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Power FET question - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the 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


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

Site Admin


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:

http://www.radio-electronics.com/info/c ... imiter.php


Good luck!

_________________
Best regards,

- IR


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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







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