Why there is 20mA current in the gate of LDMOS transistor?

[DeeLau]

Hello,

I've a 2.1 GHz LDMOS transistor from freecale, before mounting it on the pc board,
I just use some Alligator clip cables connected between the DC source and the gate/drain pin of the transistor(just transistor, no mounting one the board).

According to the datesheet, the Vds is 28V, and the expected Ids is 250mA, the approx. Vgs is about 3V.

however, when I first turn on the drain voltage, then slowly ajust the gate voltage,
I found even Vgs is already 3V, the Ids is less than 10mA, and when Vgs reach to 3.8V, suddenly the Ids become some hundred mA, and there is also about 20mA current in the gate, is it means the transistor is already osillating? or it's a bad way
just use some Alligator clip cables connected between the DC source and the gate/drain pin of the transistor?

Can someone help me? thanks.

 

[RAJAT AGGARWAAL]

Static is our enemy. It is very bad even my small neighbour's son used to say this.
china parts are also our enemy. my dad say this to all.be away from these enemy of ours
hehe he

 

[FvM]

Apart from what Rajat said, I can hardly imagine to operate a GHz transistor between alligator clips without making a nice oscillator.

So the interesting question is, did you already damage the device or is it just normal operation? I guess, you'll need a more professional test circuit to decide about.

 

[RAJAT AGGARWAAL]

i like to say ,,please dont damage those lovely nice parts...........______
go for circuit for which u buy ur part try it there with a new one
then u get result whatever

 

[biff44]

obviously oscillating