Thread: What is the difference between JFET and MOSFET?

What is the difference between JFET and MOSFET? Which one is better and how?

JFET use PN junction to provide high input impedance.

MOSFET use isolated gate to provide high input impedance.


best regards

Originally Posted by armohan

What is the difference between JFET and MOSFET? Which one is better and how?

MOS fets usually have lower gate leakage current. MOS fets are more readily available as high power/high current devices. MOS fets generally have higher forward transconductance (10s of Siemens vs fractions of Siemens). You must be careful not to forward bias the gate-source diode in a JFET. Providing reverse polarity (e.g a negative gate-source voltage on an N channel MOSFET) has no deleterious effect, as long as you stay within the device ratings.

The main different is that the JFET have a PN juntion for it have high input impedance.
The MOSFET have isolated gate with polysilicon.

Hi
There are many differences.
Biggest one is the topology.
MOS has higher input impedence.
JFET has higher current drive (transconductance), lower output impedance and can be used for high drive purposes. There are others also.
Try to grasp the difference in the functionality of both and they will popup automatically.

JFET use PN junction to controll the current ,Mos use isolated gate to controll current. In the ic world now, mos is dominent technology.

i think this web is hopeful for u:
http://www.phys.ualberta.ca/~gingric...es/node93.html

JFET is junction field effect transistor.and mosfet is metal semi oxide field effect transistor.i think mosfet is better than FET.

Added after 1 seconds:

JFET is junction field effect transistor.and mosfet is metal semi oxide field effect transistor.i think mosfet is better than FET.

There's another difference
In JFET increasing the gate to source voltage decreasing the source drain current it mean maximum source drain current at Vgs=0 volt
While at MOSFET increaing the gate voltage results to increasing the source drain current and it's calles enahancment mode

In MOSFET's the channel is made by the formation of the inversion layer and the charge on the inversion layer is controlled by the gate voltage.
While in JFET an already opened channel (when no gate voltage is applied) is controlled the formation of the depletion regions on the pn junctions betweengate and the bulk.
So JFET operates on the formation of the pn junctions while the MOSFET operates on the formation of the inversion layer.
MOSFET's are better due to the low lekages (greater controllability) and capability of having very high integration.