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RF Power LDMOS Static Characteristics

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memarian

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Dear,

I have a problem with a RF POWER LDMOS:

When i try to test a RF Power LDMOS with a multimeter after about 3 seconds

Drain-Source junction gives me short circuit alarm and Trasistor is dead!(at first

multimeter shows like a diode but it falls down and goes to about zero)

Is there any way to check Static Characteristics of a RF Power LDMOS?

Thanks.
 

springf2000

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use the multimeter is ok,i use the multimeter to check the LDMOS and you should use the static wrist to defeat the ESD!
 

molloy

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You sure the device failed? For instance: if you try to test the Vgs before Vds with the Cgs input you closed the channel of the device and so you could measure a short circuit at the drain side. That doesnt mean the LDMOS failed of course
 

memarian

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Dear,

About Springf2000's answer:

This isn't about ESD.I already used static wrist.when i try to check Drain-Source

Junction (Gate is open) and multimeter is in the diode check position,this happend.

About Molly's answer:

I'm sure.LDMOS failed.I biased the Failed LDMOS :

Vgs=0 V (According to datasheet for ID=20MA @ VDS=10V-->VGSth=3...4V)
I increased VDS from 0 V and @ VDS=1V I get ID=1.5A!!

Thanks alot.
 

PaulHolland

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Hi. What is the maximum Vgs voltage ????... Maybe your multimeter is going over this limit !. I also think you have an ESD problem. I also would not measure the D-S with and open gate!. Not a smart plan.

Paul.
 

memarian

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Dear,

The Vgs(Max) is abot 12V.My multimrter in Diode check position act as 1ma current source and reads the voltage across the p-n junction.This Problem happend only when the multimeter is in diode check position and 2Kohms Position.at other states (measuring larger resistors) there is no problem.i think that current source(1ma) cause the problem.

Thanks.
 

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