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As the drain voltage is increased for a junction FET in the pinch off region then the drain current?
Remains constant
What is cut off voltage of jfet if its pinch off voltage is 5v?
5v
Pinch off does not mean current off and pinch 0ff condition current zero?
as voltage on the gate increases it will reach a point where any further input will not effect further.
What is CMOS FET transistor?
CMOS stands for 'Complementary Metal Oxide Silicon' and is the construction method of the device. FET stands for 'Field Effect Transistor'. Although it is a transistor and is used in a similar fashion, it is totally different in the way it is controlled and biased. The pin outs are named differently. A bipolar transistor has a Base Emitter and Collector. A FET has a Drain Source and Grid. Current is controlled between the 'Source' and 'Drain' by altering the voltage on the grid. It works in a similar way to the old vacuum tube valves and is why the control is called a grid. It forms a 'pinch off' effect, in the path between the source and drain, instead of the depletion layer in a normal transistor.
What the differencebetween pinch off and cut off?
Pinch is temporary Cut is permanent
As the drain voltage is increased for a junction FET in the pinch off region then the drain current?
Remains constant
What is Cut-off voltage in fet?
fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
Fet in cut off voltage?
fet is a voltage controlled device...cut off voltage in fet refers to that voltage of the gate - source junction at which the current flow through channel is zero
What is cut off voltage of jfet if its pinch off voltage is 5v?
5v
Does pinch off voltage in jfet depends on temperature?
absolutelly
What is pinch off voltage?
Pinch off voltage is defined as the gate-to-source voltage at which drain-to-source current is zero.Proof:-(In the saturation region)IDS = IDSS [1- (VGS/VP)]2When IDS = O ,VGS = VP
What is pinch off?
Pinch off voltage is defined as the gate-to-source voltage at which drain-to-source current is zero.Proof:-(In the saturation region)IDS = IDSS [1- (VGS/VP)]2When IDS = O ,VGS = VP
Pinch off does not mean current off and pinch 0ff condition current zero?
as voltage on the gate increases it will reach a point where any further input will not effect further.
What happens in n channel at pinch off voltage that the drain current becomes constant?
At pinch off voltage, the channel is blocked at its maximum. (depletion region blocks almost entire channel, so no charge exchange). Therefore, no drain is flown through the channel.
How do you Find the pinch-off voltage for a MOSFET?
1. Look up the data sheet (specification sheet) and get it from there. 2. Set it up with a voltage supply from source to drain, apply a bias voltage to the gate, measure the bias voltage to just cut off the drain current.
How fet is used as vvr?
FET AS A VOLTAGE -VARIABLE RESISTOR (VVR):FET is operated in the constant current portion of its output characteristics for the linear applications .In the region before pinch off , where Vds is small the drain to source resistance rd can be controlled by the bias voltage Vgs.The FET is useful as a voltage variable resistor (VVR) or Voltage Dependent resistor.In JFET the drain source conductance gd = Id/Vds for small values of Vds which may be expressed as gd = gdo [ 1-( VgsVp)1/2 ] where gdo is the value of drain conductance when the bias voltage Vgs is zero.The variation of the rd with vgs can be closely approximated by rd = ro / 1- KVgs ro - drain resistance at zero gate bias and K constant dependent upon FET type.Small signal FET drain resistance rd varies with applied gate voltage Vgs and FET act like a VARIABLE PASSIVE RESISTOR.Advantagesof JFETVery high input impedance order of 100 ohmOperation of JFET depends on the bulk material current carriers that do not cross junctionsNegative temperature coefficientsVery high power gainSmaller size longer life and high efficiencyAc drain resistance rd it is the ratio of change in drain - source voltage to the change in drain current at constant gate source voltageTransconductance it is the ratio of change in drain current to the change in gate source voltageat constant drain source voltageAmplification factor it is the ratio of change in drain source voltage to the change in gate source voltage at constant drain current.
What is the operation of FET?
A Field Effect Transistor is a device with a single channel (conductor between two of the terminals). This channel is turned on an off by a voltage applied to the third terminal which is connected to the conducting channel in a J fet (junction Fet) or isolated from the channel in a Metal Oxide Semiconductor (MOS) fet. To keep the explanation simple, an enhacement mode MOS FET pulls charge carriers (electrons for N channel and holes for P channel) into the channel so its resistance decreases. This turns it on. By removing this voltage, charge carries move out of the channel and the FET turns off. It can be turned on partially by putting a small voltage on the control terminal called the GATE. In an N channel FET, the charge carriers (electrons) move from the SOURCE terminal (-ve) to the DRAIN terminal (+ve) when the FET is on. The voltage on the GATE is applied with respect to the SOURCE. In a P channel enhancement mode FET, charge carriers (holes) are also pulled into the channel in the same way but because the charge carriers are holes, the SOURCE is the +ve terminal and the DRAIN is the negative. The holes referred to are gaps in the crystal lattice of a substance like silicon which is doped (impurities added) with aluminum which has only 3 electrons in the outer shell instead of 4 like silicon. In a depletion mode FET, everything is the same except in reverse. Charge carriers are pushed OUT of the conducting channel.
