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To find out the qualitative response to changes in Vgs and Vds, consider Vgs =0. In response to a small applied voltage Vds, a n-channel JFET acts as a simple semiconductor resistor and Id increases linearly with Vds. With increasing current, the ohmic voltage drop between the source and the channel region reverse biases the junction and the conducting portion of the channel begins to constrict. because of the ohmic drop along the length of the channel itself, the constriction is not uniform but is more pronounced at distances father from the source. Eventually, a Vds is reached at which the channel is "pinched off". At this voltage, Id begins to level off. and approach a constant value. It is not possible for the channel to close completely and reduce Id to zero. If that were the case, then the ohmic drop required to provide the back biasing would be lacking.
Id is not equal to zero at Pinch off voltage.
Thus, pinch off voltage can be defined as the gate reverse voltage that removes all the free charge from the channel.
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How jfet works?
A Jfet works by applying voltage to the drain of the jfet. A jfet will then conduct across from drain to source.
What is cut off voltage of jfet if its pinch off voltage is 5v?
5v
What is bjt and jfet?
BJT is Bipolar junction transistor FET is Field effect Transistor It is a current controlled device It is voltage controlled device
Why must the gate to source voltage of an n channel Jfet always be zero or negative?
to made reverse bias junction between gate to source
Can jfet operate in enhancement and depletion mode?
No, jfet works only in depletion mode.
How jfet works?
A Jfet works by applying voltage to the drain of the jfet. A jfet will then conduct across from drain to source.
What is cut off voltage of jfet if its pinch off voltage is 5v?
5v
What are the applications of jfet?
• High Input Impedance Amplifier. • Low-Noise Amplifier. • Differential Amplifier. • Constant Current Source. • Analog Switch or Gate. • Voltage Controlled Resistor. • JFET as a Switch • JFET as a Chopper • JFET as a Current source • JFET as a Amplifier • JFET as a Buffer
Does pinch off voltage in jfet depends on temperature?
absolutelly
The voltage of a given common source JFET amplifier is depend on what?
amplification factor
What are current controllable devices?
BJT is a example for current controll device. And JFET is a voltage controlled device.
What are the advantages and disadvantages of JFET over BJT?
An advantage of JFET is stable high current operation. A disadvantage of JFET is low capacitance. An advantage of BJT is constant voltage operation. A disadvantage of BJT is low thermal conductance.
What type of transistor is a JFET?
JFET is a unijunction transistor.
What is the difference between jfet and mosfet?
1-BJT is bipolar while JFET is unipolar. 2-BJT has low input impedence while JFET has high input impedence. 3-JFET has low power discipation as compared to BJT. 4-JFET has low noise as compared to BJT. 5-BJT is current controlled while JFET is voltage controlled. 6-JFET is mostly used in digital circuits.
What is bjt and jfet?
BJT is Bipolar junction transistor FET is Field effect Transistor It is a current controlled device It is voltage controlled device
Why the n-jfet is operated with the negative voltage not the positive voltage?
In a JFET the only insulation between the gate and the channel is a reverse biased diode junction, if this junction becomes forward biased then the gate and channel are effectively shorted and the device no longer acts as a transistor (it will act as a forward biased diode instead). In the n-channel JFET, the gate is the P-side of this diode and the channel is the N-side of this diode. To keep this diode reverse biased (and the device operating as a transistor) therefor the gate MUST always be maintained at a voltage more negative than the most negative section of the channel.
Why must the gate to source voltage of an n channel Jfet always be zero or negative?
to made reverse bias junction between gate to source
