# Power FET Question - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

krc
Post subject: Power FET question Posted: Fri Apr 21, 2006 10:42 pm

Lieutenant

Joined: Fri Apr 21, 2006 10:34 pm
Posts: 3
hi...i am student and this is simple question: i have a power fet that need to be biased at 12 A of current for its Id biasing.however the current source outputs 25 A of current. since i don't have resistor that can handle this level of current what can i do so that only 12 A of current goes in the drain of the current? thanx

kc

Top

IR
Post subject: Posted: Mon Apr 24, 2006 4:07 pm

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello,

The current passing through the FET's drain is set by the minimal load that you will connect to your circuit. There are many current limiting circuits relatively easy to implement, and you need to use one in your design. Look in Google there are many applications for such circuits.

Here is just a single example from a quick search in Google:

Good luck!

_________________
Best regards,

- IR

Top

Jeanalmira
Post subject: Posted: Tue Jun 13, 2006 10:21 pm

General

Joined: Tue Mar 15, 2005 11:43 pm
Posts: 65
Location: Singapore
Hi krc :

I agree with IR.
Antoher way to control the drain current, you also may want to limit/set your gate biasing voltage, so that it will give you the desired drain current at respective drain voltage. For doing this, you can try to apply voltage divider in the gate bias line.

I hope it helps.

Cheers,
Jean

Posted  11/12/2012

RF Cafe Software

Wireless System Designer

RF & EE Symbols Word
RF Stencils for Visio
Calculator Workbook
RF Workbench
Smith Chartâ„¢ for Visio
Smith Chartâ„¢ for Excel

1996 - 2022
Webmaster:
Kirt Blattenberger,
BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:
AirplanesAndRockets.com

Try Using SEARCH
to Find What You Need.
There are 1,000s of Pages Indexed on RF Cafe !