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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.
How FET is used as a voltage variable resistor?
A Field-Effect Transistor (FET) can function as a voltage variable resistor by utilizing its gate voltage to control the channel conductivity. By applying a varying voltage to the gate, the FET alters the channel's resistance, allowing it to act like a variable resistor. This property is particularly useful in applications like analog signal processing and voltage-controlled amplifiers, where precise control of resistance is required. The FET's high input impedance also minimizes the loading effect on the preceding circuit, making it an effective choice for such applications.
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.
What is 0.37v and 0.63v in RC circuit?
0.63 is the knee voltage & 0.37 is the cutoff voltage
How do you measure DC voltage in multistage FET amplifier?
To measure DC voltage in a multistage FET amplifier, you should first ensure the device is powered on and the input signal is disconnected to avoid interference. Use a digital multimeter (DMM) set to the DC voltage measurement mode. Connect the positive lead of the DMM to the point where you want to measure the voltage (e.g., the drain or gate of a FET) and the negative lead to the common ground of the circuit. This will provide you with the DC voltage level at that specific point in the amplifier circuit.
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.
