant.

Related Questions

Consider the following statements regarding n-channel JFET: 1. The maximum drain current IDSS occurs when gate-to-source voltage VGS = 0 V and drain-to-source voltage VDS ≥ |VP|. (VP is pinch-off voltage). 2. For gate-to-source voltage VGS less than the pinch-off level, the drain current is 0 A. 3. For all levels of VGS between 0 V and the pinch-off level, the current ID will range between IDSS and 0 A, respectively. which of the above statements are correct ?
Consider the following statements regarding JFET: 1. The relationship between the drain current and gate-to-source voltage of a JFET is a nonlinear. 2. The minimum current for JFET occurs at pinch-off voltage defined by VGS = VP. 3. A current controlled device is one in which a current defines the operating conditions of the device. Which of the above statements are correct?
When VDS is the drain voltage and VDS(max) is the maximum drain voltage, the JFET will breakdown if:
When an N-channel JFET reaches pinch-off, the increase in the drain to source voltage results in shifting of the pinch-off position towards the ___________
When drain voltage equals the pinch-off-voltage, then drain current ___________ with the increase in drain voltage
Assertion (A): A JFET can be used as a current source.Reason (R): In beyond pinch off region the current in JFET is nearly constant.
Assertion (A): A JFET can be used as a current source.
Reason (R): In beyond pinch off region the current in JFET is nearly constant.
When the voltage across the drain and the source (VDS) is increased from a small amount (assuming that the gate voltage, VG with respect to the source is higher than the threshold voltage, Vt), then the width of the induced channel in NMOS (assume that VDS is always small when compared to the Vov)
In a power MOSFET, pinch-off occurs when (VDS is the drain to source voltage, VGS is the gate to source voltage VT is the threshold voltage):
In a JFET, when drain voltage is equal to pinch-off voltage, the depletion layers