JFET is a/an ________ device.

The correct answer is option 3):unipolar

Concept:

• JFET is a unipolar-transistor, which acts as a voltage controlled current device and is a device in which current at two electrodes is controlled by the action of an electric field at a p-n junction.
• A JFET, or junction field-effect transistor, or JUGFET, is a FET in which the gate is created by reverse-biased junction

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• JFET is a three terminal device and since gate voltage controls the drain current, JFET is called as voltage controlled device.
• JFET’s have only depletion mode of operation. When there is no potential applied between gate and source terminals and a potential
• V_DD is applied between drain and source, then a current I0 flows from drain to source terminals at its maximum as the channel width is more.
• When the voltage applied between gate and source terminal VGG is reverse biased, this decreases the depletion width, thus the layers grows and the cross section of the channel decreases and hence the drain current ID also decreases.
• Thus drain current in JFET is controlled by changing the channel width. Gate source p-n junction is always reverse biased because if it is forward then all the channel current will flow to the Gate and not to the source, ultimately damaging JFET.