BJT is a current controlled device because its output current is dependent upon the current in the base while for FET it is controlled by the voltage at the gate terminal of the transistor.
BJT is a current controlled device because its base current is not zero while for a FET the gate current is zero
Because the operation of the transistor is determined by the current at the base. the principle equations of BJT operation are:
Ic = h*Ib ,and
Ie=Ib+Ic
thus device operation is controlled by the input current.
a bjt is a current controlled device as the base current controls the output current,i.e the collector current
FET is not current controlled device. FETs are voltage controlled device as depletion region around the junction is function of reverse voltage applied to the GATE of JFET
Because the bipolar junction transistor changes the signal in response to an outside input.
when BJT is in steady state (wher we controle the current di/dt) control the currnt and voltage are applied at input (base) o juntion was establish
When bipolar junction transistor(BJT) is operated under proper biasing large current flows through the BJT,thus it is called current operated device.
BJT is Bipolar junction transistor FET is Field effect Transistor It is a current controlled device It is voltage controlled 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
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.
Power FET
diodes
BJT is Bipolar junction transistor FET is Field effect Transistor It is a current controlled device It is voltage controlled 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
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 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 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.
The FET is a semiconductor device with the output current controlled by an electric field. Since the current is carried predominantly by one type of carriers, the FET is known as a unipolar transistor.
A FET is just a material either N or P whereby a restriction is applied by a field volts impressed on the material as restricting the current flow or allow the current flow
FET's (field effect transistors) are unipolar devices because unlike BJT's that use both electron and hole current, they operate only with one type of charge carrier. BJT is a current-controlled device; that is the base current controls the amount of collector current. FET is a voltage-controlled device, where voltave between two of the terminals (gate and source) controls the current through the device. BJT's have a low input impedance ( ~1k -3k ohms), while FET's have a very high input impedance (~10^11 ohms). Consequently FET's have a lower power consumption. BJT's produce more noise than FET's . FET's have a slower switching speed . BJT's are subject to thermal runway while FET's are immune to this problem. BJT's have a higher cutoff frequencey and a higher maximum current then FET's. FET's are easy to fabricate in large scale and have higher element density the BJT's.
Power FET
A FET is called a square-law device because of the relationship of ID to the square of a term containing VGS.
Gate
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.