Tell a Friend About CR4
Engineering Toolbar
Search GlobalSpec
Login | Register
Home | Communications & Electronics | Communications & Electronics | MOSFET

Previous in Forum: datasheet   Next in Forum: Power Amplifers for Mobile Communications
Close

Comments Format:






Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







7 comments
Subscribe Rate this Comments: Nested
AH_WA70
Associate

Join Date: Mar 2008
Posts: 52

MOSFET

06/14/2009 8:11 AM

I have a MOSFET that is always on and it off only when i give the gate ground and then returns on.Is this is working correctly? if yes i need explaination.
Send to a friend Digg this Add to del.icio.us
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Guest
#1

Re: MOSFET

06/14/2009 11:41 AM

Connect a 1 Kohm resistor from the gate to the ground and if it stays off it is OK. It seems that you either have a sensitive with a low capacitance GS or a very noisy environment.
AH_WA70
Associate

Join Date: Mar 2008
Posts: 52
#2
In reply to #1

Re: MOSFET

06/15/2009 2:56 AM

Thanks for your help
babybear
Guru

Join Date: Jun 2008
Location: USA/Europe
Posts: 3976
Good Answers: 70
#3
In reply to #2

Re: MOSFET

06/15/2009 3:20 AM

Hello AH WA70,

You may find 'noise' from the steel frame in a concrete flat or house could cause this as well.

bb

__________________
Take care, bb ----- >> "HEAR & you FORGET <-> SEE & you REMEMBER <-> DO & you UNDERSTAND" << =$=|O|=$= >> "Common Sense is Genius dressed in its Working Clothes" << <> [Ralph Waldo Emerson]
3
Randall
Guru

Join Date: Aug 2005
Location: Hemel Hempstead, UK
Posts: 1483
Good Answers: 41
#4

Re: MOSFET

06/15/2009 4:52 AM

As I understand it.

An enhancement mode MOSFET is normally off and turns on when you apply the appropriate voltage to the gate.

A depletion mode MOSFET is normally on and turns off when you apply the appropriate voltage to the gate.

I guess you've got a depletion mode device.

__________________
The early bird catches the worm, but, look what happens to the early worm: Alfred E. Neuman
Good Answer (Score 3)
No more Good Answers.
Rorschach
Guru
United States - Member - New Member Engineering Fields - Mechanical Engineering - New Member Engineering Fields - Petroleum Engineering - New Member Hobbies - Target Shooting - New Member

Join Date: Jan 2008
Location: Spring, Texas
Posts: 1217
Good Answers: 43
#5
In reply to #4

Re: MOSFET

06/15/2009 8:47 AM

GA my friend.

__________________
Who is John Galt?
kyilmaz
Participant

Join Date: Jun 2009
Posts: 3
#6

Re: MOSFET

06/18/2009 1:41 AM

You have N channel Mosfet with very little input capacitance.. Therefore input capacitance could be charged through drain to gate and gate to source capacitance and will stay on until gate capacitance is discharged . For that reason it is common practice to create low impedance between gate and source terminal when you do not have control voltage. Simplest way of doing this to connect 10K of lower resistor between these terminal

Kadir Yilmaz

www.globalpowerdesign.com
AH_WA70
Associate

Join Date: Mar 2008
Posts: 52
#7
In reply to #6

Re: MOSFET

06/22/2009 7:29 AM

Thanks for your help kyalmiz
7 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".
Copy to Clipboard

Users who posted comments:

AH_WA70 (2), babybear (1), Guest (1), kyilmaz (1), Randall (1), Rorschach (1)

Previous in Forum: datasheet   Next in Forum: Power Amplifers for Mobile Communications
You might be interested in: Power MOSFET, RF Transistors, MOSFET, Metal-oxide Semiconductor FET (MOSFET)


"Be the change you want to see in the world." -- Mahatma Gandhi

All times are displayed in US/Eastern (EST) (Register to change time zone)

©2005-2009 GlobalSpec. All rights reserved.
GlobalSpec, the GlobalSpec logo, SpecSearch, The Engineering Search Engine
and The Engineering Web are registered trademarks of GlobalSpec, Inc.
CR4 and Conference Room 4 are registered trademarks of GlobalSpec, Inc.
No portion of this site may be copied, retransmitted, reposted, duplicated or
otherwise used without the express written permission of GlobalSpec Inc.
350 Jordan Rd, Troy, NY, 12180

Got Something to Say?


Search this Forum
Communications & Electronics:

Search all of CR4

CR4 Sections
Automotive
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education
Electrical Engineering
Engineering Careers
General
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering

Site Indices
Forum Index
Blog Index
User Group Index
RSS Feeds
CR4 Store

CR4 FAQ
Site Glossary

Who's Online (132 right now)
Show Members