# What is the difference between JFET and MOSFET?

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#### pavanvkulkarni

##### Newbie level 4
JFET vs MOSFET

Hi all,
I actually have 2 queries though they may sound very naive.... i posted this in hope of getting a very clear picture

1) What is the difference between JFET and MOSFET in a very very basic sense... And when MOSFET has so many advantages, do we really have to use JFET..?

2) We know that the clock source in most cases is a "crystal"... How does this crystal actually generate the clock... ?? What type of crystals are actually used??

#### pthoppay

##### Member level 5
Re: JFET vs MOSFET

1) What is the difference between JFET and MOSFET in a very very basic sense... And when MOSFET has so many advantages, do we really have to use JFET..?

No, presently I have never seen anyone using JFET, it is mostly extinct.

2) We know that the clock source in most cases is a "crystal"... How does this crystal actually generate the clock... ?? What type of crystals are actually used??

Because, crystal reference clock are very stable, they work on the principle of piezoelectric effect, the crystal are made up of quartz till 20-32 MHz, overwhich they operate in overtones (not in digital circuits).

Regards,
Prakash.

#### sec

Re: JFET vs MOSFET

JFET as I know is a variable resistor
the MOSFET create a field that attract the electron on the the zone between drain and source so the signal is better when tere is current in the gate. It also got "memory" because on the inductance and capacitor effect

#### gte582w

##### Member level 5
Re: JFET vs MOSFET

1. JFET is very good for low-noise application

2. the equivalent electrical model for crystal is some combination of
L's and C's, it can be embedded in positive feedback active circuit
(used to compensate the loss) to generate a stable oscillation frequency,
such as colplitts etc.

#### Verba

##### Member level 5
JFET vs MOSFET

JFET is good for low noise applications, for low capacitance and high resistance input.

#### bunalmis

##### Full Member level 5
Re: JFET vs MOSFET

JFET has low GS resistance. (GS has junction)
MOSFET high GS resistance (GS no junction)

JFET for small voltage and current applications. (Usually you can not find power JFET at the market)

MOSFET has reverse body diode. JFET hasn't.

#### Gundam001

##### Full Member level 1
Re: JFET vs MOSFET

MOSFET
Code:
http://en.wikipedia.org/wiki/MOSFET

JFET
Code:
http://en.wikipedia.org/wiki/JFET

Crystal
Code:
http://en.wikipedia.org/wiki/Crystal_oscillator

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