Because for creating channal we need voltage at gate if there is no voltage at ate then VGS=0 this mean no amplificatiion can be done.
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∙ 11y agoIt 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.
forward bias
it depends on the type of the circuit you are analyzing..it could be a voltage divider, emitter follower, be specific on what type of circuit and maybe i can help you aobut this question.
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.
Crystal diode for a p-type semiconductor and n-type semiconductor formation of the pn junction, in its interface on both sides of a space-charge layer, and has a self-built electric field. When there is no applied voltage, as pn junction on both sides of carrier concentration caused by the proliferation of poor self-built electric current and drift arising from the current equivalent and the balance of power in the state. When the outside world a positive bias voltage, electric and outside the field of mutual self-suppression role of the Consumers carrier increase from the current spread of the forward current. When the outside world a reverse bias voltage, external electric field and to further strengthen self-built electric field, in a certain form of reverse voltage and reverse bias voltage value unrelated to reverse saturated current I0. When the reverse voltage applied to a certain high level, pn junction in the space charge of the electric field strength to achieve the critical values of the double-carrier process, a large amount of electronic hole right, had a great numerical breakdown of the reverse current, Breakdown phenomenon known as diodes.
With the E-MOSFET, VGS has to be, 'greater than VGS(th) to get any drain current at all. Therefore, when E-MOSFETs are biased, self-bias, current-source bias, and zero bias cannot be used because these forms of bias depend on the depletion mode of operation. This leaves gate bias, voltage-divider bias, and source bias as the means for biasing E-MOSFETs.
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.
MOSFET stands for Metal Oxide Semiconductor Field Effect Transistor, It is broadly Classified into Depletion type MOSFETS and Enhancement type MOSFETS. Depletion type MOSFETS are further classified into P-Channel and N-Channel Depletion type MOSFET, Similarly Enhancement type MOSFETS are further classified into P-Channel and N-Channel Enhancement type MOSFET.
bnder
To make a depletion MOSFET, the channel must be doped with carriers; this is in total opposite to an enhancement MOSFET which avoids carriers in the channel at all cost. (because the carriers in the channel become the subthreshold leakage current) Since you need to pinch the channel against the substrate to guarantee to turn off the channel completely, there must be a reverse bias between the substrate and the source terminal. As a result, the source terminal of an N type depletion MOSFET must be tied to Vdd. This is also a complete opposite to enhancement MOSFET. In order to turn off the channel quickly, the carriers in the channel of depletion MOSFET are usually planted shallowly. This is a drastically different from enhancement MOSFET that carriers must be planted deeply into source terminal in order to support a large diffuse current. The construction of depletion MOSFET thus requires far less diffusion time than enhancement MOSFET.
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.
forward bias
forward bias Type your answer here...
This arrangement is called SELF-BIAS. Now, if an increase of temperature causes an increase in collector current, the collector voltage (VC) will fall because of the increase of voltage produced across the load resistor (RL). ... One of the most widely used combination-bias systems is the voltage-divider type
bias
it depends on the type of the circuit you are analyzing..it could be a voltage divider, emitter follower, be specific on what type of circuit and maybe i can help you aobut this question.
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