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RF power transistor datasheet question

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neddie

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Hi to all.
Don't know much about RF so I may be asking a stoopid question. I've attached (I hope) the datasheet
of the BLF571 RF power transistor from NXP. I'm looking at the impedance information on page 4.
It gives the impedances (at 225MHZ). Are these impedances quoted the optimum source and load impedances.
I'm assuming so from the direction of the arrows. If this is the case , can I assume the input impedance
looking into the transistor gate is 9.7-j31.5 and looking back into the drain 31.7-j29.3 , this would make both
impedances capacitive , which is sort of what I'd expect.
This stuff always confuses me :0(
Cheers
Rob
 

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neddie

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Come on , someone must be able to answer this :0)
Or have I broken some forum rule that is stopping poeple from answering?
If . sorry.
 

kspalla

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your assumption is right.
but there is tric here, 9.7-j31.5 need not be impedance of the transistor but understand that you are making the load value to 9.7+j31.5
 

Raza

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Hi,
Yes neddie,
As per datasheet your assumption is right.
 

tyassin

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If this is load-pull data then at least the drain impedance can not be considered to be complex conjugate
 

neddie

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Thanks for the help guys.
It seems that this is a field of electronics that can be difficult to understand if you don't
actually get involved in often :0(
Time for some experimenting :0)
 

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