No, jfet works only in depletion mode.
It depends on: 1. technology, whether it's a JFET, enhancement-mode IGFET/MOSFET or depletion-mode IGFET/MOSFET, and 2. polarity, whether it's an N type or P type. More info needed for this one.
A depletion MOSFET is a MOSFET that is normally on. It outputs maximum current when the gate-source voltage is 0V. As the gate-source voltage increases, the drain-source channel becomes more resistive and the current decreases. An enhancement MOSFET has the opposite behavior. It is normally off. It outputs no current when the gate-source voltage is 0V. As the gate-source voltage increases, the drain-source channel becomes less resistive and the current increases.
The basic difference is between JFET and enhanced MOSFET,although the construction of JFET and depletion MOSFET is different but their most of the characteridtics are same,i.e shockly equation can be applied on both of them,but in JFET we cant give to gate voltage, the +ve value,because it does not works, but in depletion we can give,but some limited +ve value. Now enhanced MOSFET is different,shockly equation cant be applied.The transfer characteristics are purely in +ve Vg region. i.e for E-MOSFET Vg should be > 0,for its proper function.
A CPU operates in real mode and protected mode
N - channel enhancement mode device. by Engr. YuvZ
It depends on: 1. technology, whether it's a JFET, enhancement-mode IGFET/MOSFET or depletion-mode IGFET/MOSFET, and 2. polarity, whether it's an N type or P type. More info needed for this one.
MOSFET can be used in enhancement mode
A depletion MOSFET is a MOSFET that is normally on. It outputs maximum current when the gate-source voltage is 0V. As the gate-source voltage increases, the drain-source channel becomes more resistive and the current decreases. An enhancement MOSFET has the opposite behavior. It is normally off. It outputs no current when the gate-source voltage is 0V. As the gate-source voltage increases, the drain-source channel becomes less resistive and the current increases.
A depletion mode MOSFET is a FET that is on with no gate bias, and requires a negative bias (with respect to the source) to stop conducting. The channel is normally conductive and with a negative gate bias the channel becomes "depleted" of charge carriers, hence the name depletion mode MOSFET. This is contrary to enhancement type MOSFET's that are non conductive with zero volts gate bias and become conductive when there is a positive bias on their gate.
A Bipolar Junction Transistor(a.k.a. a BJT or BipolarTransistor) is an activesemiconductor deviceformed by twoP-N junctionswhose function is amplification of an electriccurrent.
Machine Mode
The basic difference is between JFET and enhanced MOSFET,although the construction of JFET and depletion MOSFET is different but their most of the characteridtics are same,i.e shockly equation can be applied on both of them,but in JFET we cant give to gate voltage, the +ve value,because it does not works, but in depletion we can give,but some limited +ve value. Now enhanced MOSFET is different,shockly equation cant be applied.The transfer characteristics are purely in +ve Vg region. i.e for E-MOSFET Vg should be > 0,for its proper function.
An e-mosfet is and "enhancement" mosfet. A d-mosfet is a "depletion" mosfet. These essentially show what mode the mosfet operates in when a voltage is applied to the gate. . An enhancement mode mosfet is normally non-conducting but conducts when the channel is enhanced by applying a voltage to the gate and pulling carriers into the channel. A depletion mode mosfet normally conducts but becomes more and more non-conducting as carriers are depleted or pulled out of the channel by applying a voltage. The polarity of the voltage depends on whether it is an N channel or P channel. P channel uses positively doped silicon while N channel uses negatively doped silicon. N channel fets are used wherever possible because N material conducts better than P material. There are basically two types of fet, the jfet and the mosfet. The jfet uses a single junction to control the channel hence draws some current. Bipolar transistors use two junctions. In the mosfet (Metal Oxide Semiconducting Field Effect Transistor) there is no such junction hence draw so little current for control purposes it can be regarded as zero. The gate is isolated from the channel by a very thin layer of metal oxide (usually chromium dioxide). An enhacement mode mosfet can be turned on by applying a voltage then removing the wire to the gate. The channel will then remain conducting for some time.
Depletion mode MOSFET is normally on device --vlsijp
JFET Construction and OperationA schematic representation of an n channel JFET is shown in Figure 118. An n-type channel is formed between two p-type layers which are connected to the gate. Majority carrier electrons flow from the source and exit the drain, forming the drain current. The pn junction is reverse biased during normal operation, and this widens the depletion layers which extend into the n channel only (since the doping of the pregions is much larger than that of the n channel). As the depletion layers widen, the channel narrows, restricting current flow. Figure 118: n-channel JFET structure.When , there is little voltage drop along the length of the channel, and the depletion regions are parallel, Figure 119. As vGS is increased negatively, they eventually touch reducing iD to zero. The value of vGSat which this occurs is called the pinch-off voltage, Vp (or vGS(off)).Figure: n-channel JFET structure for showing parallel depletion regions.When , there is a voltage drop along the length of the channel, and the depletion regions are no longer parallel, but are closer together towards the drain, Figure 120. As vDS is increased, they will touch (pinch-off) towards the drain, and the drain current iD can increase no longer. At the threshold of pinch-off, vGS-vDS=Vp. As vDS is further increased, iD remains constant, and the JFET is in its current saturationregion, the normal mode of operation. (This constant current region is a characteristic feature of any transistor, FET or BJT.) The channel shape remains unchanged, with a small region of touch near the drain, and further increases in vDS occurs across this small region.Figure: n-channel JFET structure for showing non-parallel depletion regions.JFETS are high input impedance devices, and so (due to the reverse bias pn junctions).
depletion layer depletion zone juntion region space charge region bipolar transistor field effect transistor variable capacitance diode
N-channel enhancement mode device