Junction Field Effect Transistor

Question

In terms of drain and source current P-channel JFET is similar to which BJT ? npn or pnp?

kindly tell me about BJT's and FET's relation?

Answer 1

The JFEt Transistor is very similar to a regular transistor as far as hooking it up goes. Common Emitter = Common Source Configuration. The Main difference in operation Of a JFET to a transistor, The transistor relies on current to operate the base while the JFET gate is controlled by voltage. As someone above stated it is very similar to a tube amplifier but with much less voltage on the Drain. What is it good for, inputs that have very little current but have voltage. I have used it for timing circuits, charging a capacitor and resistor combination, since the gate does not draw much current, the gate will not bleed down the voltage on the capacitor as it charges. 555 Use FETs It has and may still to used in Tuner RF stages as it will not overload with a large signal as a transistor would, acting as a diode detector and let the signal from a strong station override a more distant station. If you want to design something I would use a MOSFET instead, VN2222 is a low level N channel. More commonly used today. Same principle

Answer 2

In terms of polarity, a P-channel JFET is sort of similar to a PNP transistor. A N-channel JFET is sort of similar to a NPN transistor.

I say "sort of similar" because the source lead of a P-channel JFET has the same polarity as the emitter of a PNP transistor. But that's about where the similarities end.

Answer 3

There are "PNP" and "NPN" varieties of both.

BJT:
Current-controlled
Can be turned "partially on"
Constant, linear power loss while conducting

FET:
Voltage-controlled
ON or OFF
Power loss during switching; minimal while on
RDS(on) typically measured in mOhm's