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Other name of voltage to current converter?
a FET, or Feild Effect Transistor. In a FET, the value of the current depends upon the value of the voltage applied at the gate and drain so it is known as a voltage controlled device. For example: In a MOSFET the current from drain to source depends upon the width of the depletion layer which in turn depends upon the voltage applied on the gate.
What happens if very high voltage is applied to the gate of the n and p channel MOSFET?
punchthru, resulting in destruction of the FET
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.
What is the voltage gain of the FET amplifier?
It can be answered in two ways : 1. ratio of output & input voltages [Vout / Vin] i.e Drain voltage(Vds)/Source voltage(Vs). 2. multiplication of trans-conductance & drain resistance .
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.
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 are voltage controlled devices?
FET
Why the voltage gain of an FET amplifier is generally less than that obtained using BJT amplifier?
A FET (Field Effect Transistor) is mainly used when the input signal needs to be isolated from the output. A FET has a very high input resistance, so very little current is required from the input. Voltage gain is not the main objective when using a FET.
What is 0.37v and 0.63v in RC circuit?
0.63 is the knee voltage & 0.37 is the cutoff voltage
How biasing of FET differs from biasing of BJT?
in BJT forwardbiasing & reverse biasing are carried out but in FET voltage divider biasing &self biasing are carried out.
Why is it thatFET is called a voltage operated device?
since in an FET the value of the current depends upon the value of the voltage applied at the gate and drain...so it is known as voltage controlled device.. for example..in a mosfet..the current from drain to source depends upon the width of the depletion layer..which in turn depends upon the voltage applied on the gate.. so that is the reason
A junction FET can be used as a voltage variable resistor at which stage?
nnm,n,n,mn
Other name of voltage to current converter?
a FET, or Feild Effect Transistor. In a FET, the value of the current depends upon the value of the voltage applied at the gate and drain so it is known as a voltage controlled device. For example: In a MOSFET the current from drain to source depends upon the width of the depletion layer which in turn depends upon the voltage applied on the gate.
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?
Cutoff voltage is the point at which the battery is fully discharged. This is usually the point at which the device will shut itself off.
What is FET?
FET is abbreviation of Field Effect Transistor. This is a transistor in which current is controlled by voltage only and no current is drawn. It is a high input impedence device and is used in computers, telecommunication and control circuits. This transistor is better in certain parameters as compared to BJT, that is Bipolar Junction Transistor.
What happens if very high voltage is applied to the gate of the n and p channel MOSFET?
punchthru, resulting in destruction of the FET
